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β-Pinene inhibited germination and early growth involves membrane peroxidation

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Abstract

β-Pinene, an oxygenated monoterpene, is abundantly found in the environment and widely occurring in plants as a constituent of essential oils. We investigated the phytotoxicity of β-pinene against two grassy (Phalaris minor, Echinochloa crus-galli) and one broad-leaved (Cassia occidentalis) weeds in terms of germination and root and shoot growth. β-Pinene (0.02-0.80 mg/ml) inhibited the germination, root length, and shoot length of test weeds in a dose-response manner. The inhibitory effect of β-pinene was greater in grassy weeds and on root growth than on shoot growth. β-Pinene (0.04-0.80 mg/ml) reduced the root length in P. minor, E. crus-galli, and C. occidentalis over that in the control by 58-60, 44-92, and 26-85 %, respectively. In contrast, shoot length was reduced over the control by 45-97 % in P. minor, 48-78 % in E. crus-galli, and 11-75 % in C. occidentalis at similar concentrations. Further, we examined the impact of β-pinene on membrane integrity in P. minor as one of the possible mechanisms of action. Membrane integrity was evaluated in terms of lipid peroxidation, conjugated diene content, electrolyte leakage, and the activity of lipoxygenases (LOX). β-Pinene (≥0.04 mg/ml) enhanced electrolyte leakage by 23-80 %, malondialdehyde content by 15-67 %, hydrogen peroxide content by 9-39 %, and lipoxygenases activity by 38-383 % over that in the control. It indicated membrane peroxidation and loss of membrane integrity that could be the primary target of β-pinene. Even the enhanced (9-62 %) activity of protecting enzymes, peroxidases (POX), was not able to protect the membranes from β-pinene (0.04-0.20 mg/ml)-induced toxicity. In conclusion, our results show that β-pinene inhibits root growth of the tested weed species through disruption of membrane integrity as indicated by enhanced peroxidation, electrolyte leakage, and LOX activity despite the upregulation of POX activity.

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... The increase in cell membrane permeability caused by lipid peroxidation is one of the main mechanisms of antifungal agents (Zhou et al. 2014;Chowhan et al. 2013;Dutta et al. 2012). MDA is one of the major final products of lipid peroxidation, thus it is a vital factor for the evaluation of whether lipid peroxidation increased in the cell membranes (Maness et al. 1999). ...
... The antioxidant enzymes (SOD, CAT, POD) play critical roles in reflecting the level of ROS and the degree of lipid peroxidation (Chowhan et al. 2013). The superoxide radicals first translate into H 2 O 2 and O 2 by SOD, and then, CAT and POD decompose the detrimental ROS H 2 O 2 into the harmless H 2 O and O 2 , followed by regulation of lipid peroxidation (Chowhan et al. 2013, Jaikua et al. 2016. ...
... The antioxidant enzymes (SOD, CAT, POD) play critical roles in reflecting the level of ROS and the degree of lipid peroxidation (Chowhan et al. 2013). The superoxide radicals first translate into H 2 O 2 and O 2 by SOD, and then, CAT and POD decompose the detrimental ROS H 2 O 2 into the harmless H 2 O and O 2 , followed by regulation of lipid peroxidation (Chowhan et al. 2013, Jaikua et al. 2016. The current results showed that the SOD, CAT, and POD activities of MIC-treated samples exhibited the same varying tendency over the entire experimental period. ...
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Matrine is a promising botanical antifungal; however, the mechanism underlying the antifungal activity is yet limited. We studied the antifungal activity of matrine and the underlying mechanism in Botryosphaeria dothidea as a model strain. Matrine strongly inhibited mycelial growth of B. dothidea in a dose-dependent manner. Matrine-treated B. dothidea showed morphological and ultrastructural alterations, including shriveled hyphae, plasmolysis, and leakage of cytoplasm related to cell membrane deterioration. In addition, matrine caused significantly high conductivity and absorbance (260 nm) in extracellular matrices and low lipid contents in B. dothidea, indicating increased membrane permeability. Lipid peroxidation showed that matrine resulted in increased malondialdehyde content while enhancing the generation of reactive oxygen species and the activities of superoxide dismutase, catalase, and peroxidase. These results showed that matrine inhibited the mycelial growth of B. dothidea by enhancing cell membrane permeability via membrane lipid peroxidation.
... They were preferentially partitioned in the membranes, resulting in the increased membrane fluidity and eventually leading to the increase of membrane permeability. In addition, they were reported to induce lipid peroxidation and cause oxidative burst in eukaryotic cells, thereby disturbing the assembly of the membrane, causing changes in fluidity and permeability, resulting in alterations of ion transport and inhibition of metabolic processes (Nigam and Schewe 2000;Singh et al. 2006;Chowhan et al. 2013). In our previous studies, octanal was found to destroy the permeability and integrity of G. citri-aurantii, P. digitatum, and P. italicum hyphae (Scora and Scora 1998;Tao et al. 2014b;Zhou et al. 2014). ...
... Membrane disruption by volatile compounds, as one of the mechanisms for their fungicidal activity, has been suggested (Zhou et al. 2014;Paul et al. 2011). Previous researchers found that volatile compounds could inhibit spores' growth through disruption of membrane integrity and causing peroxidation of lipids due to its lipophilic nature (Chowhan et al. 2013;Singh et al. 2006;Tyagi and Malik 2010). MDA is one of the final products of lipid peroxidation (Halliwell and Gutteridge 2015). ...
... In our study, the addition of octanal significantly increased the extracellular (Fig. 5b) and the total MDA (Fig. 5c) contents of P. digitatum spores, indicating that the lipid peroxidation might exist. LOX is a ubiquitous enzyme in the formation of free radicals and catalyzes the oxidation of membrane lipids (Chowhan et al. 2013). Enhanced LOX activity has been reported to be related to peroxidation of lipids (Maalekuu et al. 2006). ...
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Octanal is a potential alternative to chemical fungicides in controlling postharvest disease of citrus fruit. In this study, the antifungal activity and the underlying mechanism of octanal against spore germination of Penicillium digitatum, one of the main postharvest pathogens in citrus, were investigated. Results showed that octanal at different concentrations (0, 0.25, 0.50, 1.00, 2.00 μl/ml) inhibited the growth of P. digitatum spores in a dose-dependent manner. The morphology and the membrane permeability of P. digitatum spores were visibly altered by 0.25 and 2.00 μl/ml of octanal. Meanwhile, octanal decreased the total lipids contents of P. digitatum spores, indicating that the membrane integrity is damaged. Furthermore, octanal apparently induced the massive accumulation of total malonaldehyde (MDA) and the reactive oxygen species (ROS). An increase in the activities of lipoxygenase (LOX), NADH oxidase, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) was also observed. These results suggested that a membrane damage mechanism involving membrane peroxidation might contribute to the antifungal activity of octanal against P. digitatum spores.
... The observed reduction in CD content paralleled previous studies reporting reduction in CD despite increased MDA Fig. 6 Photomicrographs showing ultrastructure of leaf chloroplast in maize exposed to a control, b β-pinene, c Cr (250 μM) and d Cr (250 μM) + β-pinene. Abbreviations: ch chloroplast, fch flaccid chloroplast, dmth damaged thylakoid Environ Sci Pollut Res formation (Zunino and Zygadlo 2004;Kaur et al. 2011;Chowhan et al. 2013 ). CD are the first index/sign of damage to membranes, whereas MDA is a secondary product that is formed upon reaction with ROS (Halliwell and Gutteridge 1989;Chowhan et al. 2013). ...
... Abbreviations: ch chloroplast, fch flaccid chloroplast, dmth damaged thylakoid Environ Sci Pollut Res formation (Zunino and Zygadlo 2004;Kaur et al. 2011;Chowhan et al. 2013 ). CD are the first index/sign of damage to membranes, whereas MDA is a secondary product that is formed upon reaction with ROS (Halliwell and Gutteridge 1989;Chowhan et al. 2013). A significant amount of Cr was found in plants grown in Cr-fed soil. ...
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Heavy metals’ amassment in the soil environment is a threat to crop and agricultural sustainability and consequentially the global food security. For achieving enhancement of crop productivity in parallel to reducing chromium (Cr) load onto food chain demands continuous investigation and efforts to develop cost-effective strategies for maximizing crop yield and quality. In this context, we investigated the amelioration of Cr(VI) toxicity through β-pinene in experimental dome simulating natural field conditions. The protective role of β-pinene was determined on physiology, morphology and ultrastructure in Zea mays under Cr(VI) stress (250 and 500 μM). Results exhibited a marked reduction in the overall growth (shoot and root length and dry matter) of Z. mays plants subjected to Cr(VI) stress. Photosynthetic pigments (chlorophyll and carotenoids) were evidently reduced, and there was a loss of membrane integrity. Supplementation of β-pinene (100 μM), however, declined the toxicity induced by Cr(VI). Interestingly, Cr-tolerant abilities were improved in relation to plant growth, photosynthetic pigments and membrane integrity with the combined treatment of Cr(VI) and β-pinene. β-Pinene also reduced the root-mediated uptake of Cr(VI) and translocation to shoots. Moreover, significant ultrastructural damages recorded in roots and shoots under Cr(VI) stress were partially reverted upon addition of β-pinene. Our analyses revealed that β-pinene mitigates Cr(VI) toxicity in Z. mays, either by membrane stabilization or serving as a barrier to the uptake of Cr from soil. Thus, exogenous supply of β-pinene can be an effective alternative to mitigate Cr toxicity in soil. However, it is deemed essential to investigate further the responses throughout the life cycle of the plant on β-pinene supplementation under natural conditions.
... It was recently reported that membrane disruption by some antimicrobial compounds correlates with lipid peroxidation (Chowhan et al. 2013;Pasquariello et al. 2015). MDA, an important marker of membrane stress, is the main product of membrane lipid peroxidation (Fadhlaoui and Couture 2016;Zhang et al. 2017). ...
... This was also confirmed by the LOX activity. LOX is a widespread enzyme responsible for the initial stage of membrane lipid peroxidation that catalyses the oxidation of unsaturated fatty acids (Maalekuu et al. 2006;Chowhan et al. 2013). In this study, LOX activity was drastically increased after the addition of GA and was higher than that in the control group, reaching maximum levels at 30 min and then decreasing (Fig. 6d). ...
... The absorbance of the supernatant was measured at 532 nm with a spectrophotometer with correction for non-specific absorbance at 600 and 440 nm. The CD content was determined as described by Chowhan et al. (2013). Briefly, wild-type and transgenic leaf extracts were homogenized in 96 % (v/v) ethanol and centrifuged at 15,000g for 15 min at 4°C. ...
... When the membrane is exposed to free radicals, it is peroxidized and CD is decomposed into toxic aldehydes, such as malondialdehyde (MDA). Monoterpenes, which inhibit growth by peroxidizing lipids, are reported to increase cellular MDA and decrease cellular CD in maize and several weeds (Chowhan et al. 2013;Zunino and Zygadlo 2004). In our study, MDA levels in leaves from 1-month-old Ubi:CaPLA1 Fig. 7 Global expression profiling analysis of commonly regulated genes in three independent Ubi:CaPLA1 lines. ...
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Phospholipids are not only important components of cell membranes, but participate in diverse processes in higher plants. In this study, we generated Capsicum annuum phospholipiase A1 (CaPLA1) overexpressing transgenic rice (Oryza sativa L.) plants under the control of the maize ubiquitin promoter. The T4 CaPLA1-overexpressing rice plants (Ubi:CaPLA1) had a higher root:shoot mass ratio than the wild-type plants in the vegetative stage. Leaf epidermal cells from transgenic plants had more cells than wild-type plants. Genes that code for cyclin and lipid metabolic enzymes were up-regulated in the transgenic lines. When grown under typical paddy field conditions, the transgenic plants produced more tillers, longer panicles and more branches per panicle than the wild-type plants, all of which resulted in greater grain yield. Microarray analysis suggests that gene expressions that are related with cell proliferation, lipid metabolism, and redox state were widely altered in CaPLA1-overexpressing transgenic rice plants. Ubi:CaPLA1 plants had a reduced membrane peroxidation state, as determined by malondialdehyde and conjugated diene levels and higher peroxidase activity than wild-type rice plants. Furthermore, three isoprenoid synthetic genes encoding terpenoid synthase, hydroxysteroid dehydrogenase and 3-hydroxy-3-methyl-glutaryl-CoA reductase were up-regulated in CaPLA1-overexpressing plants. We suggest that constitutive expression of CaPLA1 conferred increased grain yield with enhanced growth in transgenic rice plants by alteration of gene activities related with cell proliferation, lipid metabolism, membrane peroxidation state and isoprenoid biosynthesis.
... Based on several studies, the excessive buildup of reactive oxygen species (ROS), which induces lipid peroxidation, is recognized as an important cause of increased cell membrane permeability [54,55], with H2O2 and MDA levels serving as crucial indicators reflecting the extent of lipid peroxidation in cell membrane [56,57]. In our work, we observed a notable rise in H2O2 and MDA content in F. oxysporum following nerol treatment, indicating that nerol promotes the buildup of ROS within the fungal cells, exacerbating the extent of membrane lipid peroxidation and causing severe disruption to the plasma membrane. ...
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This study explores the in vitro antifungal effects of nerol, a linear acyclic monoterpene alcohol of plant origin, on Fusarium oxysporum, Pestalotiopsis neglecta, and Valsa mali. To further investigate the antifungal mechanism of nerol against F. oxysporum, we examined changes in mycelial morphology and cell membrane integrity-related indices, as well as the activities of antioxidant and pathogenicity-related enzymes. The results demonstrated that nerol exhibited significant concentration-dependent inhibition of mycelial growth in all three fungi, with EC50 values of 0.46 μL/mL for F. oxysporum, 1.81 μL/mL for P. neglecta, and 1.26 μL/mL for V. mali, with the strongest antifungal activity observed against F. oxysporum. Scanning electron microscopy revealed that nerol severely disrupted the mycelial structure of F. oxysporum, causing deformation, swelling, and even rupture. Treatment with 0.04 μL/mL nerol led to significant leakage of soluble proteins and intracellular ions in F. oxysporum, and the Na+/K+-ATPase activity was reduced to 28.02% of the control, indicating enhanced membrane permeability. The elevated levels of hydrogen peroxide and malondialdehyde, along with propidium iodide staining of treated microconidia, further confirmed cell membrane disruption caused by nerol. Additionally, after 12 h of exposure to 0.04 μL/mL nerol, the activity of superoxide dismutase in F. oxysporum decreased to 55.81% of the control, and the activities of catalase and peroxidase were also significantly inhibited. Nerol markedly reduced the activities of pathogenicity-related enzymes, such as endo-1,4-β-D-glucanase, polygalacturonase, and pectin lyase, affecting fungal growth and virulence. In conclusion, nerol disrupts the cell membrane integrity and permeability of F. oxysporum, reduces its virulence, and ultimately inhibits fungal growth, highlighting its potential as an alternative to chemical fungicides for controlling F. oxysporum.
... Shalinder Kaur found that α-pinene from eucalyptus prominently suppressed root length and shoot height of Amaranthus viridis L. at 1.0 µL concentration [43], and another study showed that α-pinene inhibited early root growth and caused oxidative damage in root tissue through increased generation of reactive oxygen species [44]. Some reports have argued that β-pinene inhibited germination and seedling growth of test weeds in a dose-dependent response manner by disrupting membrane integrity [45], altering the plant biochemistry and enhancing the activities of peroxidases and polyphenol oxidases [46]. β-Phellandrene exhibited maximum inhibition to the germination and growth of Vigna unguiculata (L.) Walp at a concentration of 600 ppm [47], whereas, at a concentration of 250 mg/m 3 , camphor suppressed the radicle and shoot growth of Lepidium sativum L. [48]. ...
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Amomum villosum Lour. is a perennial herb of the Zingiberaceae family, which is widely distributed in Xishuangbanna, Yunnan Province in Southwest China. Large amounts of volatile components contained in this plant enter the surrounding atmosphere and soil through volatilization, foliar leaching, root exudation, and residue decomposition. However, the ecological role of these compounds is currently unclear. The aim of this study was to compare the differences in the composition of volatile oils from stems, leaves, and young fruits of A. villosum, identify chemicals that had allelopathic effects, and explore the effects of the oil on the diversity and composition of soil microbiomes. Volatile oils were obtained by steam distillation and characterized by gas chromatography–mass spectrometry, and then were tested for allelopathic activity using seedlings of Lactuca sativa L. and Lolium perenne L. as test species. The results showed that the oils from stems and leaves were rich in monoterpene hydrocarbons, unlike the oxygenated monoterpenes which dominated oils from young fruits. Leaves > stems > young fruits: this was the order of the allelopathic effects of volatile oils from various A. villosum organs. Among the four main chemical components in the oils, only α-pinene, which is abundant in leaves, had a stronger allelopathic action than the crude oils, implying that it might be a potential allelochemical. Experiments on soil microorganisms indicated that 3.0 mg/mL oil had the greatest effect on the structure of the soil fungal community. It can be concluded that A. villosum is capable of releasing allelochemicals which affect the growth of other plant species and the diversity and community structure of soil microorganisms.
... The essential oil in the inflorescences of S. canadensis showed antimicrobial activity, antioxidant activity and free-radical scavenging activity, and its main components were α-pinene, germacrene D and limonene [87]. α-Pinene and β-pinene were reported to disturb the cell division through the interference of DNA synthesis, and cause membrane peroxidation [93][94][95]. Several monoterpenes were reported to alter soil microflora [96]. ...
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Solidago canadensis L. and Solidago altissima L. are native to North America and have naturalized many other continents including Europa and Asia. Their species is an aggressive colonizer and forms thick monospecific stands. The evidence of the allelopathy for S. canadensis and S. altissima has accumulated in the literature since the late 20th century. The root exudates, extracts, essential oil and rhizosphere soil of S. canadensis suppressed the germination, growth and the arbuscular mycorrhizal colonization of several plants, including native plant species. Allelochemicals such as fatty acids, terpenes, flavonoids, polyphenols and their related compounds were identified in the extracts and essential oil of S. canadensis. The concentrations of total phenolics, total flavonoids and total saponins in the rhizosphere soil of S. canadensis obtained from the invasive ranges were greater than those from the native ranges. Allelochemicals such as terpenes, flavonoids, polyacetylene and phenols were also identified in the extracts, essential oil and the rhizosphere soil in S. altissima. Among the identified allelochemicals of S. altissima, the cis-dehydromatricaria ester may be involved in the allelopathy considering its growth inhibitory activity and its concentration in the rhizosphere soil. Therefore, the allelopathy of S. canadensis and S. altissima may support their invasiveness, naturalization and formation of thick monospecific stands. This is the first review article focusing on the allelopathy of both of S. canadensis and S. altissima.
... For an instant, phytotoxins found in Artemisia species are known to be or can be converted into germination-inhibitory chemicals (Wei et al. 2020). Moreover, various components such as chlorogenic acid, luteolin, gallic acid, p-coumaric, β-pinene, and γ-curcumene identified in A. capillaris (Jung et al. 2012;Nigam et al. 2019;Vokou et al. 2003;Won 2009), several flavonoids (quercetin, epicatechin, and rutin) isolated from L. davurica (Xu et al. 2010) are known to have inhibitive effects on membrane permeability, mitochondrial respiration, protein synthesis, and enzymatic activities and therefore, might be responsible for delaying the seed germination (Chowhan et al. 2013;Ertani et al. 2016;Fig extracts reaches a certain level (Kato-Noguchi et al. 2017). Therefore, we conclude that the difference in the inhibition effects might be related to the tolerance mechanism of plants, and hence, alfalfa was more sensitive to the applied extracts compared to wheat. ...
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Previous pasture residues can inhibit the establishment of exotic introduced plant species by exerting allelopathic effects. Concerning this issue, present research work was conducted to investigate the allelopathic potential of dominant native grass species (Lespedeza davurica, Stipa bungeana, and Artemisia capillaris) on the seed germination and seedling growth of exotic plant species (alfalfa and wheat). Different concentrations (2.5%, 5%, and 10%) of residue extracts of native grass species were used in the experiment. Results indicated that the aqueous extracts of A. capillaris and S. bungeana at all concentrations significantly suppressed the seed imbibition, germination potential, germination rate, germination index, seedling height, above and belowground biomass of alfalfa seedlings. Meanwhile, L. davurica did not show any effect on germination indexes but it significantly suppressed the seedling height of alfalfa after two weeks. However, it improved the seed imbibition, seedling height, and biomass of wheat seedlings. The greatest inhibition effect was perceived by A. capillaris followed by S. bungeana extracts. To achieve sustainable agricultural development, it is important to utilize cultivation systems that take advantage of the stimulatory and inhibitory effects of allopathic plants to regulate plant growth and development and to minimize the risk of toxicity caused by allopathic plants species. Graphical Abstract Overall processes of allelopathy and how allelochemicals are derived from the aerial parts of plants and reveals that allelochemical compounds primarily contain phenolic compounds, terpenes, and fatty acids, which influence the seed germination, survival, growth, and development of other plants (e.g., crops or weeds).
... The monoterpenoid eucarvone (2,6,6-trimethy-2,4-cycloheptadien-1one) was also previously shown to induce O 2 − overproduction at 158 µmol/L in susceptible finger millet roots (Sunohara et al., 2015). In addition, other monoterpenoids, including β-myrcene (7-methyl-3-methylene-1,6-octadiene) (Singh et al., 2009), α-pinene (Singh et al., 2006), β-pinene (Chowhan et al., 2013), and safranal (2,6,6-trimethyl-1, 3-cyclohexadiene-1-carboxaldehyde) (Mardani et al., 2019), were also reported to increase generation of H 2 O 2 , a different type of ROS, and oxidative injury in sensitive plant species. In addition, increase of oxidative stress after treatment of other monoterpenoids such as camphor (1,7, 7-trimethylbicyclo[2.2.1]heptan-2-one), 1,8-cineole (1,3,3-trimethyl-2-oxabicyclo[2.2.2]octane), geraniol ((trans)− 3,7-dimethyl-2,6-octadien-1-ol), menthol (5-methyl-2-(propan-2-yl)-cyclohexan-1-ol), and thymol (2-isopropyl-5-methylphenol) have been reported in sensitive maize (Zunino and Zygadlo, 2004). ...
Article
Phytogrowth-inhibitory activities of volatile compounds produced by cumin seeds (Cuminum cyminum L.) and phytotoxic effects induced by the compound with strong phytotoxic activity were investigated as a first step to elucidate the mode of action of the compounds. By gas chromatography-mass spectrometry (GC–MS) analyses, α-pinene (2,6,6-trimethylbicyclo[3.1.1]hept‑2-ene)), β-pinene (6,6-dimethyl-2-methylenebicyclo[3.1.1]heptane), cuminaldehyde (4-(1-methylethyl)benzaldehyde), and p-cymene (1-methyl-4-(1-methylethyl) benzene) were identified as volatile compounds from the cumin seeds. Among them, cuminaldehyde showed the highest phytotoxic activity in lettuce seedlings. The compound also exhibited broad-spectrum growth inhibitory activity against dicot and monocot species; however, maize, wheat, common bean, and Indian jointvetch were relatively tolerant to it. In roots of onion, a sensitive species to cuminaldehyde, the compound induced a decrease in the viability and population of mitotic cells and an increase in reactive oxygen species (ROS) production, programmed cell death (PCD), and loss of membrane integrity, in a concentration-dependent manner. Cuminaldehyde-induced growth inhibition in onion roots may be due to ROS overproduction, which may induce oxidative DNA damage, cell cycle arrest, and loss of membrane integrity, resulting in cell death including PCD and necrosis.
... The β-pinene was reported to have antifungal and antibacterial properties [48]. In addition, it inhibits weed growth through the disruption of membrane integrity as indicated by enhanced peroxidation, electrolyte leakage, and lipoxygenase activity despite the upregulation of peroxidase [49]. For the essential oil of A. xanthioides stems, 28 compounds were identified as representing 98.39% of the total essential oil content (Table 1). ...
Article
The essential oil from leaves, roots, stems, and fruits of Amomum xanthioides Wall. ex Baker from Northern Vietnam was obtained by hydrodistillation and analyzed by gas chromatography techniques. The yield of the essential oil obtained from leaves, roots, stems, and fruits of A. xanthioides was 0.26%, 0.24%, 0.19%, and 1.45% (w/w) by fresh weight, respectively. The composition of the oil samples was compared; 38, 43, 28, and 22 compounds have been identified in the essential oil of leaves, roots, stems, and fruits, accounting for 96.19%, 96.61%, 98.39%, and 98.12% of the total oil content, respectively. A high variation among organs for the majority of compounds was shown. β-elemene (31.71%), δ-cadinene (10.69%), germacrene D (9.55%), bicycloelemene (8.12%), and bicyclogermacrene (7.93%) are the main compounds in leaves, while β-pinene (29.59%), terpinen-4-ol (10.77%), and α-terpinene (6.96%) are identified as the main compounds in roots. Stems are characterized by high levels of β-elemene (29.58%), spathoulenol (26.89%), and bicycloelemene (6.19%). For fruits, bornyl acetate (37.21%), camphor (19.48%), camphene (14.62%), and limonene (9.64%) are the main compounds. Overall, this study confirms that changes in the yield, composition, and concentration of the essential oil may be caused by several factors such as environmental conditions and climate at the collection site, the time of collection, and the age and properties of plants. This study also provides new data on the chemical composition of the essential oil from A. xanthioides collected from Northern Vietnam.
... In a similar experiment determining germination and growth inhibition by β-pinene EL, lipid peroxidation and lipoxygenase (LOX) activity were assessed. The result showed a strong increase in EL, dienes and H 2 O 2 content and the authors suggest that despite an increase in the activity of ROS scavenging enzymes, root membrane integrity was lost [42]. Later on, they studied the early ROS generation and activity of the antioxidant defense system in the root and shoot of hydroponic wheat. ...
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The extensive use of chemical pesticides leads to risks for both the environment and human health due to the toxicity and poor biodegradability that they may present. Farmers therefore need alternative agricultural practices including the use of natural molecules to achieve more sustainable production methods to meet consumer and societal expectations. Numerous studies have reported the potential of essential oils as biopesticides for integrated weed or pest management. However, their phytotoxic properties have long been a major drawback for their potential applicability (apart from herbicidal application). Therefore, deciphering the mode of action of essential oils exogenously applied in regards to their potential phytotoxicity will help in the development of biopesticides for sustainable agriculture. Nowadays, plant physiologists are attempting to understand the mechanisms underlying their phytotoxicity at both cellular and molecular levels using transcriptomic and metabolomic tools. This review systematically discusses the functional and cellular impacts of essential oils applied in the agronomic context. Putative molecular targets and resulting physiological disturbances are described. New opportunities regarding the development of biopesticides are discussed including biostimulation and defense elicitation or priming properties of essential oils.
... They also enhanced transpiration by interfering with the cuticular waxes and damaging stomata (Schulz et al. 2007) and caused various physiological alterations (Dudai et al. 2000). EOs/components also induced oxidative stress in test plant via generating the ROS (Kaur et al. 2011;Chowhan et al. 2013;Ahuja et al. 2015) and altering the plant water balance (Graña et al. 2016;Araniti et al. 2017a). Despite numerous reports on the phytotoxicity of essential oils and their constituents, their primary target point still remains unclear. ...
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The present study was conducted to evaluate the phytotoxic potential of Pogostemon oil in terms of oxidative stress on two weeds, viz. Avena fatua L. and Phalaris minor Retz. GC–MS analysis revealed that Pogostemon oil is rich in sesquiterpenes with azulen-2-ol, 1,4-dimethyl-7-(1-methyl ethyl)-as the major component of the oil with maximum % area (28.2%). For the laboratory bioassay, oil emulsion of different concentrations, ranging from 0.25 to 2.5 mg mL−1, was prepared. The effect of oil treatment was studied on per cent germination, seedling length, chlorophyll content and dry weight of the test plants. The inhibitory effect of Pogostemon oil was much pronounced on Avena fatua as compared to Phalaris minor. Roots were adversely affected due to oxidative damage. Consequently, oxidative damage, IC30, IC50 and IC70 values for A. fatua were calculated. Pogostemon oil treatment induced excessive generation of ROS leading to oxidative stress in test plant. ROS further disintegrated membrane integrity as evident from the increased level of MDA, REL and decreased level of CDs. Further exposure to Pogostemon oil enhanced the activities of antioxidant enzymes, thus indicating the activation of ROS scavenging mechanism. Thus, Pogostemon oil inhibits the growth of test plant via inducing oxidative stress and therefore shows potential towards weed management.
... This could be related to the different EOs and terpenes tested in those investigations, as they could be significantly determining for the effect as reported in the present study. The membrane peroxidation results can also comply with previous studies, as EOs were reported to cause peroxidation of polyunsaturated fatty acids in the weeds' bio membranes [52,53]. However, differently from our findings, the detected membrane peroxidation was in many cases correlated to the EL [54]. ...
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The current study aimed to assess the allelopathic effect of Rosmarinus officinalis L. essential oils (EOs) to define the potent effect against weed species, by exploring distinct chemotypes and their main compounds. The EOs from eight accessions were characterized. Their components were identified by gas chromatography, and four chemotypes were defined; C1 (α-pinene), C2 (camphor), C3 (α-pinene/1,8-cineole), and C4 (α-pinene/1,8-cineole/camphor). Four concentrations of the EOs (400, 800, 1200, and 2400 μL/L) and the main compounds of each chemotype were tested in a laboratory assay against Amaranthus retroflexus L. and Lolium perenne L. in pre-and post-germination. The results showed that the EOs significantly affected all the tested parameters (germination, early growth, and physiological and histological parameters of the weeds under study) in a dose, chemotype, and species dependent manner. A. retroflexus was more sensitive than L. perenne at germination level being significantly inhibited at the lowest dose of all the chemotypes. The latter all exhibited significant effects but with a higher potency of C2 (camphor chemotype) and C3 (-pinene/1,8-cineole chemotype), as well qualitative differences in the induced damage. Our results thus increase knowledge about the role of the monoterpene composition in bio-herbicidal effect, which can help in the development of EO based bio-herbicides.
... SOD, CAT and POD are important antioxidant enzymes which are able to scavenge ROS and thus play a critical role in reducing the degree of membrane lipid peroxidation (Chowhan et al., 2013). Several reports said that the reduction of antioxidant enzyme activity could cause a rapid accumulation of ROS, followed by membrane lipid peroxidation Kumari et al., 2017). ...
... However, other studies demonstrated that α-pinene exhibited a certain inhibition of the early root growth of other weeds such as Cassia occidentalis (L.) Link., as well as oxidative damage in root tissue [10]. Similarly, the compound β-pinene was shown to be responsible for the disruption of membrane integrity, the enhancement of peroxidation and electrolyte leakage in Phalaris minor and particularly in E. crus-galli [68]. ...
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Background: essential oils are well known for their pharmacological effectiveness as well as their repellent, insecticide, and herbicide activities. The emergence of resistant weeds, due to the overuse of synthetic herbicides, makes it necessary to find natural alternatives for weed control. The aim of this study was to evaluate the phytotoxic effects of Eucalyptus citriodora, Lavandulaangustifolia, and Pinus sylvestris, three common commercial essential oils, on weeds (Portulaca oleracea, Lolium multiflorum, and Echinochloa crus-galli), food crops (tomato and cucumber), and the invasive species Nicotiana glauca. Methods: to determine herbicidal effects, essential oils were tested at different concentrations (0.125-1µL/mL). The index of germination and seedling length data were recorded over 14 days. Results: the in vitro assays showed that L. angustifolia with linalool (38.7 ± 0.1%), 1,8-cineole (26.5 ± 0.1%), and camphor (14.2 ± 0.1%) as the main compounds showed the most phytotoxic effects affecting seed germination in weeds and tomato, and the aforementioned invasive species. L. multiflorum was the most sensitive weed, particularly to lavender essential oil, which decreased the growth of its hypocotyl and radicle by 87.8% and 76.7%, respectively, at a dose of 1 µL/mL. Cucumber was the most resistant food crop, with no significant reduction observed in seed germination and hypocotyl growth with E. citriodora and L. angustifolia essential oils. Conclusions: lavender essential oil represents a promising candidate for the development of effective and safe herbicides in the management of L. multiflorum affecting cucumber crops.
... The antioxidant behavior of isoprenes and monoterpenes has been attributed to the presence of conjugated double bond that may arbitrate electron and energy transfer, enabling them to scavenge free radicals (Vickers et al. 2009). Monoterpenes being lipophilic can permeate through cell membrane (Chowhan et al. 2013;Pham et al. 2015) and manipulate defense genes and certain transcription factors in plants (Godard et al. 2008). Monoterpenes act as signaling molecules and trigger a signal similar to a mild stress, and thereby may incite the expression of certain stress-linked genes (Lee and Seo 2014). ...
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We examined the possible role of monoterpene β-pinene in providing protection against Cr(VI) toxicity in maize (Zea mays). Treatment with β-pinene (10 μM) significantly alleviated Cr(VI) accumulation and recuperated Cr(VI) caused decline in root and coleoptile growth in maize. β-Pinene addition caused a decline in Cr(VI)-induced accumulation of superoxide anion, hydroxyl ion, hydrogen peroxide and confirmed by in-situ detection of ROS using histochemical localization. It suggested that the β-pinene quenches/neutralizes enhanced ROS generated under Cr(VI) exposure. β-Pinene also reduced Cr(VI)-induced electrolyte leakage, thereby suggesting its role in membrane stabilization. Further, β-pinene regulated the activity of scavenging enzymes, thereby suggesting a role in modulating Cr(VI)-induced oxidative damage. In conclusion, our results suggest that the addition of β-pinene has a protective role against Cr(VI) stress and provides resistance to maize against Cr(VI) toxicity.
... Importantly, we found that the levels of POD and CAT in the PC are significantly higher than in the NC (Figures 7D,E). MDA is a product of unsaturated lipid peroxidation in biofilms (Ciniglia et al., 2015) and, as a result, its quantity can directly reflect the degree of membrane lipid peroxidation (Draper and Hadley, 1990) and the amount of its accumulation determines the degree of damage to plants (Chowhan et al., 2013). In this light, we observed that after F. oxysporum infection the amount of MDA in the PC is significantly higher than in the NC (Figure 7B). ...
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The root of Panax notoginseng (P. notoginseng) is one of the most highly valuable medicinal herbs in China owing to its pronounced hemostatic and restorative properties. Despite this important fact, growing P. notoginseng is seriously limited by root-rot diseases. In studies aimed at developing a solution to this problem, environment-friendly essential oils (EOs) of five medicinal plants of the family Zingiberaceae were tested for their inhibitory effects on the growth of three main soil pathogens associated with the root-rot diseases of P. notoginseng. The results showed that the EOs of Alpinia katsumadai Hayata and Zingiber officinale Roscoe promote significant reductions in the mycelium growth of the pathogen in vitro at a concentration of 50 mg mL⁻¹, which is much higher than that needed (5 mg mL⁻¹) to reduce growth by the positive control, flutriafol. Furthermore, the chemical components of the two EOs were determined by using GC-MS analysis. Eucalyptol was found to account for more than 30% of the oils of the two plants, with the second major components being geranyl acetate and α-terpineol. These substances display different degrees of fungistasis in vitro. To further determine the effects of the EO of Zingiber officinale (Z. officinale) in vivo, soilless cultivation of P. notoginseng with pathogen inoculation was conducted in a greenhouse. Addition of the petroleum ether extract (approximately equal to EO) of Z. officinale to the culture matrix causes a large decrease in both the occurrence and severity of the P. notoginseng root-rot disease. The decreasing trend of net photosynthetic rate (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr) were all alleviated. In addition, the activities of catalase (CAT), peroxidase (POD), and the malondialdehyde (MDA) content were also largely reduced after pathogen infection, with the root activity being higher than that of the control. Taken together, the findings reveal that the EOs from plants might serve as promising sources of eco-friendly natural pesticides with less chemical resistance.
... Interestingly, β-pinene was found in all the tissues, except seeds. Pinene is a naturally occurring constituent of the essential oils in many plant species that has a relevant role in insect repellency and allelopathy (inhibiting root growth of the tested weed species) (Bohlmann et al., 1997;Phillips et al., 1999;McKay et al., 2003;Hassanpouraghdam, 2011;Chowhan et al., 2013;Huang et al., 2013;Pajaro-Castro et al., 2017). AvPS (AvTPS1) catalyzed GPP to form α-pinene and β-pinene, producing 63% β-pinene as a major product. ...
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Amomum villosum, also known as Fructus Amomi, has been used to treat digestive diseases such as abdominal pain, vomiting, and dysentery. Volatile terpenoids are the active metabolites in the essential oil of Fructus Amomi. Nevertheless, downstream genes responsible for activating metabolites biosynthesis in A. villosum still remain unclear. Here, we report the use of an integrative volatile terpenoid profiling and transcriptomics analysis for mining the corresponding genes involved in volatile terpenoid biosynthesis. Ten terpene synthase (TPS) genes were discovered, and two of them were cloned and functionally characterized. AvTPS1 (AvPS: pinene synthase) catalyzed GPP to form α-pinene and β-pinene; AvTPS3 (AvBPPS: bornyl diphosphate synthase) produced bornyl diphosphate as major product and the other three monoterpenoids as minor products. Metabolite accumulation and gene expression pattern combined with AvPS biochemical characterization suggested that AvPS might play a role in biotic defense. On the other hand, the most active ingredient, bornyl acetate, was highly accumulated in seeds and was consistent with the high expression of AvBPPS, which further indicated that AvBPPS is responsible for the biosynthesis of bornyl acetate, the final metabolite of bornyl diphosphate in A. villosum. This study can be used to improve the quality of A. villosum through metabolic engineering, and for the sustainable production of bornyl acetate in heterologous hosts.
... The herbicide action of 27 monoterpenes on Raphanus sativus and Lepidium sativum was studied by De Martino et al., (2010), who found that these compounds cause inhibition of germination and growth of plants and may thus be used in the development of new herbicides. In another study, Chowhan et al., (2013) found inhibitory effect on germination and growth of roots and shoots of Phalaris minor, Echinochloa crus-galli and Cassia occidentalis by the action of the oxygenated β-pinene monoterpene, which showed that this compound acts on the integrity of cells plasma membrane. Also, Barton et al., (2010) found that 1.8 cineol, major compound of eucalyptus essential oil, caused herbicidal effect on Lolium rigidum and Raphanus sativus. ...
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The large production of poultry is in part due to antimicrobials that are used to improve broiler chicken performance, although in recent years this practice has been questioned due to suspected appearance of residues in the meat and resistant microorganisms. Thus, the essential oils emerge as promising substitutes to the usual growth promoters. The aim of this study was to analyze the state of the art concerning the use of essential oils as additives in broiler diets and such data will be used to conduct further studies in the future. The databases used were SciELO, Portal Capes, Science Direct and PubMed. 42 papers published between 2005 and 2014 were selected. 27 plant species were tested, and oregano was the most used. The essential oils act in different ways in the organism of the animals, going beyond the antimicrobial activity and showing effect on several productive parameters of the poultry, with results similar or better than those of antimicrobials.
... Indeeed, β-Pinene (at concentrations ≥ 0.04 mg mL -1 ) significantly reduced the root and coleoptile length of rice, total chlorophyll content, enhanced the accumulation of macromolecules (proteins and carbohydrates) and inhibited the activities of hydrolyzing enzymes such as proteases, α-amylases, and β-amylases (Chowhan et al., 2011). Recently, Chowhan et al. (2013) observed, in weeds (E. crusgalli, Phalaris minor and Cassia occidentalis) treated with the same molecule, lipid peroxidation and loss of membrane integrity concluding that membrane could be the primary target of β-Pinene. ...
Article
Foliar volatiles and essential oils produced by apple mint [Mentha rotundifolia auct. non (L.) Huds.], a widely distributed Mediterranean species, were investigated for their phytotoxic activities on seed germination and/or root growth of the sensitive test species Lactuca sativa and four of the most common weeds largely found in several agro-ecosystems (Amaranthus retroflexus, Chenopodium album, Echinochloa crusgalli and Eleusine indica). The results pointed out that foliar volatiles (VOCs) were characterized by a high inhibitory effect on both germination and root growth of lettuce. Moreover, apple mint essential oils, extracted from fresh material through steam distillation, were characterized by a high phytotoxicity on weeds germination and root growth. The chemical characterization of the essential oils, carried out through GC-MS, highlighted that monoterpenes were the main chemicals followed by sesquiterpenes. Interestingly, the most abundant compounds were α-pinene, β-pinene and limonene, which are largely known to be strong phytotoxic allelochemicals.
... β-pinene was more potent against T. castaneum than linalool. This compound is an oxygenated monoterpene which is abundantly present in the environment, and is widely found in plants as a constituent of EOs [14]. It has been reported with acute toxicity to insects of T. castaneum after three days of exposure [15]. ...
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Effective, ethical pest control requires the use of chemicals that are highly specific, safe, and ecofriendly. Linalool and β-pinene occur naturally as major constituents of the essential oils of many plant species distributed throughout the world, and thus meet these requirements. These monoterpenes were tested as repellents against Tribolium castaneum, using the area preference method, after four hours of exposure and the effect transcriptional of genes associated with neurotransmission. Changes in gene expression of acetylcholinesterase (Ace1), GABA-gated anion channel splice variant 3a6a (Rdl), GABA-gated ion channel (Grd), glutamate-gated chloride channel (Glucl), and histamine-gated chloride channel 2 (Hiscl2) were assessed and the interaction with proteins important for the insect using in silico methods was also studied. For linalool and β-pinene, the repellent concentration 50 (RC50) values were 0.11 µL/cm2 and 0.03 µL/cm2, respectively. Both compounds induced overexpression of Hiscl2 gen in adult insects, and β-pinene also promoted the overexpression of Grd and the Ace1 gene. However, β-pinene and linalool had little potential to dock on computer-generated models for GABA-gated ion channel LCCH3, nicotinic acetylcholine receptor subunits alpha1 and alpha2, and putative octopamine/tyramine receptor proteins from T. castaneum as their respective binding affinities were marginal, and therefore the repellent action probably involved mechanisms other than direct interaction with these targets. Results indicated that β-pinene was more potent than linalool in inducing insect repellency, and also had a greater capacity to generate changes in the expression of genes involved in neuronal transmission.
... The observation made in the present study is in parallel to previous reports where volatile allelochemicals were found to decrease the chlorophyll content in the plants and consequently interferes with the photosynthetic activity of the plants (Batish et al., 2004;Kaur et al., 2010;Araniti et al., 2017). Although the exact cause of decrease in the total chlorophyll content is not known, it could be either due to inhibition of chlorophyll synthesis or enhanced chlorophyll degradation or both (Yang et al., 2004;Chowhan et al., 2013). ...
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The work was undertaken to investigate the phytotoxic potential of essential oil from Melaleuca leucadendra against three weed species, viz., Echinochloa crus-galli, Cyperus rotundus and Leptochloa chinensis. It was observed that volatile oil (0.25-1.5 mg ml-1) of Melaleuca retarded the germination and growth of all the test weeds in a dose-response bioassay conducted under laboratory conditions. Generally, both root and shoot length showed an inhibitory effect in a concentration dependent manner and the maximum effect was observed in C. rotundus, followed by E. crus-galli and L. chinensis. The Melaleuca oil not only affected the germination and seedling growth of the test weeds, but also inhibited the chlorophyll content and dry weight. At the highest dose of Melaleuca oil treatment (1.5 mg ml-1), the chlorophyll content declined by nearly 50% in E. crus-galli and 90% in L. chinensis over the control. Thus, it is concluded that volatile oil possesses phytotoxic potential towards other plants and could be further explored for weed management.
... ambrosioides respectively (Fig 4). This fact is also supported by some earlier studies demonstrating an increase in cellular respiration in response to monoterpenes, possibly to meet the increased demand of energy by the plant [27]. ...
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Present study was conducted to explore the herbicidal effect of volatile essential oil of Mentha longifolia (L.) L. and Chenopodium ambrosioides L. against Avena fatua L. weed. A significant effect of essential oil was observed on early seedling growth, chlorophyll content and cellular respiration over a concentration range of 0.01 – 0.25 mg/ml as compared to control ones. More inhibition was observed in shoot length as compared to root length. Greater Inhibitory effect was observed in M. longifolia oil followed by C. ambrosioides oil. The Essential oil of both the plants caused loss in chlorophyll content and also causes impairment in cellular respiration, thus, affecting the overall physiological growth of test weed. The study concludes that these essential oils has bio-herbicidal property and can be used as environmentally safe bioherbicide.
... The relative electrolyte leakage (REL) assay. REL analysis was conducted in imbibed seeds with both non-freezing treatments and cooled to − 5, − 10, − 15 and − 20 °C at fast and slower rates using a method described by Chowhan et al. 54 . Briefly, 0.5 g seeds were added into the 50 ml-tubes with 5 mL deionized water, Scientific RepoRts | 7:44166 | DOI: 10.1038/srep44166 then mixed thoroughly by placing the tubes in a shaker (Kylin-Bell Lab Instruments Co. Ltd., Jiangsu, China) for 2 h before measuring the electrolyte leakage (EL) using a conductivity meter (Cold-Parmer, USA). ...
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The physiological mechanisms by which imbibed seeds survive freezing temperatures in their natural environment have been categorized as freezing avoidance by supercooling and freezing tolerance by extracellular freeze-desiccation, but the biochemical and molecular mechanisms conferring seed freezing tolerance is unexplored. In this study, using imbibed Lactuca sativa seeds we show that fast cooled seeds (60 °C h−1) suffered significantly higher membrane damage at temperature between −20 °C and −10 °C than slow cooled (3 °Ch−1) seeds (P < 0.05), presumably explaining viability loss during fast cooling when temperature approaches −20 °C. Total soluble sugars increase in low temperature environment, but did not differ significantly between two cooling rates (P > 0.05). However, both SOD activity and accumulation of free proline were induced significantly after slow cooling to −20 °C compared with fast cooling. RNA-seq demonstrated that multiple pathways were differentially regulated between slow and fast cooling. Real-time verification of some differentially expressed genes (DEGs) revealed that fast cooling caused mRNA level changes of plant hormone and ubiquitionation pathways at higher sub-zero temperature, whilst slow cooling caused mRNA level change of those pathways at lower sub-zero ttemperatures. Thus, we conclude that imbibed seed tolerate low temperature not only by physiological mechanisms but also by biochemical and molecular changes.
... Several reports have shown that monoterpenes, among them camphor, cineol, aand b-pinenes, either individually or in combination, inhibit the germination of seeds of several species (Weidenhamer et al. 1993;Angelini et al. 2003;Vokou et al. 2003). It has been shown that aand b-pinenes induce a diversity of physiological effects on seeds and seedlings: (a) inhibition of seed germination and seedling growth (Kordali et al. 2007); (b) inhibition of radicular growth (Nishida et al. 2005); (c) degradation of chloroplast membranes and blockage of the photosynthesis electron flow (Klinger et al. 1991); (d) changes in the composition of fatty acids and membrane lipid peroxidation (Zunino and Zygadlo 2004); (e) stimulus or inhibition of the respiratory rate (Abrahim et al. 2000(Abrahim et al. , 2003; (f) inhibition of the electron flow in mitochondria, causing a rise in the production of reactive oxygen species (ROS) and consequent lipid peroxidation (Ishii-Iwamoto et al. 2012;Chowhan et al. 2013); (g) effects on abscisic acid, ethylene and gibberellins (Koornneef et al. 2002;Nambara and Marion-Poll 2003); (h) anatomical alterations in radicle structure (Abrahim et al. 2000). To our knowledge, the present paper is the first report about effects of pinenes on the elongation of cell seedlings. ...
Article
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Propolis is a complex mixture of beeswax, resinous and volatile substances produced by honeybees with material collected from plant exudates. The essential oil obtained from a propolis samples from southern Brazil was extracted by hydro-distillation. The yield of oil is high (8.5%), and its major constituents are the monoterpenes α-pinene (86%), β-pinene (12%) and camphene (1%). At 1% concentration, the oil inhibited the germination of lettuce seeds. At 0.25%, the growth speed index and the growth of the hypocotyl–radicle axis reduced substantially. The oil at 0.5% inhibited the elongation of procambial cells and shifted the elongation of the ground meristem cells axially to radially. Hence, the elongation zone assumed a stratified arrangement. In radicles from seeds treated with oil at 1%, a radially directed cell elongation took place in the root cap, protoderm and procambium, preventing the root to protrude. Intercellular spaces appeared between layers of cells of the ground meristem. The anatomical changes observed might be an effect of monoterpenes, either promoting the production of ethylene or affecting the sensitivity of meristem cells to this regulator.
... In this context, Batish et al. and Vasilakoglou et al. 7,71 have demonstrated that monoterpenes strongly inhibit seed germination and reduce plant growth. Indeed, βpinene has been found to inhibit germination, reduce plant growth and induce various biochemical alterations, including loss of plasma membrane integrity 12 and impairment of protein and carbohydrate metabolism 11 . ...
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The present study aims to evaluate the Cupressus sempervirens leaves phytotoxicity. Their leachate (100, 200, 300, 400 and 500 g/l), aqueous (10, 20, 30 and 40 g/l) and organic (petroleum ether, chloroform and acetone, at 2000, 4000 and 6000 ppm) extracts were tested on radish, lettuce, barley and tomato. Pot cultures were conducted by incorporation of leaves powder (50 and 100 g/kg) in soil and by irrigation with leaves leachate and aqueous extracts at IC50 and MIC, concentrations causing, respectively 50% and 100% inhibition. Over all, rate germination did not affected, however germination speed was significantly delayed. For growth, aqueous extracts had the most significant toxicity at 40 g/l and leachate at 500 g/l, inducing up to a total inhibition. The strongest toxicity of organic extracts, was recorded at 6000 ppm (30 mg) for the three ones. Radish seedling growth was more sensitive, especially to petroleum ether and acetone fractions whereas tomato showed a great sensitivity especially to petroleum ether fraction. Residues incorporation in soil (at 100 g/kg) significantly decreased root (86–99%) and shoot (65–100%) length of target species. Irrigation with aqueous extracts and leachate was harmful for especially, tomato and lettuce. Quantitative and qualitative analysis of the extracts were carried out by gas chromatography-mass spectrometry (GC-MS). Results showed that C. sempervirens had a significant allelopathic potential. This plant may be favorably used for incorporating in agricultural systems for sustainable weed management.
... Nishida et al. (46) demonstrated that monoterpenes [Eucalyptol, α-pinene, camphor and camphene] inhibited the mitosis through interference with DNA synthesis in meristematic cells. Chowhan et al. (28,29) reported that monoterpenes [α -pinene, camphor, camphene (46) and citronellal (52)] inhibited the cell division in growing root tips and β-pinene inhibited the germination and early growth due to membrane peroxidation. Barney et al. (9), reported that as in our case, none of the individual monoterpenes caused observed phytotoxicity, but it was a synergistic effect of many monoterpes. ...
Article
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This study aimed to identify the main components of essential oil (EO) produced by S. canadensis and S. gigantea and evaluate their phytotoxicity on radish (Raphanus sativa L.), and garden cress (Lepidium sativum). Plant samples were collected from 5-localities in east Slovakia (Šalgovík, Rúrky, Ľubotice, Solivar and V. Šebastová). The chemical compositions of EO were determined by GC-MS. Number of identified components in EO ranged from 39 to 52 for S. canadensis and 58 for S. gigantea. The major components differed between the 5-sampling sites.-elemene were main components (over 5% each) identified in S. Canadensis. While curlone, tumerone and δ-cadinene were identified as dominant components in S. gigantea. Two samples from Rúrky and Ľubotice were stimulatory and one sample from Solivar was inhibitory to seed germination of radish. Samples from Rúrky and V. Šebastová significantly inhibited the seed germination of garden cress. Application of EO from Rúrky and V. Šebastová on radish and EO from Ľubotice and V. Šebastová on garden cress significantly stimulated the radicle elongation. However, the EO from Solivar inhibited the radical elongation of garden cress.
... In fact, the screen of 71 medical plant species led to the identification of several monoterpenes with phytotoxic activity. Some of these compounds, such as β-pinene, had already been known to harbour allelopathic activity (Chowhan et al. 2013), but some were novel. Among these novel compounds, eucarvone turned out to be very promising, because it showed a pronounced species dependence of its effect. ...
Article
... ROS scavenging enzymes such as ascorbate peroxidases (APX), dehydroascorbate reductase (DHAR), and monodehydroascorbate reductase (MDHAR) were estimated according to Singh et al. (2008), , and , respectively. Lipoxygenases (LOX) activity was determined at 234 nm using an extinction coefficient (e) of 0.25 mM -1 cm -1 for linoleic acid (Chowhan et al. 2013). For determining the activities of APX and LOX, frozen root tissue was homogenized in 100 mM PO 4 3buffer (pH 7.0) in a pre-chilled pestle mortar. ...
Article
The present study investigated the effect of lead (0, 16, 40 and 80 mg L(-1) Pb(2+)) exposure for 3, 12 and 24 h on root biochemistry in hydroponically grown Zea mays (maize). Pb(2+) exposure (80 mg L(-1)) enhanced malondialdehyde content (239 %-427 %), reactive carbonyl groups (425 %-512 %) and H2O2 (129 %-294 %) accumulation during 3-24 h of treatment, thereby indicating cellular peroxidation and oxidative damage. The quantitative estimations were in accordance with in situ detection of ROS generation (using 2',7'-dichlorodihydrofluorescein diacetate dye) and H2O2 accumulation. Pb(2+) treatment significantly reduced ascorbate and glutathione content during 3-24 h of exposure. On the contrary, levels of non-protein thiols were enhanced by 3-11.8 time over control in response to 16-80 mg L(-1) Pb(2+) treatment, after 24 h. A dose-dependent induction in ascorbate peroxidase and lipoxygenase enzyme activity was observed in Z. mays roots. The activities of ascorbate-recycling enzymes (dehydroascorbate reductase and monodehydroascorbate reductase) were significantly increased in relation to concentration and duration of Pb(2+) treatment. The study concludes that Pb(2+)-exposure induces ROS-mediated oxidative damage during early period of exposure despite the upregulation of enzymes of ascorbate-glutathione cycle.
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Eryngium foetidum L. is a biennial herb belonging to the family Apiaceae, which is used extensively as a medicinal plant in most tropical regions. In this research work, the activity of the essential oil (EO) from E. foetidum against the Hyalomma lusitanicum Koch, and its phytotoxicity in germination of seeds of Lolium perenne and Lactuca sativa was studied. E. foetidum EO was isolated by the hydrodistillation technique. Gas chromatography coupled to mass spectrometry (GC-MS) was used to identify the volatile metabolites. Fifteen compounds were found in the E. foetidum EO. The major compounds were E-2-dodecenal (53.0%), trimetilbenzaldehyde (duraldehyde) (14.8%), cyclododecane (4.4%), trans-tetradec-enal (3.9%), decanal (3.6%), and trans-2-dodecen-1-ol (3.0%) and D-limonene (1.5%), respectively. The E. foetidum EO, and two of its individual main compounds (2-dodecenal, and duraldehyde) had low phytotoxic activity when were compared with the percentage of inhibition of germination of the control (carvone), in seeds of L. perenne and L. sativa. The acaricidal activity against Hyalomma lusitanicum was determined using a probit analysis (P>0.05). The essential oil of E. foetidum showed 100% mortality on H. lusitanicum at a concentration of 10 µg µL-1, and LC50 = 4.2 µg µL-1. The results obtained from the essential oil of E. foetidum show a great potential to develop natural biocides for the control of H. lusitanicum due to its chemical composition rich in aldehydes and benzene derivatives, and without adverse phytotoxic effects.
Article
The objective of this study was to explore the fungistatic mechanism of fig leaf extract against Fusarium and to provide a theoretical basis for the development of new plant-derived fungicides. Methods The fungistaticity of fig leaf extract were analyzed by the ring of inhibition method. Fusarium equiseti was selected as the target for analyzing its fungistatic mechanism in terms of mycelial morphology, ultrastructure, cell membrane permeability, membrane plasma peroxidation, reactive oxygen species (ROS) content and changes in the activity of protective enzymes. The effect of this extract was verified in melon, and its components were determined by metabolite analysis using ultraperformance liquid chromatography‒mass spectrometry (UPLC‒MS). Results Fig leaf extract had an obvious inhibitory effect on Fusarium , and the difference was significant ( P < 0.05) or highly significant ( P < 0.01). Scanning and transmission electron microscopy revealed that F. equiseti hyphae exhibited obvious folding, twisting and puckering phenomena, resulting in an increase in the cytoplasmic leakage of spores, interstitial plasma, and the concentration of the nucleus, which seriously damaged the integrity of the fungal cell membrane. This phenomenon was confirmed by propidium iodide (PI) and fluorescein diacetate (FAD) staining, cell membrane permeability and malondialdehyde (MDA) content. Fig leaf extract also induced the mycelium to produce excessive H 2 O 2 ,which led to lipid peroxidation of the cell membrane, promoted the accumulation of MDA, accelerated protein hydrolysis, induced an increase in antioxidant enzyme activity, and disrupted the balance of ROS metabolism; these findings showed that fungal growth was inhibited, which was verified in melons. A total of 1,540 secondary metabolites were detected by broad-targeted metabolomics, among which the fungistatic active substances flavonoids (15.45%), phenolic acids (15%), and alkaloids (10.71%) accounted for a high percentage and the highest relative content of these substances 1,3,7,8-tetrahydroxy-2- prenylxanthone, 8-hydroxyquinoline and Azelaic acid were analysed for their antimicrobial, anti-inflammatory, antioxidant, preventive effects against plant diseases and acquisition of resistance by plants. This confirms the reason for the fungicidal properties of fig leaf extracts. Conclusion Fig leaf extract has the potential to be developed into a plant-derived fungicide as a new means of postharvest pathogen prevention and control in melon.
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Medicinal plants have a significant role in human health care since the development of medicine. Plants that yield phytopharmaceuticals have produced a variety of compounds that benefit both humans as well as animals. With the advancement of next-generation sequencing (NGS) technologies, there is a growing interest in sequencing the genomes and transcriptomes of these life-saving plants. RNA sequencing (RNA-Seq) is one of the most advanced and powerful techniques for searching the transcripts in model as well as in non-model organisms. It is a highly sensitive, high-throughput, and high-resolution approach. In addition to analysing functional genes and regulatory mechanisms of herbal plants, transcriptomics can also aid in improving selection and cultivation methods. Even though fewer genomes have been sequenced or are being addressed, transcriptome sequencing has exponentially increased in the last couple of years, covering all important medicinal plant genera. The objective of this updated comprehensive review is to provide an overall perspective of the current status, progress, opportunities, and challenges of these sequencing efforts. In addition, a broad overview of the different generations in transcriptomics analysis, model and non-model plants that are sequenced till the year 2022, and applications of NGS in novel genes identification, their functions, as well as pathway analysis are also discussed. The information provided here emphasizes on a better understanding of the current trends and future directions in this fascinating plant genome sequencing technology.
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Preliminary phytochemical investigations were performed on the fruit essential oil and antioxidant-rich methanolic extracts of the fruits and roots of Ferula drudeana, the putative Anatolian ecotype of the Silphion plant, to corroborate its medicinal plant potential and identify its unique characteristics amongst other Ferula species. The essential oil from the fruits of the endemic species Ferula drudeana collected from Aksaray was analyzed by GC and GC/MS. The main components of the oil were determined as shyobunone (44.2%) and 6-epishyobunone (12.6%). The essential oil of the fruits and various solvent extracts of the fruits and roots of F. drudeana were evaluated for their antibacterial and anticandidal activity using microbroth dilution methods. The essential oil of the fruits, methanol, and methylene chloride extracts of the fruits and roots showed weak to moderate inhibitory activity against all tested microorganisms with MIC values of 78–2000 μg/mL. However, the petroleum ether extract of the roots showed remarkable inhibitory activity against Candida krusei and Candida utilis with MIC values of 19.5 and 9.75 μg/mL, respectively. Furthermore, all the samples were tested for their antioxidant activities using DPPH• TLC spot testing, online HPLC–ABTS screening, and DPPH/ABTS radical scavenging activity assessment assays. Methanolic extracts of the fruits and roots showed strong antioxidant activity in both systems.
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Plant-based secondary metabolites have been a major source of drug discovery and inspiration for new generations of drugs. Plants offer a wide variety of compound classes, including alkaloids, terpenes, flavonoids, and glycosides, with different molecular architectures (fused bridgehead, bi- and polycyclic, spirocyclic, polycyclic, and acyclic). The diversity, abundance, and accessibility of plant metabolites make plants an attractive source of human and animal medicine. Even though the pinene scaffold is abundant in nature and has historical use in traditional medicine, pinene and pinene-derived compounds have not been comprehensively studied for medicinal applications. This review provides insight into the utility of the pinene scaffold as a crucial building block of important natural and synthetic products and as a chiral reagent in the asymmetric synthesis of important compounds.
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Three series of secondary ammonium chloride from turpentine were synthesized and evaluated as botanical herbicides. The preemergence herbicidal activities against ryegrass (Loliun multiflorum) and barnyard grass (Echinochloa crus‐galli) were investigated using water as the only solvent. Their toxicity was evaluated by cytotoxicity assays. Preliminary results demonstrated that the herbicidal performance of the prepared salts was similar or much higher than that of corresponding secondary amines and even commercial herbicide glyphosate. Promisingly, compound 14e containing a cyclohexyl‐substituted p‐menthene skeleton with an IC50 value of 0.0014 mM against root growth of ryegrass showed 39‐fold higher herbicidal activity than glyphosate. Besides, this compound was found to be nontoxic to human and animal cells, indicating the potential application as a water‐soluble herbicide for ryegrass control.
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The mechanisms of the inhibitory action of β-pinene, a pine needle oil monoterpene, on human adenovirus type 3 were studied using cytopathic inhibition test, MTT test, atomic force and laser confocal microscopy. β-Pinene inhibited the viruses stronger that the reference antiviral medication ribavirin (p<0.05). Inhibition of viral cytopathic effect (CPE) increased with increasing the concentration of β-pinene, which attested to direct elimination of adenovirus type 3. During viral reproduction phase, β-pinene significantly inhibited proliferation of adenovirus type 3. Typical signs of adenoviral CPE as cell swelling and rounding were less pronounced in comparison with the control (ribavirin treatment). In addition, elevation of β-pinene concentration significantly increased the cell survival rate (p<0.05). Laser confocal microscopy showed that fluorescence intensity in the β-pinene group was significantly lower than in the control group (p<0.01), which was consistent with the results of MTT test, thereby providing additional arguments that β-pinene affects the virus during the absorption phase. Thus, β-pinene directly inactivates adenovirus type 3 and impedes its invasion into the cells, but produces no protective effects on cells. Understanding the mode of action of such monoterpenes as β-pinene is of great importance for the development of new antiviral drugs.
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Rice (Oryza sativa L.) is a highly consumed staple crop worldwide, but abiotic/heavy metal stresses acting on the plant cause reduction in yield and quality, thereby impacting global food security. In the present study, we examined the effect of β-pinene against Arsenic (As)-induced oxidative damage vis-à-vis regulation of activities of enzymatic antioxidants in roots of O. sativa. Effect of As (50 μM), β-pinene (10 μM; β-10) and As + β-10 treatments on root length, shoot length, As accumulation, lipid peroxidation (as malondialdehyde [MDA] content), hydrogen peroxide (H2O2) accumulation, and activities of lipoxygenase (LOX) and enzymatic antioxidants such as ascorbate peroxidase (APX), guaiacol peroxidase (GPX), glutathione reductase (GR), superoxide dismutase (SOD), and catalase (CAT) was determined. Exposure of As caused a decline in root and shoot length, and enhancement in As accumulation, lipid peroxidation, and activities of enzymatic antioxidants. However, supplementation of β-10 (i.e., As + β-10 treatments) led to an increase in root and shoot length. Treatment with As + β-10 resulted in a decline in As accumulation, H2O2 content, and MDA content; however, the effect on LOX activity was non-significant, as compared to control. Similarly, with As + β-10 treatment a reduction in the activities of APX, GPX, GR, SOD, and CAT was observed as compared with As-alone treatment. Pearson’s correlation matrix exhibited strong negative correlation between reactive oxygen species (ROS) and root/shoot length, whereas a strong positive correlation was observed between antioxidant enzymes and ROS. The present study demonstrated that β-pinene significantly ameliorates As-induced oxidative stress and provides tolerance to O. sativa against As-induced toxicity, and thus offer an option of As-mitigation using environment friendly natural plant products. However, to gain insights into the function of β-pinene in modulating As-induced oxidative damage in plants, further field investigations and exploration of its mechanism of action are needed.
Chapter
Plants produce and release into the environment many chemicals that play an important role in interindividual interactions. The majority of phytotoxins and allelochemicals of plant origin act as strong inhibitors of growth. Plant growth and architecture is regulated by phytohormones and signaling molecules such as reactive oxygen or nitrogen species (ROS/RNS). The mode of action of most phytotoxins is based on induction of secondary nitro-oxidative stress in acceptor plants, which is manifested as disturbances in the production and scavenging of ROS and/or RNS. For some allelochemicals, their impact on the metabolism of acceptor plants is well documented and includes alterations in ROS, NO, GSNO level, RNS metabolism pathways, and posttranslational modifications of proteins. We summarize data on metabolic reprogramming in plants after exposition of the plant tissue to phytotoxins, which lead to limitation or overproduction of ROS and NO. Moreover, we analyze the beneficial effect of the application of RNS donors to plants under phytotoxicity stress. In this review, we show a list of allelochemicals (or plant originated phytotoxins) that are used in pharmacology as inhibitors of NO synthase (NOS) activity in mammalian cells, and compare their mode of action in plants and animals.
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La Reserva de la Biosfera de los Valles de Omaña y Luna (Cordillera Cantábrica, León, España) ha iniciado un procedimiento para recuperar y cartografiar el patrimonio toponímico extraordinariamente rico que cubre su territorio como una malla invisible, inmaterial. Se está llevando a cabo mediante un método participativo en el que se implica a la población local. Los resultados se elevan al Instituto Geográfico Nacional y quedan incorporados en la cartografía pública disponible a través del visor Iberpix-4. Es un ejemplo de metodología para la recuperación de la toponimia como parte del patrimonio cultural inmaterial.
Chapter
Pesticides are represented by natural or chemical substances or mixtures of substances used for preventing, destroying, or controlling any pest (virucides, bactericides, fungicides, algaecides, herbicides, desiccants, insecticides, nematicides, molluscicides, rodenticides, avicides, piscicides). Despite their beneficial effects exhibited by the inhibitory effects against pests harmful for plants and animals, the chemical pesticides could also be toxic for other organisms and pollutants for the environment. Biopesticides, which are naturally occurring or derived materials from living organisms or their metabolites, have instead low negative effects as compared to chemical pesticides. Currently, under the pressing issues of food security and the need for implementation of a more sustainable agricultural system globally, there is much interest in the development of new biocontrol agents. The purpose of this chapter was to review the progress made in biopesticides development, focusing on microbial and plant-derived products and in the field of chemical pesticides biodecontamination by using microbial enzymes.
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Medicinal plants are the vital source of numerous structurally diverse pharmacologically active metabolites collectively called as secondary metabolites finding extensive applications in traditional systems of medicine and in pharmaceutical industries. Several distinctive and complex pathways operate in an interactive manner via metabolic networks that are responsible for the accumulation of such highly specialized metabolites. Secondary metabolites are believed to play a wide spectrum of physiological and functional roles in plants, many of which being investigated and supported by the experimental studies. Biosynthetic pathway related studies on various aspects in these medicinal plants have been found very tedious owing to several issues in plants such as considerably lower metabolite concentrations in native tissues, existence at different locations, and highly complex multi-step pathways, etc. Pathway elucidation and gene/enzyme discovery for studying metabolic pathway evolution and subsequent engineering could be better achieved by mining various pathway databases and reconstruction of metabolic networks available at different omics databases. Though medicinal plants have a limited range of genomic sequences available, however recently, next generation sequencing is being widely used to generate a comprehensive transcriptomic resource for these plants. It is anticipated that databases and resources generated from these studies are likely to play a key role towards the study and exploitation of metabolites from medicinal plants in near future. In this review, we have discussed next generation sequencing approaches, which were used for the generation of transcriptomic resources for several medicinally important plants. The relevance of transcriptomic approaches in curation of the pathways linked with the synthesis of major secondary metabolites along with their precursors of pharmaceutical importance in medicinal plants is also comprehensively analysed.
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The essential oils of seeds of Carum carvi was obtained by hydrodistillation with 0.74% yield on a dry weight basis. Thirty nine components were identified by GC-FID analyses. The main essential oil constituents were carvone (71.08%) and limonene (25.42%). The seed essential oil and the aqueous leaf extract of caraway were tested for their allelopathic activity in-vitro on seed germination and radicle growth. The essential oil and some of its minor constituents were effective and dose-dependent inhibitors of both germination and radicle growth. The germination and radicle growth of canary grass and wheat were most sensitive. The volatile oil > 10 mu l/ml concentrations completely inhibited the germination and radicle elongation of canary grass. We assessed the inhibitory effect of extract at different concentrations on germination and radicle elongation of wheat, maize, flax and canary grass. The germination of canary grass and wheat was significantly decreased at 6.5g/100 ml. All concentrations of extract sreduced the radicle elongation of flax. The total phenolics content was 6.42 to 11.21 mg/g in dry weight of extract, expressed as gallic acid equivalents. The total flavonoids were 2.14 to 1.89 mg/g, expressed as queicetin equivalents. Methanolic extract of C. carvi showed the highest phenolic and flavonoid concentration.
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The allelopathic effects of 3-relatively abundant volatile compounds [n-octane, 2,4-di-tert-butyl phenol and 2,2 '-methylene bis (6-tert-butyl-4-methyl phenol)] present in the soil of Eucalyptus granclis plantation (1-10 years old) were studied on the seed germination, seedling growth and two physiological indicators [(seedling's malondialdehyde (MDA) and roots' vitality (by triphenyl tetrazolium chloride (TTC)] of Vigna radiata, Raphanus sativus and Lactuca sativa. The inhibitory effects of 2, 4-di-tert-butyl phenol was strongest on the target plants. The three volatile compounds at high concentrations [n-octane, 1%; 2,4-di-tert-butyl phenol, 10 mmol/E; 2,2 '-methylene bis (6-tert-butyl-4-methyl phenol)], 10 mmol/E) inhibited the seed germination, root length, seedling height and the seedling / root fresh weight ratio of Vigna radiata, Raphanus sativus and Lactuca sativa, but low concentrations were less inhibitory or stimulatory. All three volatile compounds at low concentrations were slightly stimulatory to seedling's MDA content and were less inhibitory to seedlings roots' vitality TTC. At low concentrations, the n-octane and 2, 2'-methylene bis (6-tert-butyl -4- methyl phenol) were less stimulatory to the seedlings root's vitality. However, 2, 2'-methylene bis (6-tert-butyl -4- methyl phenol) even at lower concentrations inhibited the V. radiata seedling's MDA content
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Plant tissue culture technique could provide sterile and controllable condition in order to assay direct effect of different compounds on plant growth accurately. In this study, the effects of aqueous extracts prepared from roots and shoots of goosefoot (Chenopodium album L.), redroot pigweed (Amaranthus retroflexus L.), fennel (Foeniculum vulgare), and wormwood (Artemisia absinthium L.) were evaluated on the seed germination and growth criteria in tissue culture media. The fennel root extract, nearly without phenolic content and with low antioxidant activity, showed the most drastic allelopathic effect on goosefoot, especially at 100 mg mL-1 concentration, which might be due to the presence of some substance potentially useful for biological control of goosefoot, an invasive weed. Goosefoot was resistant to extract of fennel shoot, wormwood root, and shoot, while fennel and radish (Raphanus sativus L.), at high concentration (100 mg mL-1), were not resistant to the root and shoot extracts of both goosefoot and redroot pigweed. In response to allelopathic components, shoot:root ratio was increased, and more peroxidase and superoxide dismutase activity were detected in roots. There was no direct relationship between allelopathic effects with total phenolic content and antioxidant activity. In conclusion, our results showed that allelopathic effects of extracts on growth and biochemical criteria depended on both the concentration levels and the plant parts from which the aqueous extract was derived. Therefore, tissue culture media is an accurate and suitable tool to screen plants resistant to allelopathic components of weeds, and to identify high allelopathic plants as potential bioherbicide and invasive plant controller.
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Natural products represent a vast repository of materials and compounds with evolved biological activity, including phytotoxicity. Some of these compounds can be used directly or as templates for herbicides. The molecular target sites of these compounds are often unique. Strategies for the discovery of these materials and compounds are outlined. Numerous examples of individual phytotoxins and crude preparations with weed management potential are provided. An example of research to find a natural product solution of a unique pest management problem (blue-green algae in aquaculture) is described. Finally, the problems associated with natural products for pest control are discussed.
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The potential use of natural phytotoxins (including allelochemicals) to develop novel tools for weed management is enhanced by the elucidation of their modes of action. This approach has not been emphasized by the agrochemical industry, although the possibility of discovering new target sites may be promising, since natural products tend to have modes of action different from synthetic herbicides. The approach of testing a compound on all known herbicide molecular target sites for commercial herbicides and other potent phytotoxins is feasible. However, this would preclude the discovery of new mechanisms of action. Discovering new target sites requires more challenging holistic approaches, initiated with physiological and biochemical studies that use whole plant assays. Studying basic plant responses to a compound may yield important clues to the specific physiological processes affected by the compounds and uncover novel mechanisms of action.
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Arsenic (As) toxicity and its biochemical effects have been mostly evaluated in ferns and a few higher plants. In this study, we investigated the effect of As (10.0 and 50.0μM) on seedling growth, root anatomy, lipid peroxidation (malondialdehyde and conjugated dienes), electrolyte leakage, H2O2 content, root oxidizability and the activities of antioxidant enzymes in mung bean (Phaseolus aureus Roxb.). Arsenic significantly enhanced lipid peroxidation (by 52% at 50.0μM As), electrolyte leakage and oxidizability in roots. However, there was no significant change in H2O2 content. Arsenic toxicity was associated with an increase in the activities of superoxide dismutase (SOD), guaiacol peroxidase (GPX) and glutathione reductase (GR). In response to 50.0μM As, the activities of SOD and GR increased by over 60% and 90%, respectively. At 10.0μM As, the activity of ascorbate peroxidase (APX) increased by 83%, whereas at 50.0μM it declined significantly. The catalase (CAT) activity, on the other hand, decreased in response to As exposure, and it corresponded to the observed decrease in H2O2 content. We conclude that As causes a reduction in root elongation by inducing an oxidative stress that is related to enhanced lipid peroxidation, but not to H2O2 accumulation.
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The effects of select monoterpenes on nitrogen (N) mineralization and nitrification potentials were determined in four separate laboratory bioassays. The effect of increasing monoterpene addition was an initial reduction in NO3 –-N production (nitrification inhibition), followed by a reduction in the sum of NH4 +-N and NO3 –-N (inhibition of net N mineralization and net immobilization at high monoterpene additions. Monoterpenes could produce this pattern by inhibiting nitrification, reducing net N mineralization, enhancing immobilization of NO3 –-N relative to NH4 +-N, and/or stimulating overall net immobilization of N by carbon-rich material.Initial monoterpene concentrations in the assay soils were about 5% of the added amount and were below detection after incubation in most samples.Potential N mineralization-immobilization, nitrification, and soil monoterpene concentrations were determined by soil horizon for four collections from a ponderosa pine (Pinus ponderosa) stand in New Mexico. Concentrations of monoterpenes declined exponentially with soil depth and varied greatly within a horizon. Monoterpene content of the forest floor was not correlated with forest floor biomass. Net N mineralization was inversely correlated with total monoterpene content of all sampled horizons. Nitrification was greatest in the mineral soil, intermediate in the F-H horizon, and never occurred in the L horizon. Nitrification in the mineral soil was inversely correlated with the amount of monoterpenes in the L horizon that contain terminal unsaturated carbon-carbon bonds (r 2 = 0.37, P 0.01). This pattern in the field corresponded to the pattern shown in the laboratory assays with increasing monoterpene additions.
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The essential oils from the aerial parts of catmint (Nepeta meyeri Benth.) were analyzed by hydrodistillation with GC-MS. Fourteen compounds were identified in the yellowish essential oil of the plant, representing more than 99.07% of the oil, of which the major components were found to be 4a alpha,7 alpha,7a beta-nepetalactone (83.4%) and 4a alpha,7 alpha,7a alpha-nepetalactone (8.83%). The oils were characterized by relatively high content of oxygenated monoterpenes, and were tested on the germination and antioxidative systems in early seedlings of seven weed species (Amaranthus retroflexus L., Bromus danthoniae Trin., Bromus intermedius Guss., Chenopodium album L., Cynodon dactylon L., Lactuca serriola L., and Portulaca oleracea L.) and autotoxicity. The essential oil of N. meyeri inhibited seed germination by more than 50% in three weed species (B. danthoniae, B. intermedius, and L. serriola) when applied at a concentration of 0.01%. When the same oils were applied at 0.02% concentration, the inhibition of germination was more than 70% in two weeds (C. album and C. dactylon) and was 100% in four weeds (A. retroflexus, B. danthoniae, B. intermedius, and L. serriola). The essential oils increased CAT activity in all the weed species and decreased SOD activity, except in A. retroflexus. POX activity did not exhibit a revealing situation in the weed species tested. The essential oils increased the level of lipid peroxidation and hydrogen peroxide (H2O2) concentration in all the weeds studied. Our results show that the essential oils of N. meyeri have an important phytotoxic effect on seed germination and, consequently, seedling growth by exhausting antioxidative system of the weeds. The phytotoxic activity of the essential oils may be attributed to their relatively high content of oxygenated monoterpenes, especially 4a alpha,7 alpha,7a beta-nepetalactone. It can be suggest that the essential oils of N. meyeri have the potential to be used as a bioherbicide.
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Changes in soluble and cell wall bound peroxidase (POD, EC 1.11.1.7) activity, phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) activity, and lignin content in roots of ferulic acid-stressed soybean (Glycine max (L.) Merr.) seedlings and their relationships with root growth were investigated. Three-day-old soybean seedlings were cultivated in half-strength Hoagland nutrient solution containing 1.0 mM ferulic acid for 24-72 hr. Length, fresh weight, and dry weight of roots decreased, while soluble and cell wall bound POD activity, PAL activity, and lignin content increased after ferulic acid treatment. These enzymes probably participate in root growth reduction in association with cell wall stiffening related to the formation of cross-linking among cell wall polymers and lignin production.
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Eucalyptus (family Myrtaceae), an Australian native, represented by around 700 species is a genus of tall, evergreen and magnificent trees cultivated world over for its oil, gum, pulp, timber, medicine and aesthetic value. Among the various wood and non-wood products, essential oil found in its foliage is the most important one and finds extensive use in food, perfumery and pharmaceutical industry. In addition, the oil possesses a wide spectrum of biological activity including anti-microbial, fungicidal, insecticidal/insect repellent, herbicidal, acaricidal and nematicidal. The present paper discusses this environmentally benign pest control using eucalyptus oils against bacteria, fungi, insects, nematodes, weeds and mites. The use of eucalyptus oil as a natural pesticide is of immense significance in view of the environmental and toxicological implications of the indiscriminate use of synthetic pesticides and overcoming/reducing the problem of increasing pest resistance.
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Twenty common plant species were screened for emissions of biogenic volatile organic compounds (BVOCs) at a lowland tropical wet forest site in Costa Rica. Ten of the species examined emitted substantial quantities of isoprene. These species accounted for 35–50% of the total basal area of old-growth forest on the major edaphic site types, indicating that a high proportion of the canopy leaf area is a source of isoprene. A limited number of canopy-level BVOC flux measurements were also collected by relaxed eddy accumulation (REA). These measurements verify that the forest canopy in this region is indeed a significant source of isoprene. In addition, REA fluxes of methanol and especially acetone were also significant, exceeding model estimates and warranting future investigation at this site. Leaf monoterpene emissions were non-detectable or very low from the species surveyed, and ambient concentrations and REA fluxes likewise were very low. Although the isoprene emission rates reported here are largely consistent with phylogenetic relations found in other studies (at the family, genus, and species levels), two species in the family Mimosaceae, a group previously found to consist largely of non-isoprene emitters, emitted significant quantities of isoprene. One of these, Pentaclethra macroloba (Willd.) Kuntze, is by far the most abundant canopy tree species in the forests of this area, composing 30–40% of the total basal area. The other, Zygia longifolia (Humb. & Bonpl.) Britton & Rose is a common riparian species. Our results suggest that the source strength of BVOCs is important not only to tropical atmospheric chemistry, but also may be important in determining net ecosystem carbon exchange.
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Numerical assessments of global air quality and potential changes in atmospheric chemical constituents require estimates of the surface fluxes of a variety of trace gas species. We have developed a global model to estimate emissions of volatile organic compounds from natural sources (NVOC). Methane is not considered here and has been reviewed in detail elsewhere. The model has a highly resolved spatial grid (0.5 degrees x 0.5 degrees latitude/longitude) and generates hourly average emission estimates. Chemical species are grouped into four categories: isoprene, monoterpenes, other reactive VOC (ORVOC), and other VOC (OVOC). NVOC emissions from oceans are estimated as a function of geophysical variables from a general circulation model and ocean color satellite data. Emissions from plant foliage are estimated from ecosystem specific biomass and emission factors and algorithms describing light and temperature dependence of NVOC emissions. Foliar density estimates are based on climatic variables and satellite data. Temporal variations in the model are driven by monthly estimates of biomass and temperature and hourly light estimates. The annual global VOC flux is estimated to be 1150 Tg C, composed of 44% isoprene, 11% monoterpenes, 22.5% other reactive VOC, and 22.5% other VOC. Large uncertainties exist for each of these estimates and particularly for compounds other than isoprene and monoterpenes. Tropical woodlands (rain forest, seasonal, drought-deciduous, and savanna) contribute about half of all global natural VOC emissions. Croplands, shrublands and other woodlands contribute 10-20% apiece. Isoprene emissions calculated for temperate regions are as much as a factor of 5 higher than previous estimates.
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Volatile compounds act as a language that plants use for their communication and interaction with the surrounding environment. To date, a total of 1700 volatile compounds have been isolated from more than 90 plant families. These volatiles, released from leaves, flowers, and fruits into the atmosphere and from roots into the soil, defend plants against herbivores and pathogens or provide a reproductive advantage by attracting pollinators and seed dispersers. Plant volatiles constitute about 1% of plant secondary metabolites and are mainly represented by terpenoids, phenylpropanoids/benzenoids, fatty acid derivatives, and amino acid derivatives. In this review we focus on the functions of plant volatiles, their biosynthesis and regulation, and the metabolic engineering of the volatile spectrum, which results in plant defense improvement and changes of scent and aroma properties of flowers and fruits.
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This work was carried out to adapt the electrolyte leakage technique todurum wheat and then to evaluate its relevance in the assessment of the cellmembrane stability as a mechanism of water stress tolerance in this species.Themethod currently used is based on in vitro desiccation ofleaf tissues by a solution of polyethylene glycol (PEG) and a subsequentmeasurement of electrolyte leakage into deionised water. It consists of threesuccessive steps: (1) a washing treatment to remove solutes from both leafsurfaces and cells damaged by cutting; (2) a stress period during which theleaftissues are plunged in a PEG-solution and (3) a rehydration period during whichafter-effects of the stress are evaluated. During the washing period, the majorpart of electrolytes was removed within 15 min. Varying the stressconditions influenced both the percent and the kinetics of electrolyte leakageduring rehydration. Electrolyte leakage exhibited a characteristic patternreflecting the condition of cellular membranes (repair and hardening). Inpractice, we recommend a 15-minute washing time, a10-hour stress period and 4 h of rehydration. Theextent of the cell membrane damage not only correlated well with the growthresponses of wheat seedlings belonging to various cultivars to withholdingwaterbut also with the recognised field performances of these cultivars. Therelativeproportion of endogenous ions lost in the effusate during the rehydration stepmay vary strongly according to the element analysed and the precise nutritionalstatus of the plant should therefore be considered. However, an increase ininorganic ion leakage does not fully explain the recorded PEG-induced increasein electrical conductivity (EC) during the subsequent rehydration step andorganic ions are probably also involved in such an increase.
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Volatile monoterpenes such as 1,8-cineole inhibit the growth of Brassica campestris seedlings in a dose-dependent manner, and the growth-inhibitory effects are more severe for roots than hypocotyls. The preferential inhibition of root growth may be explained if the compounds inhibit cell proliferation more severely than cell elongation because root growth requires both elongation and proliferation of the constituent cells, whereas hypocotyl growth depends exclusively on elongation of existing cells. In order to examine this possibility, BY-2 suspension-cultured tobacco (Nicotiana tabacum) cells were treated with 1,8-cineole, and the inhibitory effects on cell proliferation and on cell elongation were assessed quantitatively. Treatment with 1,8-cineole lowered both the mitotic index and elongation of the cells in a dose-dependent manner, and the half-maximal inhibitory concentration (IC₅₀) for cell elongation was lower than that for cell proliferation. Moreover, 1,8-cineole also inhibited starch synthesis, with IC₅₀ lower than that for cell proliferation. Thus, the inhibitory effects of 1,8-cineole were not specific to cell proliferation; rather, 1,8-cineole seemed inhibitory to a variety of physiological activities when it was in direct contact with target cells. Based on these results, possible mechanisms for the mode of action of 1,8-cineole and for its preferential inhibition on root growth are discussed.
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When titanium dioxide (TiO(2)) is irradiated with near-UV light, this semiconductor exhibits strong bactericidal activity. In this paper, we present the first evidence that the lipid peroxidation reaction is the underlying mechanism of death of Escherichia coli K-12 cells that are irradiated in the presence of the TiO(2) photocatalyst. Using production of malondialdehyde (MDA) as an index to assess cell membrane damage by lipid peroxidation, we observed that there was an exponential increase in the production of MDA, whose concentration reached 1.1 to 2.4 nmol. mg (dry weight) of cells(-1) after 30 min of illumination, and that the kinetics of this process paralleled cell death. Under these conditions, concomitant losses of 77 to 93% of the cell respiratory activity were also detected, as measured by both oxygen uptake and reduction of 2,3,5-triphenyltetrazolium chloride from succinate as the electron donor. The occurrence of lipid peroxidation and the simultaneous losses of both membrane-dependent respiratory activity and cell viability depended strictly on the presence of both light and TiO(2). We concluded that TiO(2) photocatalysis promoted peroxidation of the polyunsaturated phospholipid component of the lipid membrane initially and induced major disorder in the E. coli cell membrane. Subsequently, essential functions that rely on intact cell membrane architecture, such as respiratory activity, were lost, and cell death was inevitable.
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Differential activities of BOA, DIBOA, and crude water extract of Secale cereale ‘Elbon’ were studied in culture dish bioassays using several vegetable and weed species. On average, DIBOA was about seven times more inhibitory to root growth and four times more inhibitory to shoot growth than BOA. Allelochemicals from S. cereale inhibited shoot more than root elongation of cucurbits Cucumis melo, Cucumis sativus, and Cucurbita pepo. Small-seeded crops Lycopersicon esculentum and Lactuca sativa were sensitive to S. cereale. Large-seeded crops, including the cucurbits and Zea mays var. rogusa, were tolerant. Among the small-seeded weeds Amaranthus palmeri, Digitaria sanguinalis, Echinochloa crus-galli, and Eleusine indica, E. crus-galli was least susceptible. Inhibition of germination by BOA or DIBOA occurred only in small- to medium-seeded species, including A. palmeri, D. sanguinalis, E. indica, L. sativa, L. esculentum, and Sida spinosa. Large-seeded species C. melo, C. sativus, C. melopepo, Z. mays var. rogusa, Ipomoea hederacea var. integriuscula, Ipomoea lacunosa, and Senna obtusifolia were tolerant to allelochemicals from S. cereale. This bioassay indicated a promising potential for controlling small-seeded weeds in large-seeded crops.
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Caffeic acid, chlorogenic acid, coumarin, p -coumaric acid, ferulic acid, fumaric acid, gallic acid, hydrocinnamic acid, p -hydroxybenzoic acid, juglone, and pyrocatechol were examined for effects on germination of nine crop and weed species: cotton ( Gossypium hirsutum L.), cantaloupe ( Cucumis melo L.), corn ( Zea mays L.), sorghum [ Sorghum bicolor (L.) Moench], hemp sesbania [ Sesbania exaltata (Raf.) Cary], sicklepod ( Cassia obtusifolia L.), velvetleaf ( Abutilon theophrasti Medic), prickly sida ( Sida spinosa L.), and redroot pigweed ( Amaranthus retroflexus L.). Germination tests with 10- ³ and 10- ⁵ M solutions were conducted under controlled conditions in petri dishes at 25 C in the dark. At 10- ³ M, coumarin, hydrocinnamic acid, juglone and pyrocatechol inhibited germination, but p -hydroxybenzaldehyde and p -hydroxybenzoic acid were not effective and others had intermediate effects. There was little effect by any compound at 10- ⁵ M. Chlorogenic acid, p -hydroxybenzaldehyde, and pyrocatechol, each combined with coumarin, inhibited germination. The combination of coumarin plus p -hydroxybenzaldehyde had an additive effect on hemp sesbania and prickly sida, inhibiting germination to a greater extent than either compound alone. The lack of inhibitory action at the higher concentration of some of these chemicals suggests they may not exhibit a high allelopathic potential.
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Gas chromatography studies have shown that the air around Salvia leucophylla and S. mellifera (growing either in the field or in the greenhouse) contains two terpenes, apparently cineole and camphor. These terpenes are known to be more toxic than other terpenes that occur in the plants. The several terpenes of S. leucophylla are highly soluble in hard paraffin, suggesting that they are taken into the seedlings they inhibit by solution in the cutin of the mesophyll.
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A chloroplast preparation was extracted from squash (Cucurbita pepo (L.) var. Senator). Enrichment of intact chloroplasts was achieved by continuous free-flow electrophoresis. The addition of monoterpenes, detergent and free fatty acids changed the elecrophoretic separation pattern characteristically. Monoterpene-dependent degradation of envelope membranes could be prevented by addition of α-tocopherol prior to monoterpene incubation. Photosynthetic electron transport of photosystem II was completely inhibited by β-pinene, Triton X-100 and linolenic acid. Inhibition could be modulated by addition of α-tocopherol or lecithin (phosphatidylcholine) either before or after inhibition by monoterpenes and detergent. Percentage reconstitution of photosynthetic electron transport inhibited by β-pinene depended on light conditions and incubation time.
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This article explores the evidence for monoterpenes to alter rates of nutrient cycling, with particular emphasis on the nitrogen (N) cycle, from an ecosystem perspective. The general N cycle is reviewed and particular processes are noted where monoterpenes could exert control. The theoretical and conceptual basis for a proposed mode of action by which monoterpenes effect the processes of N mineralization and nitrification is presented, along with recent developments. It is hypothesized that monoterpenes retained in litter enhance the frequency of fire, which in turn changes many N-cycling processes. Experimental support for these roles is presented that includes effects at the cellular level and progresses through populations and communities (microbial and invertebrate) involved in N mineralization and immobilization processes. Since many inhibitors of ammonium oxidation also inhibit methane oxidation, monoterpenes also may alter processes within the carbon cycle. Finally, areas for future research that appear most promising are suggested.
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1. Oxygen is a toxic gas - an introductionto oxygen toxicity and reactive species 2. The chemistry of free radicals and related 'reactive species' 3. Antioxidant defences Endogenous and Diet Derived 4. Cellular responses to oxidative stress: adaptation, damage, repair, senescence and death 5. Measurement of reactive species 6. Reactive species can pose special problems needing special solutions. Some examples. 7. Reactive species can be useful some more examples 8. Reactive species can be poisonous: their role in toxicology 9. Reactive species and disease: fact, fiction or filibuster? 10. Ageing, nutrition, disease, and therapy: A role for antioxidants?
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β-Pinene, an oxygenated monoterpene, is one of the major monoterpenes emitted into the atmosphere from forest areas and trees. Besides, it is a principal component of essential oils of a number of aromatic plants, which are involved in a variety of ecological interactions, including allelopathy, in the natural environment. However, studies pertaining to phytotoxicity and biochemical effect(s) of β-pinene are largely lacking. We investigated the effect of β-pinene (0.02, 0.04, 0.08, 0.20, 0.40 and 0.80 mg/ml) in a dose- and time-dependent manner on early seedling growth, dry weight accumulation, photosynthetic pigments and changes in macromolecule (protein and carbohydrate) content and activities of enzymes—proteases, α- and β-amylases, polyphenol oxidases and peroxidases- in rice (Oryza sativa) after 3rd, 5th and 7th day of exposure. β-pinene (≥0.04 mg/ml) significantly reduced the root (by 13–87%) and coleoptile (by 5–80%) length of rice. Exposure to β-pinene reduced total chlorophyll content in rice coleoptiles suggesting a negative impact on photosynthesis. The content of macromolecules (proteins and carbohydrates) enhanced significantly in response to β-pinene, whereas the activities of hydrolyzing enzymes—proteases, α-amylases, and β-amylases—declined (by 30–85, 26–84, 27–74%, respectively) in β-pinene-exposed seedlings. In contrast, the activities of peroxidases (POX) and polyphenol oxidases (PPO) enhanced significantly (by 16–152 and 53–290%, respectively) in rice roots in response to β-pinene in a dose- and time-dependent manner. Increased activities of POX and PPO indicate their involvement in providing protection and/or conferring resistance against β-pinene-induced stress. The study concludes that β-pinene inhibits the early growth of rice by altering the plant biochemical status and enhancing activities of POXs and PPOs involved in general plant defense.
Article
A study was conducted to assess the bioherbicidal activity of volatile oil hydrodistilled from Artemisia scoparia Waldst et Kit. (red stem wormwood; Asteraceae) against five weed species, viz. Achyranthes aspera, Cassia occidentalis, Parthenium hysterophorus, Echinochloa crus-galli, and Ageratum conyzoides. Emergence and seedling growth (in terms of root and shoot length) were significantly reduced in a dose–response bioassay conducted in sand impregnated with Artemisia oil (at ≥10, 25, and 50μg Artemisia oil/g sand). In general, the root length was inhibited more as compared to the shoot length and the inhibitory effect was greatest in P. hysterophorus followed by A. conyzoides and least in C. occidentalis. Post-emergence application of Artemisia oil (2%, 4%, and 6%, v/v) on 6-week-old weed plants caused visible injury (1- and 7-days after spray) ranging from chlorosis to necrosis to complete wilting of plants. Among the sprayed test weeds, the effect was greatest on E. crus-galli and P. hysterophorus. Artemisia oil treatment resulted in a loss of chlorophyll content and cellular respiration in test weeds thereby implying interference/impairment with photosynthetic and respiratory metabolism. Artemisia oil caused a severe electrolyte leakage from E. crus-galli (a monocot) and C. occidentalis (a dicot) indicating membrane disruption and loss of integrity. The study concludes that Artemisia oil has bioherbicidal properties as it causes severe phytotoxicity and interferes with the growth and physiological processes of some weed species.
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Anoxia followed by reoxygenation causes extensive damage to cellular components through generation of reactive oxygen intermediates. We examined cellular responses to oxidative stress after anoxia in cultured soybean or human fibroblast cells. Anoxia pretreatment protected soybean but not fibroblasts against H2O2 concentrations that induced programmed cell death in normoxic cells. H2O2 removal in anoxia-pretreated soybean cultures was faster. Protection was associated with increased action of alternative oxidase (AOX) and peroxidases. AOX inhibitors abolished the protective effect, while induction of AOX protected normoxic cells against H2O2. We propose that during anoxia, plant cells can prepare for reoxygenation injury by up-regulating their antioxidant capacity, and that AOX is involved in this process.
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Weeds are known to cause enormous losses due to their interference in agroecosystems. Because of environmental and human health concerns, worldwide efforts are being made to reduce the heavy reliance on synthetic herbicides that are used to control weeds. In this regard the phenomenon of allelopathy, which is expressed through the release of chemicals by a plant, has been suggested to be one of the possible alternatives for achieving sustainable weed management. The use of allelopathy for controlling weeds could be either through directly utilizing natural allelopathic interactions, particularly of crop plants, or by using allelochemicals as natural herbicides. In the former case, a number of crop plants with allelopathic potential can be used as cover, smother, and green manure crops for managing weeds by making desired manipulations in the cultural practices and cropping patterns. These can be suitably rotated or intercropped with main crops to manage the target weeds (including parasitic ones) selectively. Even the crop mulch/residues can also give desirable benefits. Not only the terrestrial weeds, even allelopathy can be suitably manipulated for the management of aquatic weeds. The allelochemicals present in the higher plants as well as in the microbes can be directly used for weed management on the pattern of herbicides. Their bioefficacy can be enhanced by structural changes or the synthesis of chemical analogues based on them. Further, in order to enhance the potential of allelopathic crops, several improvements can be made with the use of biotechnology or genomics and proteomics. In this context either the production of allelochemicals can be enhanced or the transgenics with foreign genes encoding for a particular weed-suppressing allelochemical could be produced. In the former, both conventional breeding and molecular genetical techniques are useful. However, with conventional breeding being slow and difficult, more emphasis is laid on the use of modern techniques such as molecular markers and the selection aided by them. Although the progress in this regard is slow, nevertheless some promising results are coming and more are expected in future. This review attempts to discuss all these aspects of allelopathy for the sustainable management of weeds. Referee: Dr. Amrjits S. Basra, Central Plains Crop Technology, 5912 North Meridian Avenue, Wichita, KS 67204
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Differential activities of BOA, DIBOA, and crude water extract of Secale cereale ‘Elbon’ were studied in culture dish bioassays using several vegetable and weed species. On average, DIBOA was about seven times more inhibitory to root growth and four times more inhibitory to shoot growth than BOA. Allelochemicals from S. cereale inhibited shoot more than root elongation of cucurbits Cucumis melo, Cucumis sativus, and Cucurbita pepo. Small-seeded crops Lycopersicon esculentum and Lactuca sativa were sensitive to S. cereale. Large-seeded crops, including the cucurbits and Zea mays var. rogusa, were tolerant. Among the small-seeded weeds Amaranthus palmeri, Digitaria sanguinalis, Echinochloa crus-galli, and Eleusine indica, E. crus-galli was least susceptible. Inhibition of germination by BOA or DIBOA occurred only in small- to medium-seeded species, including A. palmeri, D. sanguinalis, E. indica, L. sativa, L. esculentum, and Sida spinosa. Large-seeded species C. melo, C. sativus, C. melopepo, Z. mays var. rogusa, Ipomoea hederacea var. integriuscula, Ipomoea lacunosa, and Senna obtusifolia were tolerant to allelochemicals from S. cereale. This bioassay indicated a promising potential for controlling small-seeded weeds in large-seeded crops. Nomenclature:BOA, (3H)-benzoxazolinone; DIBOA, 2,4-dihydroxy-1,4-(2H)benzoxazine-3-one; Echinochloa crus-galli L. Beauv. ECHCG, barnyardgrass; Ipomoea hederacea var. integriuscula L. IPOHE, entireleaf morningglory; Eleusine indica L. Gaertn. ELEIN, goosegrass; Digitaria sanguinalis L. Scop. DIGSA, large crabgrass; Amaranthus palmeri S. Wats. AMAPA, Palmer amaranth; Ipomoea lacunosa L. IPOLA, pitted morningglory; Sida spinosa L. SIDSP, prickly sida; Senna obtusifolia L. CASOB, sicklepod; Cucumis melo L., cantaloupe; Cucumis sativus L., cucumber; Lactuca sativa L., lettuce; Secale cereale L., rye; Cucurbita pepo var. melopepo L. cv. Alef., summer squash; Zea mays var. rogusa Bonaf, sweet corn; Lycopersicon esculentum Mill., tomato.
Article
Laboratory and greenhouse experiments were conducted to determine the herbicidal effect of plant-derived oils and to identify the active ingredient in an oil with herbicide activity. Twenty-five different oils were applied to detached leaves of dandelion in the laboratory. Essential oils (1%, v/v) from red thyme, summer savory, cinnamon, and clove were the most phytotoxic and caused electrolyte leakage resulting in cell death. Each of these essential oils in aqueous concentrations from 5 to 10% (v/v) plus two adjuvants (nonionic surfactant and paraffinic oil blend at 0.2% [v/v]) were applied to shoots of common lambsquarters, common ragweed, and johnsongrass in the greenhouse; shoot death occurred within 1 h to 1 d after application. Essential oil of cinnamon had high herbicidal activity, and eugenol (2-methoxy-4-[2-propenyl]phenol) was determined to be this oil's major component (84%, v/v). Dandelion leaf disk and whole-plant assays verified that eugenol was the active ingredient in the essential oil of cinnamon. Essential oils are extracted from plants and thus may be useful as “natural product herbicides” for organic farming systems. Nomenclature: Cinnamon, Cinnamomum zeylanicum; clove, Syzgium aromaticum; red thyme, Thymus vulgaris; summer savory, Satureja hortensis; common lambsquarters, Chenopodium album L. CHEAL; common ragweed, Ambrosia artemisiifolia L. AMBEL; dandelion, Taraxacum officinale Weber in Wiggers TAROF; johnsongrass, Sorghum halepense (L.) Pers. SORHA.
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Herbicidal activities of clove oil and its primary constituent eugenol on broccoli, common lambsquarters, and redroot pigweed and the role of crystalline leaf epicuticular wax (LEW) in susceptibility and retention of these essential oils were studied. Clove oil (2.5%) and eugenol (1.5%) were applied to leaves of greenhouse-grown broccoli, common lambsquarters, and redroot pigweed seedlings and effects on seedling growth and leaf cell membrane integrity were studied. Compared with eugenol, clove oil caused greater inhibition of seedling growth in all species. Both eugenol and clove oil caused greater loss of membrane integrity and inhibition of seedling growth in redroot pigweed, which has no crystalline LEW, compared with common lambsquarters, which has a thick layer of crystalline LEW. In broccoli seedlings with LEW, clove oil caused greater inhibition of growth than eugenol. Both clove oil and eugenol caused greater electrolyte leakage from broccoli leaves without LEW than in the leaves with LEW. Removal of LEW increased electrolyte leakage, an indicator of cell membrane damage, by 97% in eugenol-treated and 26% in clove oil–treated broccoli leaves. Susceptibility of broccoli seedlings and possibly some weed species may, therefore, be affected by factors (e.g., genetic, environmental) that influence the amount of LEW. Although the presence of LEW greatly reduced the retention of the essential oil solutions, there was no significant difference between the retention of clove oil and eugenol solutions, indicating that differences in their phytotoxicity to broccoli leaves was not due to differential foliar retention. Nomenclature: Common lambsquarters, Chenopodium album L. CHEAL; redroot pigweed, Amaranthus retroflexus L. AMARE; clove, Syzygium aromaticum (L.) Merr. & Perr.; purple sprouting broccoli, Brassica oleracea var. italica.
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Free radicals and other active derivatives of oxygen are inevitable by-products of biological redox reactions. Reduced oxygen species, such as hydrogen peroxide, the superoxide radical anion and hydroxyl radicals, inactivate enzymes and damage important cellular components. In addition, singlet oxygen, produced via formation of triplet state chlorophyll, is highly destructive. This oxygen species initiates lipid peroxidation, and produces lipid peroxy radicals and lipid hydroperoxides that are also very reactive. The increased production of toxic oxygen derivatives is considered to be a universal or common feature of stress conditions. Plants and other organisms have evolved a wide range of mechanisms to contend with this problem. The antioxidant defence system of the plant comprises a variety of antioxidant molecules and enzymes. Considerable interest has been focused on the ascorbate-glutathione cycle because it has a central role in protecting the chloroplasts and other cellular compartments from oxidative damage. It is clear that the capacity and activity of the antioxidative defence systems are important in limiting photo-oxidative damage and in destroying active oxygen species that are produced in excess of those normally required for signal transduction or metabolism. In our studies on this system, we became aware that the answers to many unresolved questions concerning the nature and regulation of the antioxidative defence system could not be obtained easily by either a purely physiological or purely biochemical approach. Transgenic plants offered us a means by which to achieve a more complete understanding of the roles of the enzymes involved in protection against stress of many types: environmental and man-made. The ability to engineer plants which express introduced genes at high levels provides an opportunity to manipulate the levels of these enzymes, and hence metabolism in vivo. Studies on transformed plants expressing increased activities of single enzymes of the antioxidative defence system indicate that it is possible to confer a degree of tolerence to stress by this means. However, attempts to increase stress resistance by simply increasing the activity of one of the antioxidant enzymes have not always been successful presumably because of the need for a balanced interaction of protective enzymes. The study of these transformed plants has allowed a more complete understanding of the roles of individual enzymes in metabolism. Protection against oxidative stress has become a feasible objective through the application of molecular genetic techniques in conjunction with a biochemical and physiological approach.
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The effect of four monoterpenes - citronellol, citronellal, cineole and linalool - on the germination, growth and physiology of Cassia occidentalis was investigated. All four monoterpenes reduced germination of C. occidentalis seeds but to varying extents. Citronellal and linalool completely inhibited germination beyond the concentrations of 55 and 110 μM, respectively, whereas in response to treatment of citronellol no germination was observed beyond 330 μM. Further, the growth of seedlings, measured in terms of seedling length and biomass, was also adversely affected. A reduction in chlorophyll content of the cotyledonary leaves of C. occidentalis was also noticed, indicating an adverse effect on photosynthesis. Likewise, respiratory ability of growing seeds was also impaired in response to all four monoterpenes, clearly indicating that monoterpenes affect energy metabolism. On the basis of overall phytotoxicity, potency of monoterpenes was in the order of citronellal > linalool > citronellol > cineole. The results from this study suggest that both citronellal and linalool possess strong phytotoxic potential and can thus serve as lead molecules for the synthesis of bioherbicides.
Article
The volatile monoterpene analogs, 1,4-cineole and 1,8-cineole, have been identified as components of many plant essential oils, but relatively little is known about their biological activities. We compared the effects of 1,4- and 1,8-cineole on two weedy plant species by monitoring germination, mitosis, root and shoot growth, chlorophyll content, and photosynthetic efficiency. 1,4-Cineole severely inhibited growth of roots and shoots, causing cork-screw shaped morphological distortion, whereas 1,8-cineole caused a decrease in root growth and germination rates. Chlorophyll fluorescence data (yield and F v / F m) indicated that 1,4-cineole caused significantly higher stress (P 0.001) to photosynthesis when compared to controls. Mitotic index data showed that 1,8-cineole severely decreased (P 0.001) all stages of mitosis when compared with controls, while 1,4-cineole only caused a decrease in the prophase stage (P 0.05). Although superficially similar in structure, these two cineoles appear to have different modes of action.
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Selected monoterpenes were tested for their ability to inhibit atmospheric methane consumption by three forest soils from different vegetation types and by the cultured methanotrophic strain, Methylosinus trichosporium OB3b. Subsurface soil from coniferous (Pinus banksiana), deciduous (Populus tremuloides), and mixed hardwood (Tsuga canadensis and Prunus pensylvanica) stands was used under field-moist (bulk and intact cores) and slurry conditions. Most of the hydrocarbon monoterpenes tested significantly inhibited (40–100%) methane consumption by soils at environmentally relevant levels, with (–)--pinene being the most effective. With the exception of -myrcene, monoterpenes also strongly inhibited methane oxidation by Methylosinus trichosporium OB3b. Carbon dioxide production was stimulated in all of the soils by the monoterpenes tested. In one case, methane production was stimulated by (–)--pinene in an intact, aerobic core. Oxide and alcohol monoterpenoids stimulated methane production. Thus, monoterpenes appear to be potentially important regulators of methane consumption and carbon metabolism in forest soils.