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Pseudomonas fluorescens enhances biomass yield and ajmalicine production in Catharanthus roseus under water deficit stress
Abstract
The effect of plant growth promoting rhizobacteria (PGPR) like Pseudomonas fluorescens on growth parameters and the production of ajmalicine were investigated in Catharanthus roseus under drought stress. The plants under pot culture were subjected to 10, 15 and 20 days interval drought (DID) stress and drought stress with Pseudomonas fluorescens at 1mgl(-1) and 1mgl(-1)Pseudomonas fluorescens alone from 30 days after planting (DAP) and regular irrigation was kept as control. The plants were uprooted on 41 DAS (10 DID), 46 DAS (15 DID) and 51 DAS (20 DID). Drought stress decreased the growth parameters and increased the ajmalicine content. But the treatment with Pseudomonas fluorescens enhanced the growth parameters under drought stress and partially ameliorated the drought induced growth inhibition by increasing the fresh and dry weights significantly. The ajmalicine content was again increased due to Pseudomonas fluorescens treatment to the drought stressed plants. From the results of this investigation, it can be concluded that, the seedling treatments of native PGPRs can be used as a good tool in the enhancement of biomass yield and alkaloid contents in medicinal plants, as it provides an eco-friendly approach and can be used as an agent in water deficit stress amelioration.
... According to some researchers, rhizosphere microorganisms act as biotic elicitors and can induce the synthesis of secondary products in plants [24]. Among these microorganisms, some have positive effects on plant growth promotion constituting the plant growth promoting rhizobacteria (PGPR) such as Azospirillum, Azotobacter, Pseudomonas fluorescens and several gram positive Bacillus sp [11]. These rhizobacterias induce the jasmonic acid and ethylene responses in plants [4,22]. ...
... It should be noted that the fluorescent strains of Pseudomonas and A. brasilense are both beneficial bacteria and have been mentioned in various sources as the most important and largest group of probiotic bacteria [1]. A review of the resources shows that the only effect of these bacteria on growth parameters and metabolite levels has been studied in C. roseus [11] while, in the present study, the effect of rhizobacteria on the expression of TIA biosynthetic pathway genes in C. roseus was evaluated for the first time. The purpose of this research is to investigate the individual and combined effect of two species of rhizobacteria as biotic treatment on the expression of some of the upstream and downstream TIA biosynthetic pathway genes, vinblastine and vincristine alkaloids content in roots of C. roseus. ...
... Some studies have shown that different types of probiotic bacteria have a positive effect on alkaloid content in the root of C. roseus. Jaleel et al. [11] studied the effect of P. fluorescens along with drought stress on vegetative traits, and ajmalicine content in roots of C. roseus plant. They suggested that ajmalicine content increased significantly due to exposure of drought-treated plants with P. fluorescens compared to non-treated plants and control under drought stress. ...
Background
Catharanthus roseus is the sole resource of vinblastine and vincristine, two TIAs of great interest for their powerful anticancer activities. Increasing the concentration of these alkaloids in various organs of the plant is one of the important goals in C. roseus breeding programs. Plant probiotic bacteria (PBB) act as biotic elicitors and can induce the synthesis of secondary products in plants. The purpose of this research is to study the effects of PBB on expression of the TIA biosynthetic pathway genes and the content of alkaloids in C. roseus.
Methods and results
The individual and combined effects of P. fluorescens strains 169 and A. brasilense strains Ab-101 was studied for expression of the TIA biosynthetic pathway genes (G10H, DAT, T16H and CrPRX) using qRT-PCR and the content of vinblastine and vincristine using HPLC method in roots of C. roseus. P. fluorescens. This drastically increased the content of vinblastine and vincristine alkaloids, compared to the control in the roots, to 174 and 589 (µg/g), respectively. Molecular analysis showed bacterium significantly increased the expression of more genes in the TIA biosynthetic pathway compared to the control. P. fluorescens increased the expression of the final gene of the biosynthetic pathway (CrPRX) 47.9 times compared to the control. Our findings indicate the correlation between transcriptional and metabolic outcomes. The same was true for A. brasilense.
Conclusions
It can be concluded that seed treatments and seedling root treatments composed of naturally occurring probiotic bacteria are likely to be widely applicable for inducing enhanced alkaloid contents in medicinal plants.
... Pseudomonas fluorescens enhances biomass yield and ajmalicine production in Catharanthus roseus under water deficit stress, as studied by Jaleel et al. (2007). Pseudomonas fluorescens enhanced the growth parameters under drought stress and partially ameliorated the drought-induced growth inhibition by increasing the fresh and dry weights. ...
... According to Jaleel et al. (2007) P. fluorescens enhances biomass yield and ajmalicine production in Catharanthus roseus under water deficit stress conditions. P. fluorescens enhanced the growth parameters under drought stress and partially ameliorated the drought-induced growth inhibition by increasing the fresh and dry weights. ...
... González-Caballo et al. (2022) and Ali et al. (2008) reported an increase in biological yield due to better nutrition of the plant's aerial organs and increased photosynthesis as a result of zinc sulfate application. On the other hand, Pseudomonas bacteria strains enhance plant growth and biological yield through mechanisms such as the production of plant hormones, dissolution of insoluble elements, and regulation of ethylene by producing siderophore and ethylene-regulating enzymes (Abdul Jaleel et al., 2007). Bacteria that promote plant root growth have the ability to secrete biologically active substances such as nicotinic acid, pantothenic acid, biotin, B vitamins, auxin, and gibberellin, which play a role in increasing root growth (Kader et al., 2002). ...
Mitigating drought stress is important for corn production. One way to alleviate drought stress and increase yield is to use supplementary Zn and Zn-solubilizing bacteria. The objective of this study was to investigate the effects of ZnSO 4 combined with rhizosphere bacteria on the yield, Zn uptake, relative water content (RWC), and water use efficiency (WUE) of corn under drought stress. A field experiment was conducted with sufficient irrigation, moderate stress, and the application of different combinations of ZnSO 4 and Zn-solubilizing bacteria. These combinations included four levels without Zn, with Zn applied to foliage, soil, or seed priming, and three levels of bacteria (without bacteria, Pseudomonas fluorescens, and P. aeruginosa). Drought stress decreased RWC by 11 %, the cobs/m 2 by 9 %, and increased WUE by 5.7 % in corn. However, priming or foliar application of ZnSO 4 with both P. fluorescens and P. aeruginosa strains increased the number of cobs/m 2 by 12.5 % and the number of rows/ cob by 15 %. Additionally, most methods of applying ZnSO 4 and bacteria increased the number of grains, 100-grain weight, grain yield, and WUE of corn. The results showed a 48 % and 52 % increase in 100-grain weight with the foliar application of ZnSO 4 and P. aeruginosa, respectively, under normal and drought conditions compared to the control. Soil application of ZnSO 4 without bacteria or foliar application of ZnSO 4 with P. aeruginosa enhanced grain and biological yield by 48 % and 8.9 % under drought stress, respectivly. Similarly, under sufficient irrigation, Zn seed priming with P. aeruginosa increased grain yield by 39.6 % and biological yield by 14.9 % compared with the control. Drought stress and foliar application of ZnSO 4 with P. fluorescens and P. aeruginosa increased the Zn content of corn leaves and grains. In conclusion, although drought decreased corn performance, foliar or priming of ZnSO 4 with Pseudomonas bacterial strains improved yield.
... The plants were uprooted on 90 DAP and separated the plants into root, stem and leaf analysis and antioxidant enzyme studied. GA 3 has a profound effect upon the antioxidant potentials in soil drenching and it caused a significant enhancement in the production of ajmalicine when compared to untreated control as well as sprayed plants [31]. ...
Catharanthus roseus (L.). G. Don. is become one of the important medical plants. This plant contains more than 100 alkaloids distributed in all parts of the plant, but in different proportions. The following aspects of Catharanthus are covered in this paper: diversity of alkaloids, phenolic compounds in Catharanthus roseus, role of different phytohormones in alkaloid improvement, diversity of microorganisms occurrence in C. roseus root exudates of C. roseus, role of PGPB interaction with root exudates, role of PGPB and AM fungi in improvement of alkaloid is discussed. Special attention has been paid in this to the effect of PGPB on plant biomass and alkaloid yield.
... Among different group of biofertilizers; nitrogen fixing and phosphorous solubilizing bacteria may be considered to be important since they improve plant nutrition. Plant Growth Prompting Rhizobacteria (PGPR) in the biofertilization of crops (Karlidag et al., 2007) has been a well known fact that these PGPR strains may promote growth either by fixation of atmospheric nitrogen or by solubilization, if minerals such as phosphorous (Karthikeyan et al., 2007;2008) and they can also promote growth production of plant growth regulators (Klopper and Schroth, 1978;Jaleel et al., 2007). ...
The effect of microbial consortium consisting plant growth promoting rhizobacteria (PGPR) like Azospirillum, Azotobacter, Pseudomonas and Bacillus were tested separately and in combination on Coleus forskohlii for pot culture experiment. The combinations of above mentioned PGPR strains significantly increased plant height, number of tubers, tuber length and tuber yield in Coleus forskohlii when compared to the uninoculated control. Plant growth promoting rhizobacteria (PGPR) exhibit direct and indirect mechanisms as plant growth promoters and biological control agents. Direct mechanism by PGPR, include the provision of bio-available phosphorus for plant uptake, nitrogen fixation for plant. The results of this study suggest that the PGPR applied in combination have yield of Coleus forskohlii.
... SOD is a major scavenger of superoxide dismutase anion radical (O 2-) that catalyses the dismulations of O 2-with great efficiency resulting in the production of H 2 O 2 and O 2 . The H 2 O 2 scavenging system represented by APX and CAT are the most important in imparting tolerance than sod in oxidative stressed plants (Jaleel et al., 2007). Sakthivel (2012) reported that the PGPR consortium treatment increased the antioxidant enzyme activity such as Superoxide dismutase (SOD), Peroxidase (POX) and Catalase (CAT) in Coleus forskohlii. ...
... Numerous studies have shown that in both greenhouse and field experiments, different species of Pseudomonas can improve root biomass, plant growth, and crop yield. Studies on crops such as turmeric (Jaleel et al. 2007), wheat (Garc� ıa-Seco et al. 2013;Jain and Pandey 2016), mustard (Hou and Oluranti 2013), opium poppy (Sharma, Shankhdhar, and Shankhdhar 2013), marigold , rape and fescue grass (Grobelak, Napora, and Kacprzak 2015), and blackberries (Kumar et al. 2016) have demonstrated that root and leaf inoculation with P. fluorescens can significantly increase plant height by a range of 12.2-37.5%. Afzal et al. (2012), Garc� ıa-Seco et al. (2013), Yasmin, Hafeez, and Rasul (2014), Li et al. (2017), andSingh et al. (2021) demonstrated that Pseudomonas species, such as P. koreensis, P. aeruginosa, and P. fluorescens, not only produced significantly greater shoot and root biomass than an uninoculated control but also improved plant growth across a variety of crops, including wheat, sugarcane, tobacco, bird foot trefoil, Italian ryegrass, and cotton. ...
Pseudomonas species are a versatile group of gram-negative bacteria that thrive in diverse ecological niches including soil, water, and plant environments. Their remarkable metabolic flexibility arises from their ability to utilize a plethora of compounds as carbon or energy sources, a feature that has attracted extensive scientific research. These microbial powerhouses are equipped to degrade various pollutants and toxins, thereby positioning them as valuable allies for bioremediation. This detoxification process is not only claim for ecological fame. Pseudomonas also exhibits potent biocontrol capabilities, and acts as a guard against plant pathogens. Their control strategies includes a suite of antimicrobial substances, along with an innate ability to outcompete other microbes for nutrients and stimulate plant defense. By harnessing these natural defenders, a range of Pseudomonas-based biocontrol agents have been formulated for agriculture. This approach is of growing interest for leveraging Pseudomonas strains as biofertilizers to support sustainable farming practices. These bacterial promoters enhance plant growth by boosting nutrient assimilation and by promoting robust root systems. New-generation biofertilizers can support crop yields and fortify soil vitality, thereby offering resilience to abiotic stress. This offers dual benefit of improving agricultural productivity while attenuating the harmful environmental problems caused by chemical fertilizers. Overall, the versatility of Pseudomonas species makes them a promising resource, spanning from agricultural enhancement to environmental remediation. As research accelerates, the ambition is to unlock and refine the myriad applications of these extraordinary bacteria.
... We found higher bacoside-A in plants inoculated with either Gm alone or in consortia with Pt. The improvement of secondary metabolites content of medicinal plants by inoculating plant-associated microbes in Artemesia annua [11,45] Catharanthus roseus, Bacopa monnieri etc. [46][47][48] has been noticed earlier by many researchers. Higher shoot biomass may be coupled with increased bacoside-A content and yields. ...
The present study aimed to evaluate the performance of Indole-3-acetic acid-producing bacteria (IPB) and arbuscular mycorrhizal fungi (AMF) in compatible form for early establishment and higher growth, yield, and secondary metabolite content of vegetatively propagated Bacopa monnieri plants. Four species of Glomus, viz., G. mosseae (Gm), G. aggregatum (Ga), G. fasciculatum (Gf), G. intraradices (Gi), and two Indole-3-acetic acid-producing bacteria (IPB), Bacillus mojavensis (Bm), and Pantoea sp. (Pt) were evaluated individually and in combinations in a pot experiment. Various plant growth parameters like height, biomass, NPK uptake, mycorrhizal colonization, bacterial population in the rhizosphere, phos-phatase activity, and bacoside-A content were determined and found to vary with different treatments. Among all the treatments, plants inoculated with Gm + Pt performed better than any other treatment or un-inoculated control. The performance of the consortium of Gm + Pt was further validated in a field experiment on the same parameters. A clear synergistic interaction between Gm and Pt was observed as Pt enhanced rooting and subsequently improved the colonization and spore population of Gm. On the other hand, the presence of Gm improved the population of Pt in the rhizosphere. The presence of both microbes improved the bacoside-A yields in B. monnieri. The results of this experiment indicate the compatibility and synergy between G. mosseae and Pantoea sp. and suggest using this microbial consortium for plant propagation and growth enhancement while improving soil biological health.
... Azotobacter chroococcum improved vegetative growth (especially root mass) and seed yield of three cultivars of Triticum beautivum(Kumar et al., 2001). Application of Pseudomonas fluorescens biofertilizer under drought stress on Catharanthus roseus could reduce the effect of drought and increase vegetative parameters such as the fresh and dry weight of the plant(Jaleel et al., 2007). Use of Azotobacter chroococcum and Glomus mosseae produced the highest growth, seedling establishment, plant height, and fruit yield of Punic agranatum(Aseri et al., 2008).According to the results of Adesemoye et al.(2009), biofertilizers of Bacillus pumilus T4, Bacillus amyloliquefaciens IN937a, and Rhizophagus irregularis greatly increased the yield and growth of Solanum lycopersicum. ...
Chemical fertilizers have a devastating impact on soil and the environment when used in seedling production and planting. Conversely, biofertilizers can enhance soil structure and fertility while mitigating the harmful effects of chemical fertilizers on the environment. This study aimed to identify an appropriate biofertilizer for Zygophyllum eurypterum, a species that is particularly amenable to arid area restoration. To this end, we conducted an experiments using six different biofertilizer treatments (Azotobacter chroococcum, Azospirillum lipoferum, Flavobacterium F-40, Bacillus megaterium, Pseudomonas fluorescens, and Rhizophagus irregularis) and fertilizer-free control in a completely randomized design by cultivation of the plants in the seedling bags with 15 replications. This was done in the spring of 2018, in the research farm of Semnan University. Vegetative growth parameters such as root length, fresh and dry weight of roots and shoots, number of leaves, shoot diameter, and total chlorophyll were measured three months after planting. The percentage of root colonization with mycorrhizal fungi was measured at three and six months of age of seedlings. In this context, the maximum length of root (33.40 cm) and shoot (18.20 cm), height (51.30 cm), weight of root (99.94 g) and shoot (473.90 g), number of leaves (58.00), shoot diameter (3.32 mm) and total chlorophyll (74.96) were observed in the treatment by Pseudomonas fluorescens. Symbiotic mycorrhizal fungi was confirmed and it increased root length and plant height. The percentage of root colonization increased over time. Root to shoot ratio was increased by application of Azospirillum lipoferum fertilizer. The results showed that the use of biofertilizers Pseudomonas fluorescens, Azospirillum lipoferum, and Rhizophagus irregularis can be recommended in the production of Zygophyllum eurypterum seedlings.
... These developments further underscore the urgent need for the formulation of an effective inoculum for the plant and the significance of this study. Studies attempting to alleviate the effects of abiotic stress on plants often take place in field conditions [28] or make use of matured plants [29]. In cases where they are conducted in sterile environments, similar results are evident where shoot biomass for the negative control is significantly lower than the treated plants [12]. ...
Lessertia frutescens is a multipurpose medicinal plant indigenous to South Africa that is used for the management of cancer, stomach ulcers, wounds, etc. The use and demand for the raw materials from this plant have been increasing steadily over the years, putting strain on the dwindling wild populations. Although cultivation may provide relief to the strained supply, the persistent drought climate poses a threat to the plant’s growth and productivity. This study explored three plant-growth-promoting rhizobacteria isolates, TUTLFNC33, TUTLFNC37 and TUTLFWC74, obtained from the root nodules of Lessertia frutescens as potential bioinoculants that can improve yield, biological activities and the production of secondary metabolites in the host plant. Isolate TUTLFNC37 was identified as the most promising isolate for inoculation of Lessertia frutescens under drought conditions as it induced drought tolerance through enhanced root proliferation, osmolyte proline accumulation and stomatal closure. Superior biomass yield, phenolics, triterpenes and antioxidant activity were evident in the extracts of Lessertia frutescens inoculated with TUTLFNC37 and under different levels of drought. Furthermore, the metabolomics of the plant extracts demonstrated the ability of the isolate to withstand drastic changes in the composition of unique metabolites, sutherlandiosides A–D and sutherlandins A–D. Molecular families which were never reported in the plant (peptides and glycerolipids) were detected and annotated in the molecular networks. Although drought had deleterious effects on Lessertia frutescens, isolate TUTLFNC37 alleviated the impact of the stress. Isolate TUTLFNC37 is therefore the most promising, environmentally friendly alternative to harmful chemicals such as nitrate-based fertilizers. The isolate should be studied to establish its field performance, cross infectivity with other medicinal plants and competition with inherent soil microbes.
... In the present study, the P. fluorescens isolate Pfl reduced the intensity of sheath blight in rice. Jaleel et al. (2007) had indicated that P. fluorescens serves as a strong elicitor of plant defense reactions. Studies have suggested that the preapplication of fluorescent Pseudomonas toughens host cell wall structure, thereby restricting pathogen invasion into plant tissues (Preston 2004). ...
Rice (Oryza sativa L.) plant is vulnerable to a number of pest and diseases. Among them sheath blight disease caused by Rhizoctonia solani, insect pest and brown plant hopper (BPH) (Nilapavata lugens) are the most devastating agents and major challenge to rice cultivation. Plant growth-promoting rhizobacteria (PGPR) are associated with plant roots which augment plant productivity and immunity. Protein analysis was carried out to study the molecular mechanisms underlying PGPR mediated pest and disease resistance and growth promotion. Plants were treated with and without Pseudomonas fluorescens strain Pf1 and challenged with pest and pathogen at 0, 6, 24, 48, 72, and 96 h after inoculation. The comparative analysis of relative abundances of protein bands between inoculated and non-inoculated samples was carried out. Five proteins were upregulated and 15 were differentially regulated in PGPR-primed plants challenged with BPH. In PGPR-primed plants challenged with pathogen, 27 proteins were upregulated. The differential protein bands were sequenced by Matrix Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS). Protein sequencing results showed high-percent homology with chloroplastic aldolase, fructose-bisphosphate aldolase, peroxidase, 2-cys peroxiredoxin bas1, chloroplastic-like, small subunit of ribulose-1,5-bisphosphate carboxylase, Os12g0291400 and hypothetical protein OsI_38046. Western blotting detected the presence of PR protein chitinase. The analysis confirmed the presence of chitinase of molecular weight 17, 20, and 35 kDa in PGPR primed plant challenged with R. solani. These results showed that the differentially expressed proteins possibly play role in biotic stress defense in plants challenged with biotic stress. Expression proteins remarkably influenced by Pf1 colonization, which might be a key element for induced systemic tolerance by PGPR.
... Increased IAA production, fresh and dry weights [66] Micrococcaceae strain HW-2 ...
Climate change has exacerbated the effects of abiotic stresses on plant growth and productivity. Drought is one of the most important abiotic stress factors that interfere with plant growth and development. Plant selection and breeding as well as genetic engineering methods used to improve crop drought tolerance are expensive and time consuming. Plants use a myriad of adaptative mechanisms to cope with the adverse effects of drought stress including the association with beneficial microorganisms such as plant growth promoting rhizobacteria (PGPR). Inoculation of plant roots with different PGPR species has been shown to promote drought tolerance through a variety of interconnected physiological, biochemical, molecular, nutritional, metabolic, and cellular processes, which include enhanced plant growth, root elongation, phytohormone production or inhibition, and production of volatile organic compounds. Therefore, plant colonization by PGPR is an eco-friendly agricultural method to improve plant growth and productivity. Notably, the processes regulated and enhanced by PGPR can promote plant growth as well as enhance drought tolerance. This review addresses the current knowledge on how drought stress affects plant growth and development and describes how PGPR can trigger plant drought stress responses at the physiological, morphological, and molecular levels.
... The stimulatory effects of these PGPR strains on the yield and growth of these crops were attributed to the ability to fix nitrogen, phytohormone synthesis, and mineral solubilization (Cakmakci et al., 2007;Karlidag et al., 2007;Kevin Vessey, 2003). For C. roseus, P. fluorescens is known to enhance biomass yield and ajmalicine alkaloid content under waterdeficient stress (Jaleel et al., 2007). The higher N, P, and K content in PGPR combination treatment may have resulted from the nitrogen fixation and P-solubilizing ability of these strains. ...
... Studies suggest that the reduction in plant growth might be an outcome of plant's adaptive response. Under stress conditions, plants conserve their energy before inducing defense responses to prevent permanent damage (Jaleel et al., 2007). Similar to growth patterns of neem roots, Jing-Yan and Zhao-Pu (2010) also reported that plant growth reduces with the increase of stress duration. ...
... Osmoprotectants are made up of various inorganic ions and organic solutes that act on the cellular osmotic potential and increase water use efficiency [49]. The accumulation of proline is already recognized as an important indicator of abiotic stress in plants, favoring intracellular homeostasis [50] and proving to be capable of increasing the capacity of plants to overcome lower water potentials, since this osmolyte has a particularity of buffering under the effect of water scarcity [51,52]. ...
A strategy using bacilli was adopted aiming to investigate the mitigation of the effects of water deficit in sesame. An experiment was carried out in a greenhouse with 2 sesame cultivars (BRS Seda and BRS Anahí) and 4 inoculants (pant001, ESA 13, ESA 402, and ESA 441). On the 30th day of the cycle, irrigation was suspended for eight days, and the plants were subjected to physiological analysis using an infrared gas analyzer (IRGA). On the 8th day of water suspension, leaves were collected for analysis: superoxide dismutase, catalase, ascorbate peroxidase, proline, nitrogen, chlorophyll, and carotenoids. At the end of the crop cycle, data on biomass and vegetative growth characteristics were collected. Data were submitted for variance analysis and comparison of means by the Tukey and Shapiro–Wilk tests. A positive effect of inoculants was observed for all characteristics evaluated, contributing to improvements in plant physiology, induction of biochemical responses, vegetative development, and productivity. ESA 13 established better interaction with the BRS Anahí cultivar and ESA 402 with BRS Seda, with an increase of 49% and 34%, respectively, for the mass of one thousand seeds. Thus, biological indicators are identified regarding the potential of inoculants for application in sesame cultivation.
... Free proline increased exponentially with the increase in NaCl levels in S. Nigrum [8]. The NaCl stress enhanced the total alkaloid content in S. nigrum [9,8]. The effect of salt stress on S. melongena has been reported by few researchers [8,10]. ...
In the present study, the leaf explant cultured on a MS medium supplemented with BAP (4.44 µM) + NAA (0.98 µM) had the ability to induce more amount of green and friable callus. The 40 days old best grown callus was sub cultured on the combination of various concentrations of BAP (2.22, 4.44, 6.66, 8.88 and 11.1µM) along with same concentrations of NAA (0.98 µM) with different concentrations of NaCl (20, 40, 60, 80 and 100 mM). The highest percentage of callus was observed on MS + BAP (4.44 µM) + NAA (0.98 µM) + NaCl 20 mM with the percentage of 62.33±1.35. The shoot induction was observed on the same media composition with 95% Original Research Article Vanitha et al.; BJPR, 14(6): 1-11, 2016; Article no.BJPR.30425 2 response. Preliminary phytochemical analysis of ethanol and methanol extracts of salt callus showed the presence of alkaloids, saponins, steroids, tannins/ phenolics, flavonoids, glycosides and reducing sugar. GCMS analysis revealed the presence of 27 compounds in the ethanolic extract of S. melongena. Among that there are seven major peaks which indicating the presence of seven major phytochemical constituents. From the twenty seven compounds identified, the most prevailing compounds were, Tetracontane (12.64%), Lupeol (12.44%), N-Tetratetracontane (11.60%), Tetrapentacontane (11.05%) Dotriacontane (10.90%), n-Hexatriacontane (9.18%) and Eicosane (5.26%). Twenty five compounds were identified through GCMS analysis of methanolic salt callus extracts of S. melongena. The most prevailing compounds were 1-Heptacosanol (54.39%), Ergosta-5, 7, 22-trien-3-ol (8.37%), Tetracosane (5.26%), Tetratetracontane (4.49%) and Beta Carotene (4.25%).
... For example earlier studies have determined seed germination response of Limonium stocksii (Hameed et al., 2014), Linum usitatissimum (Moghaddam et al., 2018), Gypsophila oblanceolata (Sekmen et al., 2012), Basil (Zahedi et al., 2011), and sunflower (Kaya et al., 2019) to different salinity levels. Seedling development is also suppressed and delayed under salinity stress (Jaleel et al., 2007). ...
Plants respond differently to salt stress depending on their genetic structure and the severity of the stress. Salinity reduces seed germination, delays plant emergence, and inhibits seedling growth. The selection of the tolerant genotypes, however, plays a vital role in increasing agricultural output since various genotypes greatly vary for their tolerance to salinity. Therefore, this study determined the impact of five different NaCl levels (i.e., 0, 50, 100, 150 and 200 mM) on seed germination and growth attributes of 10 flax (Linum usitatissimum L.) genotypes. The germination and growth characteristics of the genotypes under study were examined using the biplot approach at varied salt levels. The results indicated that individual and interactive effects of genotypes and salinity levels significantly (p ≤ 0.01 or p ≤ 0.05) affected several seed germination traits. The relations of genotype × germination traits indicated that 'G4' and 'G6' were the most stable genotypes with the highest performance regarding seed germination characteristics. The genotype 'G2' was associated with shoot length, while 'G7' was linked with salinity tolerance index. The biplot divided the germination characteristics into five different groups according to sector analysis. Most of the germination parameters had higher values under 100 mM, while some of the parameters had better values under 0, 50 and 200 mM NaCl levels. The tested genotypes varied for their seed germination and growth response depending on the NaCl levels. The genotypes 'G4', 'G5' and 'G6' proved more tolerant to high NaCl levels. Therefore, these genotypes can be used to improve flax productivity under saline soils.
... 52,53 Some pharmacological research on F. subpinnata has been reported, revealing that its essential oil has anti-cancer activity, 52,54 as well as antioxidant, 53 and antibacterial activities. 52,54 Hyssopus officinalis L. is one of the most important plants from the Lamiaceae family, being considered a medicinal plant and cultivated in regions of Asia, Europe and America. The aerial parts of H. officinalis have been traditionally used in the treatment of infections due to its antiseptic properties. ...
"Medicinal plants have played an important role in the development of human health care and culture, serving as both medicine and food. Herbal drugs have been used for centuries for the treatment of several diseases and many of the new medicines are produced based on recent research on their traditional uses. Medicinal plants of the Middle East are regarded as a rich resource of different valuable bioactive compounds. Such compounds extracted from natural resources maintain many potential health benefits. The application of bioactive compounds is, however, rather limited in food and drug formulations because of their poor bioavailability, fast release and low solubility. Thus, encapsulation can protect the bioactive compounds from environmental stress, improve their physicochemical functionalities, reduce the potent toxicity of drugs, modify the release of encapsulated active materials, reduce dosage, enhance their health-promoting and anti-disease activities. This review discusses the importance of the pharmaceutical properties of thirty-two species of relevant medicinal plants native to the Middle East and their uses in various industrial applications. "
... observed that Pseudomonas aeruginosa supports the growth of Vigna radiate plants under drought stress conditions. Likewise, P. fluorescens improved the growth of Catharanthus roseus by secreting ajmaline under drought stress(Jaleel et al., 2007). Bacillus subtilis, Ochrobactrum pseudogrignonense and Pseudomonas sp. ...
... Coronatine enhances water transport by stimulating AQP Osmotic stress has a profound impact on ecological and agricultural systems (Jaleel et al., 2007). Improving water uptake capacity is crucial for osmotic stress tolerance in plants. ...
Water uptake is crucial for crop growth and development and drought stress tolerance. The water channel aquaporins (AQP) play important roles in plant water uptake. Here, we discovered that a jasmonic acid analog, coronatine (COR), enhanced maize (Zea mays) root water uptake capacity under artificial water deficiency conditions. COR treatment induced the expression of the AQP gene Plasma membrane intrinsic protein 2;5 (ZmPIP2;5). In vivo and in vitro experiments indicated that COR also directly acts on ZmPIP2;5 to improve water uptake in maize and Xenopus oocytes. The leaf water potential and hydraulic conductivity of roots growing under hyperosmotic conditions were higher in ZmPIP2;5‐overexpression lines and lower in the zmpip2;5 knockout mutant, compared to wild‐type plants. Based on a comparison between ZmPIP2;5 and other PIP2s, we predicted that COR may bind to the functional site in loop E of ZmPIP2;5. We confirmed this prediction by surface plasmon resonance technology and a microscale thermophoresis assay, and showed that deleting the binding motif greatly reduced COR binding. We identified the N241 residue as the COR‐specific binding site, which may activate the channel of the AQP tetramer and increase water transport activity, which may facilitate water uptake under hyperosmotic stress.
... Meanwhile, del Amor et al. (2008) found that Capsicum annuum (sweet pepper) inoculated with a mixture of Azospirillum brasilense and Pantoea dispersa had higher levels of total phenolics in green fruits, but as these ripened, the difference between treatments became non-significant. PGPR can also increase the concentration of alkaloids in foliar tissues, as Jaleel et al. (2007) found that ajmalicine levels were higher in plants of Catharanthus roseus (Madagascar periwinkle) when inoculated with P. fluorescens. ...
Plant secondary metabolites (PSMs) such as terpenes and phenolic compounds are known to have numerous ecological roles, notably in defence against herbivores, pathogens and abiotic stresses and in interactions with competitors and mutualists. This book reviews recent developments in the field to provide a synthesis of the function, ecology and evolution of PSMs, revealing our increased awareness of their integrative role in connecting natural systems. It emphasises the multiple roles of secondary metabolites in mediating the interactions between organisms and their environment at a range of scales of ecological organisation, demonstrating how genes encoding for PSM biosynthetic enzymes can have effects from the cellular scale within individual plants all the way to global environmental processes. A range of recent methodological advances, including molecular, transgenic and metabolomic techniques, are illustrated and promising directions for future studies are identified, making this a valuable reference for researchers and graduate students in the field.
... According to Gill and Tuteja (2010), different signals from both abiotic and biotic stresses could act as elicitors for plant cells, and confer tolerance to stress. Several abiotic elicitors have been tested for drought stress tolerance like alginate-derived oligosaccharides (Liu et al. 2009), ketoconazole (Abdul et al. 2007), 2-aminoethanol (Mascher et al. 2005), abscisic acid (ABA) (Lu et al. 2009), rhizobia (Romdhane et al. 2009;Franzini et al. 2010), endophytic fungus (Sun et al. 2010;Kane et al. 2011), and phyto-stimulating rhizobacterium (Va'zquez et al. 2001;Mayak et al. 2004;Arshad et al. 2008;Yang et al. 2009;Benabdellah et al. 2011;Timmusk and Nevo 2011;Lim and Kim 2013;Timmusk et al. 2014). These elicitors can maintain drought stress tolerance indicators; prevent the accumulation of reactive oxygen species (ROS); increase activities of antioxidant enzymes; and maintain biomass, crop yields, and relative water content (Wang et al., 2012a, b;Mullan and Pietragalla 2012;Kakar et al. 2016;Vimal et al. 2017). ...
The present study is conducted for the growth and yield improvement of tomato plants under drought stress by inoculation of hexa plant growth-promoting microorganisms (PGPM). Hexa-PGPM consortium (Bacillus megaterium, Pseudomonas fluorescens, P. aeruginosa, P. putida, Paenibacillus polymyxa, and Trichoderma harzianum) is inoculated to the tomato plant, and growth attributes, membrane integrity, water status, accumulation of osmolyte, reactive oxygen species (ROS) scavenging capability, and the qRT-PCR analysis were performed for expression of stress-responsive DREB, APX, CAT, SOD, and P5CS under 80% and 40% moisture content of the field capacity. Soil physico-chemical and microbial properties were also evaluated. Our results revealed that under drought, hexa-PGPM consortium-inoculated plants exhibited lower cellular damage and better plant growth and yield than non-inoculated plants. Antioxidant enzyme catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX) activity decreases under drought stress condition and it increases in hexa-PGPM-inoculated plants. Simultaneously, the gene expression analysis showed up-regulation of a transcriptional activator (DREB1), osmolyte accumulators (P5CS), and ROS scavengers (CAT, SOD, APX) gene by application of hexa-PGPM consortium. Overall, the results showed that the hexa-PGPM application confers drought mitigation in tomatoes by altering different physico-biochemical and molecular parameters. In addition, the PGPM application also improved the soil’s physical, chemico-chemical, and biological properties under drought stress conditions. The present study supports the application of hexa- PGPM consortium to elevate drought tolerance, yield, and soil fertility enhancement under drought stress as a low-cost agro-biotechnology tool and environment-friendly drought management techniques in tomato crops.
... Further studies have demonstrated the beneficial and synergistic effects of dual PGPR and AMF inoculation on MAPs under metal, water, and salt-stressed conditions [259][260][261][262][263]. It has been demonstrated under conditions of water stress that the combined inoculation of myrtle (Myrtus communis L.) with AMF (R. irregularis) and PGPR (Pseudomonas fluorescens, P. putida) species improved hydromineral supply and EO production as well as enhancing plants' oxidative defense [262]. Furthermore, it was reported that combined inoculation of PGPR and AMF improved plant growth, metabolite content, and root length under drought stress in various MAPs [264,265]. Similarly, co-inoculation with plant-growth-promoting fungi (like Trichoderma spp. and AMF) and PGPR has been reported to increase the production of secondary metabolites and hairy roots of Chinese salvia (Salvia miltiorrhiza) under conditions of drought or salinity stress [261]. ...
Medicinal and aromatic plants (MAPs) have been used worldwide for thousands of years and play a critical role in traditional medicines, cosmetics, and food industries. In recent years, the cultivation of MAPs has become of great interest worldwide due to the increased demand for natural products, in particular essential oils (EOs). Climate change has exacerbated the effects of abiotic stresses on the growth, productivity, and quality of MAPs. Hence, there is a need for eco-friendly agricultural strategies to enhance plant growth and productivity. Among the adaptive strategies used by MAPs to cope with the adverse effects of abiotic stresses including water stress, salinity, pollution, etc., their association with beneficial microorganisms such as arbuscular mycorrhizal fungi (AMF) can improve MAPs’ tolerance to these stresses. The current review (1) summarizes the effect of major abiotic stresses on MAPs’ growth and yield, and the composition of EOs distilled from MAP species; (2) reports the mechanisms through which AMF root colonization can trigger the response of MAPs to abiotic stresses at morphological, physiological, and molecular levels; (3) discusses the contribution and synergistic effects of AMF and other amendments (e.g., plant growth-promoting bacteria, organic or inorganic amendments) on MAPs’ growth and yield, and the composition of distilled EOs in stressed environments. In conclusion, several perspectives are suggested to promote future investigations.
... 35 Phytochemical variations have also been observed to occur in Salvia officinalis inoculated with different rhizobacteria. 36 Endophytic Pseudomonas fluorescens has been shown to promote the growth and accumulation of both volatile oils and sesquiterpenes in Atractylodes lance. 14,37 A study found that the resident endophytes might alter the content of Bletilla striata polysaccharide (BSP). ...
An endophytic Pseudomonas fluorescens (BsEB-1) was obtained from the roots of Bletilla striata. We investigated its growth-promoting properties and observed the impact of its inoculation on both the growth and polysaccharide content of Bletilla striata tubers. It was found that BsEB-1 possessed three growth-promoting activities: phosphate-solubilizing, produced indoleacetic acid (IAA) and siderophores, but had no nitrogen-fixing activity. BsEB-1 could rapidly attach to the root hairs of Bletilla striata tissue culture seedlings and endophytically colonize the region of maturation in the roots. It also significantly promoted the rooting and transplant survival rate of the seedlings, as well as the growth and expansion of the tubers, but did not increase their polysaccharide content. Pseudomonas fluorescens BsEB-1 exhibits potential for applications in the artificial planting of Bletilla striata.
Description of the subject: Durum wheat (Triticum durum Dsf.) is a species widely cultivated in Algeria and throughout the world. This crop is subject to unfavourable climatic conditions, causing significant water stress which is often a major constraint to its growth and improvement. Objective : This work aims to study the morphological and biochemical responses of three genotypes of this species inoculated by four bacterial strains.
Methods : The study was carried out according to a split-split-plot design with three replicates for a total of 54 trials each pot contains four plants. The trials were conducted in greenhouses. The first inoculation treatment was Frankia sp strain CcI3 and the second treatment was a combination of three strains (Azospirillum brasilense, Bacillus sp. and Pseudomonas sp.) to severe water stress applied for 10 days.
Results : The results show that water stress has a depressing effect on the length and dry weight of the aerial part while the length and dry weight of the roots tends to increase. Stress influences the total chlorophyll and relative water content negatively; however, it increases the levels of total soluble protein and antioxidant enzymes. The Boussellem genotype appears to be more tolerant to stress than the other two genotypes Waha and Cirta. Bacterial inoculation revealed slight significant effects on morphological traits (length and dry weight of the root and aerial parts), physiological traits (total chlorophyll content and relative water content) and strong significant effects on biochemical traits such as the content of total soluble proteins and antioxidant enzymes (Catalase and Ascorbate peroxidase) compared to the control in all three genotypes
Conclusion : Indeed, the inoculation of plants by PGPBs (Plant Growth-Promoting Rhizobacteria) presents an alternative to improve the drought tolerance mechanisms that durum wheat faces.
Online url: https://asjp.cerist.dz/en/article/209928
Drought stress is a critical environmental factor affecting sugarcane yield, and the adaptability of the sugarcane rhizosphere bacterial community is essential for drought tolerance. This review examines the adaptive responses of sugarcane rhizosphere bacterial communities to water stress and explores their significant role in enhancing sugarcane drought tolerance. Under drought conditions, the sugarcane rhizosphere bacterial community undergoes structural and functional shifts, particularly the enrichment of beneficial bacteria, including Streptomycetales and Rhizobiales. These bacteria enhance sugarcane resilience to drought through various means, including nutrient acquisition and phytohormone synthesis. Furthermore, changes in the rhizosphere bacterial community were closely associated with the composition and levels of soil metabolites, which significantly influenced the physiological and biochemical processes of sugarcane during drought stress. This study deepens our understanding of rhizosphere bacterial communities and their interactions with sugarcane, laying a scientific foundation for developing drought-resistant sugarcane varieties, optimizing agricultural practices, and opening new avenues for agricultural applications.
The Nutritional requirements of trees have received less attention compared to agricultural crops. Tree species provide a long-term investment for many potential benefits for human well-being. Nutritional supplementation is a requisite for improvement in the growth and quality of planting stock. Biofertilizers are a boon for chemical fertilizers, which produce several environmental hurdles. Certain groups of bacteria and fungi are majorly used as biofertilizers in tree cultivation. It is a sustainable approach to support growth in these higher plants. Heavy reliance on the indiscriminate use of chemical fertilizers results in adverse effects on the soil ecosystem, environmental quality, and human and animal health risks. The practice of inorganic fertilizers can be greatly reduced by substituting them with eco-friendly microbial biofertilizers or bio-inoculants. Plant Growth-Promoting Rhizobacteria (PGPR) and mycorrhizal fungi are frequently involved in biofertilizer formulations, providing plants with nutrients required to enhance their growth, increase yield, manage abiotic and biotic stress, and prevent phytopathogens attacks. Being an alternate natural source of nutrients, biofertilizers help sustain soil health, fertility, and productivity while significantly improving the growth of plants. In addition, these microbial inoculants are organic, sustainable, and environmentally friendly, thereby reducing the ill effects on human health and the soil biome. Thus, bio-inoculants form an attractive and pecuniary approach towards the development of sustainable forestry. The availability of pertinent microbial strains can increase the survival as well as the quality of seedlings and other propagation units. Hence, the chapter aims to encompass the importance, roles, and application of biofertilizers in improving tree nutrition.
Salinity is an environmental factor that adversely impacts seed germination, growth, and productivity by causing osmotic and ionic imbalances in plants. Expansins, which are non-enzymatic proteins, play important role in response to abiotic stress. In this study, three transgenic lines of Nicotiana tabacum cultivar. Samsun overexpressing AtEXPA1 were investigated for physiological and biochemical traits at four different NaCl concentration: 0, 100, 200, and 300 mM. The study was designed based on a factorial experiment in a completely randomized design with four replications. The results indicated that higher levels of salinity stress reduced relative water content and chlorophyll content in leaf, while increasing the electrolyte leakage index, malondialdehyde, and proline content. Lines 4 and 2 exhibited higher Na+ and K+ content, as well as an improved K+/Na+ ratio in the leaves, compared to line 7 and the non-transgenic wild-type plants. Enzymatic antioxidants, such as catalase, ascorbate peroxidase, and polyphenol oxidase, demonstrated high activity, especially in lines 4 and 2 under 200 mM salinity. However, guaiacol peroxidase activity did not significantly differ between wild-type and transgenic lines under severe salt stress. Principal component analysis and clustering identified lines 4 and 2 as salt-tolerant, while line 7 was non-tolerant. These findings suggest that lines 4 and 2 hold promise for use in advanced plant breeding programs aimed at improving salinity tolerance.
Rapidlyincreasing population, the demand for food has increased substantially. To overcome food deficits, an increase in agricultural production is needed, and for sustainability, the qualities of crops as well as maintaining the fertility of the soil are challenging situations. Soil contains limited amount of macro, micronutrients and innumerable amounts of soil microflora, which helps in crop production. Since the mid-19th century, a plethora of chemical fertilizers have been extensively used to improve crop production, but over time, they have shown disastrous effects on the soil compositionand profile. In the current alarming scenario, a new technology arearising, namely nanotechnology, in the field of agriculture. Nano-chemicals can play a paramount role in sustainable agriculture. This reviewsummarizes a variety of nanomaterials as pesticide, fertilizers and control of attack of fungus and bacterial diseases. Here discussed a range of nanomaterials including Ag, Fe, Cu, Si, Se, Al, Zn, ZnO, TiO2 and carbon nanotubes non-propitious effectsof biomagnification. This review alsodiscussesthe several mechanisms which show how nanomaterials does work as nanofertilizer, nano pesticides, and control bacterial and fungal diseases along with the advantages and disadvantages in the sustainable approach of agriculture. Furthermore, it discusses the synergistic effect of nanomaterials and conventional approach involved in agriculture practices. Nano-fertilizers and nano-biofertilizers are new tools that have evolved for the sustainableagricultural and food security.
Plants are an essential component of our daily diet, and their nutritional value has been thoroughly studied for many years. The ability of plants to adapt to changing environmental conditions through signaling systems is an essential component of their survival. Plants undergo an array of physiological alterations to respond to stress from biotic sources. Secondary compounds frequently accumulate in crops that are sensitive to stress, particularly those with several eliciting agents or signaling molecules. Plants contain various types of bioactive compounds, including phytosterols, alkaloids, glycosides, and polyphenols, which make them valuable for the food and pharmaceutical industries. The increased production of secondary metabolites via elicitation has opened up a new field of study with the potential to provide substantial financial gains for the pharmaceutical and nutraceutical industries. These elicitors are pharmacological compounds that activate specific transcription factors and up-regulate genes to activate metabolic pathways. Thus, the current review discusses the mechanism of biotic elicitation and various elicitation techniques using biotic (proteins, carbohydrates, rhizobacteria, fungi, and hormones) elicitors that may increase the yield of secondary metabolites, particularly in medicinal plants, which is advantageous to the agrochemical and therapeutic industries.
Present work was conducted to evaluate the effect of NaCl stress on morpho-agronomic and biochemical responses of some desert grass species of Cholistan i.e. Cenchrus ciliaris, Cynodon dactylon, Cymbopogon jwarancusa, Lasiurus scindicus and Panicum antidotale. Populations of all these five grasses were taken from the RD-65 which was selected site of Cholistan desert of Pakistan. The stumps of mature plants of each species of grass were grown in the pots for the period of three months. Research work was completely in randomized design (CRD); two factors (salt levels and species) with 5 replicas of each treatment. Treatments were named as; T0 (0 mM), T1 (100 mM), T2 (200 mM) and T3 (300 mM) of NaCl levels applied were three after the intervals of seven days. Morpho-agronomic characters were noted after the completion of experiment. It was proposed that all the selected species are the halophytic grasses which were also native to the harsh climates and have some of the potential against NaCl stress. Generally, NaCl negatively affected the agro-morphic characters of Cenchrus ciliaris, Cynodon dactylon, Lasiurus scindicus and Panicum antidotale from moderate levels of salinity to higher levels of salinity 300 mM except the Cymbopogon jwarancusa where most of the characteristics showed positive effects from the salt levels of 0 mM to 300 mM. Some water-soluble phytochemicals like sugars, saponins and protein were mostly detected in aqueous while alcohol soluble was in ethanolic extracts. Flavonoids were not detected at all in the grasses by the selected methodology. Rest of the phytochemicals were increased up to the moderate levels of salinity 100 mM to 200 mM then decreased up to 300 mM of NaCl but in some grasses reveres of this has been analyzed. Some phyto-chemicals increased with the increase in the salinity.
Elicitation, the process of stimulating plants to enhance the production of valuable secondary metabolites, has emerged as a significant avenue in the field of plant biotechnology. This review paper provides a comprehensive examination of elicitation, encompassing its mechanisms, the imperative for its utilization, and the diverse array of elicitors employed, including abiotic, biotic, and nanoparticle-based agents. By exploring the intricate signaling pathways and molecular responses triggered by external stimuli in this review, we gain insights into how plants tailor their metabolite production in reaction to their environment. Intricately intertwined with the mechanisms, the types of elicitors utilized are extensively discussed. Abiotic elicitors, encompassing physical factors and chemicals, biotic elicitors involving microbe-derived molecules, plant hormones and symbiotic microorganisms, and the emerging application of nanoparticles as elicitation agents are explored. The review further examines the application of these elicitors in both in-vitro and in-vivo cultures, showcasing their practical utility in controlled laboratory settings and real-world environments. By assessing the efficacy of diverse elicitors, this paper provides valuable insights into tailoring elicitation strategies to enhance secondary metabolite yields for various applications. Addressing the limitations and leveraging emerging technologies will undoubtedly steer elicitation research towards innovative breakthroughs, further enhancing our capacity to harness plants for sustainable and efficient secondary metabolite production.
Medicinal Plants: Microbial Interactions, Molecular Techniques, and Therapeutic Trends is a comprehensive exploration of the fascinating world of medicinal plants, their therapeutic advancements, and the application of molecular techniques to unlock their full potential. This book is structured into three illuminating sections, each shedding light on different facets of this rapidly developing field.
Section 1: Exploring Plant-Microbe Interactions
Covers the relationship between microbes and plants, the historical context and the pivotal role of microbes in shaping the future of medicinal plants. Discover the diverse array of bacteria associated with these plants and grasp their significance in enhancing the medicinal value of plants.
Section 2: Harnessing Molecular Techniques
Covers cutting-edge molecular techniques such as genome editing and modern breeding methods to optimize the genetic traits of medicinal plants. By understanding these techniques, readers will learn how to enhance plant growth, yield and quality.
Section 3: Nanotechnology for Therapeutic Enhancement
Covers nanotechnology and its transformative impact on medicinal plants. The section highlights emerging nano-engineering technology that can revolutionize the therapeutic properties of these plants.
Medicinal Plants: Microbial Interactions, Molecular Techniques, and Therapeutic Trends is a book for Interdisciplinary readers: students, scientists, academics, and industry professionals alike.
Whether you're a student, scientist, academic, or industry professional, this book is your gateway to the evolving world of plant-based medicine.
Nursery raising of ornamental flowering annuals using soilless substrates is becoming a lucrative industry worldwide. Pakistan, being an agricultural country, still doesn't have its own cheaper and sustainable soilless substrates for high quality nursery production. Therefore, a study was conducted at University of Agriculture, Faisalabad, Pakistan and Purdue University, West Lafayette, IN, USA, for development and evaluation of a cheaper, sustainable, and easily available soilless substrate using agricultural by-products along with its value addition by inoculating it with plant growth promoting rhizobacteria. For this purpose, coco-coir, rice hulls ash and composted sugarcane pressmud were combined in ratio of 1:1:1; v/v/v and were inoculated with Bacillus (MN-54), Enterobacter (MN-17) and Trichoderma species in 108 CFU mL−1 and 107 CFU mL−1 solutions. These inoculated treatments along with uninoculated treatment, a negative control (sand: silt; 1:1, v/v) were evaluated for their physico-chemical and nursery raising aspects for ‘Inca’ marigold and ‘Giant Dahlia Flowered’ zinnia. The study revealed that Enterobacter MN-17 (107 CFU mL−1) inoculated substrate had highest water holding capacity (72.9 %), total porosity (81.04 %) and organic matter contents (92.9 %). Whereas, Trichoderma spp. (108 CFU mL−1) inoculated substrate had better electrical conductivity (1.59 dS m−1) and pH (5.64) and resulted in highest final germination percentage (93.6 %), with greatest seedling vigor index (2195), seedling shoot length (10.2 cm), root length (12.5 cm) and leaf total chlorophyll contents (57.4 SPAD) in marigold. However, in zinnia, Enterobacter MN-17 (107 CFU mL−1) inoculated substrate resulted in highest germination percentage (98.3 %), greatest seedling vigor index (3302), seedling root length (15.8 cm) and leaf total chlorophyll contents (55.8 SPAD), whereas same strain with 108 CFU mL−1 took shortest time for mean germination (3.8 days). In conclusion, substrate enriched with Enterobacter MN-17 (107 CFU mL−1) or Trichoderma spp. (108 CFU mL−1) may be used to produce high quality ornamental flowering annuals nursery.
Numerous ecological factors influence a plant’s ability to live and grow, in which dryness is a substantial constraint on plant growth in arid and semi-arid areas. In response to a specific environmental stress, plants can use the most effective bacteria to support and facilitate their growth and development. Today, plant growth promoting rhizobacteria (PGPR) is widely used to reduce drought stress on plant growth. In this study, the effects of drought on Festuca ovina L. germination, growth, and nutrient absorption were investigated using PGPR in a factorial test with a completely random design under four water regimes. Soil water content was kept at 100% FC (field capacity), 70% FC (FC), 50% FC, and 30% FC. The treatments were inoculated with Azotobacter vinelandii, Pantoea agglomerans+Pseudomonas putida, and a mixture of bio-fertilizers. Results showed that the effects of drought stress were significantly reduced (P<0.05) when A. vinelandii and P. agglomerans+P. putida were used separately, however, the combined treatment of bio-fertilizers had a greater influence on seed germination than the single application. P. agglomerans+P. putida under 30% FC condition resulted in higher increases in stem, root length, and plant dry biomass. The highest uptake of nutrients was observed for the combined treatment of bio-fertilizers under 30% FC condition. Therefore, the use of A. vinelandii and P. agglomerans+P. putida, applied separately or combined, increased tolerance to drought stress in F. ovina by increased germination indices, dry weight, stem length, and root length. Because of the beneficial effects of PGPR on the growth characteristics of plants under drought conditions and the reduction of negative effects of drought stress, inoculating F. ovina seeds with Azotobacter and Pseudomonas is recommended to improve their growth and development characteristics under drought conditions. PGPR, as an affordable and environmentally friendly method, can improve the production of forage in water-stress rangelands.
Aloe vera L. (Aloe barbadensis Miller) is a very common water deficit-resistant plant which has immense medicinal properties. It is a fleshy plant belonging to the Liliaceae family. Aloe barbadensis has enormous medicinal value. According to historical records, it has been used in folk and traditional medicine in different parts and regions of the world for ages. Aloe vera is widely used in Ayurvedacharya and Unani medicine. The plant is a rich source of potent medicinal phytocomponents, each with pronounced medicinal properties. Primarily, Aloe gel is considered one of Mother Nature's magical formulations for treating and curing various health ailments, including skin diseases, hair fall, indigestion, inflammation, and many others. Studies revealed that the use of biofertilizers significantly improves the growth and development of the Aloe plant. The quality and quantity of the constituents of Aloe vera gel are also reported to improve significantly with the use of biofertilizers. Biofertilizers, when used alone or in combination, are reported to influence the length, width, biomass, and phytoconstituents of the leaves of the plant. Biofertilizers, which are environment friendly and more effective on Aloe, can thus be considered a better substitute for other fertilizers for boosting the qualitative and quantitative yield of the magical medicinal plant, Aloe barbadensis.
Ecosystem functions directly depend upon biophysical as well as biogeochemical reactions occurring at the soil-microbe-plant interface. Environment is considered as a major driver of any ecosystem and for the distributions of living organisms; therefore, any change in climate may potentially alter the composition of communities i.e., plants, soil microbes, and the interactions between them. Since the impacts of global climate change are not short-term, it is indispensable to appraise its effects on different life forms including soil-microbe-plant interactions. This article highlights the crucial role that microbial communities play in interacting with plants under environmental disturbances, especially thermal and water stress. We reviewed that in response to the environmental changes, actions and reactions of plants and microbes vary markedly within an ecosystem. Changes in environment and climate like warming, CO2 elevation, and moisture deficiency impact plant and microbial performance, their diversity, and ultimately community structure. Plant and soil feedbacks also affect interacting species and modify community composition. The interactive relationship between plants and soil microbes is critically important for structuring terrestrial ecosystems. The anticipated climate change is aggravating the living conditions for soil microbes and plants. The environmental insecurity and complications are not short-term and limited to any particular type of organism. Therefore, we have appraised effects of climate change on the soil inhabiting microbes and plants in a broader prospect. This article highlights the unique qualities of tripartite interaction between plant-soil-microbe under climate change.
Plant secondary metabolites (PSMs) such as terpenes and phenolic compounds are known to have numerous ecological roles, notably in defence against herbivores, pathogens and abiotic stresses and in interactions with competitors and mutualists. This book reviews recent developments in the field to provide a synthesis of the function, ecology and evolution of PSMs, revealing our increased awareness of their integrative role in connecting natural systems. It emphasises the multiple roles of secondary metabolites in mediating the interactions between organisms and their environment at a range of scales of ecological organisation, demonstrating how genes encoding for PSM biosynthetic enzymes can have effects from the cellular scale within individual plants all the way to global environmental processes. A range of recent methodological advances, including molecular, transgenic and metabolomic techniques, are illustrated and promising directions for future studies are identified, making this a valuable reference for researchers and graduate students in the field.
Plant secondary metabolites (PSMs) such as terpenes and phenolic compounds are known to have numerous ecological roles, notably in defence against herbivores, pathogens and abiotic stresses and in interactions with competitors and mutualists. This book reviews recent developments in the field to provide a synthesis of the function, ecology and evolution of PSMs, revealing our increased awareness of their integrative role in connecting natural systems. It emphasises the multiple roles of secondary metabolites in mediating the interactions between organisms and their environment at a range of scales of ecological organisation, demonstrating how genes encoding for PSM biosynthetic enzymes can have effects from the cellular scale within individual plants all the way to global environmental processes. A range of recent methodological advances, including molecular, transgenic and metabolomic techniques, are illustrated and promising directions for future studies are identified, making this a valuable reference for researchers and graduate students in the field.
Plant secondary metabolites (PSMs) such as terpenes and phenolic compounds are known to have numerous ecological roles, notably in defence against herbivores, pathogens and abiotic stresses and in interactions with competitors and mutualists. This book reviews recent developments in the field to provide a synthesis of the function, ecology and evolution of PSMs, revealing our increased awareness of their integrative role in connecting natural systems. It emphasises the multiple roles of secondary metabolites in mediating the interactions between organisms and their environment at a range of scales of ecological organisation, demonstrating how genes encoding for PSM biosynthetic enzymes can have effects from the cellular scale within individual plants all the way to global environmental processes. A range of recent methodological advances, including molecular, transgenic and metabolomic techniques, are illustrated and promising directions for future studies are identified, making this a valuable reference for researchers and graduate students in the field.
Plant secondary metabolites (SMs) play crucial roles in plant-environment interactions and contribute greatly to human health. Global climate changes are expected to dramatically affect plant secondary metabolism, yet a systematic understanding of such influences is still lacking. Here, we employed medicinal and aromatic plants (MAAPs) as model plant taxa and performed a meta-analysis from 360 publications using 1828 paired observations to assess the responses of different SMs levels and the accompanying plant traits to elevated carbon dioxide (eCO2 ), elevated temperature (eT), elevated nitrogen deposition (eN) and decreased precipitation (dP). The overall results showed that phenolic and terpenoid levels generally respond positively to eCO2 but negatively to eN, while the total alkaloid concentration was increased remarkably by eN. By contrast, dP promotes on the levels of all SMs, while eT exclusively exerts a positive influence on the levels of phenolic compounds. Further analysis highlighted the dependence of SM responses on different moderators such as plant functional types, climate change levels or exposure durations, mean annual temperature and mean annual precipitation. Moreover, plant phenolic and terpenoid responses to climate changes could be attributed to the variations of C/N ratio and total soluble sugar levels, while the trade-off supposition contributed to SM responses to climate changes other than eCO2 . Taken together, our results predicted the distinctive SM responses to diverse climate changes in MAAPs, and allowed us to define potential moderators responsible for these variations. Further, linking SM responses to C-N metabolism and growth-defence balance provided biological understandings in terms of plant secondary metabolic regulation.
Main Conclusion
The responses of plants to different abiotic stresses and mechanisms involved in their mitigation are discussed. Production of osmoprotectants, antioxidants, enzymes and other metabolites by beneficial microorganisms and their bioengineering ameliorates environmental stresses to improve food production.
Abstract
Progressive intensification of global agriculture, injudicious use of agrochemicals and change in climate conditions have deteriorated soil health, diminished the microbial biodiversity and resulted in environment pollution along with increase in biotic and abiotic stresses. Extreme weather conditions and erratic rains have further imposed additional stress for the growth and development of plants. Dominant abiotic stresses comprise drought, temperature, increased salinity, acidity, metal toxicity and nutrient starvation in soil, which severely limit crop production. For promoting sustainable crop production in environmentally challenging environments, use of beneficial microbes has emerged as a safer and sustainable means for mitigation of abiotic stresses resulting in improved crop productivity. These stress-tolerant microorganisms play an effective role against abiotic stresses by enhancing the antioxidant potential, improving nutrient acquisition, regulating the production of plant hormones, ACC deaminase, siderophore and exopolysaccharides and accumulating osmoprotectants and, thus, stimulating plant biomass and crop yield. In addition, bioengineering of beneficial microorganisms provides an innovative approach to enhance stress tolerance in plants. The use of genetically engineered stress-tolerant microbes as inoculants of crop plants may facilitate their use for enhanced nutrient cycling along with amelioration of abiotic stresses to improve food production for the ever-increasing population. In this chapter, an overview is provided about the current understanding of plant–bacterial interactions that help in alleviating abiotic stress in different crop systems in the face of climate change. This review largely focuses on the importance and need of sustainable and environmentally friendly approaches using beneficial microbes for ameliorating the environmental stresses in our agricultural systems.
Catharanthus roseus is one of the most extensively investigated medicinal plants. Increase the concentrations of TIAs in plant organs, by biotic and abiotic treatments, is an important breeding objective on C. roseus. The effect of plant growth promoting rhizobacteria, Pseudomonas fluorescens and Azospirillum brasilense separately and in combination along with moisture treatment at two levels were tested in Catharanthus roseus as a factorial experiment based on randomized complete block design in three replications. Effect of treatments was evaluated 30 days after applying moisture treatments on some of morphological traits and Tdc and Str genes expression at the root of plant using qRT-PCR reaction. Water deficit significantly increased root length but it had no significant effect on the expression of these genes. Treatment with A. brasilense in normal condition enhanced length, volume and surface of roots, also significantly increased Str key gene expression. P. fluorescens had a positive and significant effect on the expression of the studied genes under normal and stress conditions compared to the control plants, despite the decrease in the amount of morphological traits. P. fluorescens and A. brasilense, separately, performed better in terms of their effects on the expression of the studied genes and increased the gene expression in normal and stress conditions compared to control plants. It is expected that by increasing the expression of Tdc and Str genes, the product of these genes as well as the final products of TIAs biosynthetic pathway, including ajmalicin content enhance at the root of periwinkle plant.
The effect of Pseudomonas koreensis IGPEB 17 and arbuscular mycorrhizal fungi (AMF) on plant growth and physiological properties of ginger (Zingiber officinale) in net house conditions was investigated. The experiment included four treatments including P.
koreensis IGPEB 17, arbuscular mycorrhizal fungi (AMF) biofertilizer and combination of P. koreensis IGPEB 17 and AMF treatment. The result indicated that P. koreensis IGPEB 17 had positive effects on plant growth-promoting traits such as P-solubilization, protease, amylase, IAA, and ACC deaminase production. Moreover, P. koreensis IGPEB 17 showed ability in producing lipase and cellulase. The P. koreensis IGPEB 17 significantly increased plant height (57.6%), the leaf number (28.1%), leaf length (23.3%) and leaf width (35.7%) compared to control treatment. However, the combination of P. koreensis IGPEB 17 and AMF treatment significantly increased the height of plant, the number of leaf, the length of leaf and the width of leaf by 68.4%, 42.3%, 30.2%, and 54.7%, respectively compared to control treatment. Furthermore, dual inoculation of P. koreensis IGPEB 17 and AMF significantly enhanced the chlorophyll a (76.5%), chlorophyll b (71.2%), total chlorophyll (73.3%), and carotenoid content (74.7%), respectively rather than control. In conclusion, results showed that dual inoculation of P. koreensis IGPEB 17 strain and AMF increased plant growth and physiological traits of ginger plants compared to inoculation with P. koreensis IGPEB 17 and AMF alone.
Rhizosphere is a hot spot for plant-microbe-soil information exchange and material exchange, and is inseparable from plant growth and development. The purpose of this paper is to review the progress of research concerning the rhizosphere microorganisms of medicinal plants, the types of root secretions and their interactions. The majority of medicinal plants have strong obstacles to continuous cropping, so we reviewed studies on the effects of root exudates and microbial communities in rhizospheres on continuous cropping obstacles. In the context of continuous cropping, medicinal plants secrete secondary metabolites in order to resist adversity stress, which accumulate in the soil and produce autotoxic effects. These autotoxins have a concentration effect on medicinal plants; the higher the concentration, the stronger the inhibitory effect on growth. They are also highly species-specific, with autotoxins differing from one medicinal plant to another. As a result of these autotoxins, the structure of the rhizospheric soil microbial community is destabilized, resulting in an increase in the number of harmful microorganisms and a decrease in the number of beneficial microorganisms. The present study provides an insight into the interactions between medicinal plants and rhizospheric microorganisms.
Hymenaea courbaril L. is a fruit species widely distributed throughout the Neotropics and possibly tolerant to a range of environmental variations, including adaptation to dry soils. Therefore, we hypothesized that growth-promoting microorganisms isolated from the roots and rhizosphere of this plant affect its resistance to water suppression. We aimed at testing our hypothesis by biopriming the seeds of this species using microorganisms previously tested for the expression of functional traits associated with growth promotion, followed by cultivating this plant under a water deficit regime for three months. The inoculation effect was evaluated in terms of growth parameters, photosynthetic pigments, photochemical performance, and gas exchange. Bacteria, particularly isolates of Bacillus cereus, B. thuringiensis, and Paenibacillus alvei, were more effective than fungi in promoting growth in H. courbaril L. under water suppression. However, the inoculation treatments with B. thuringiensis and Curvularia intermedia minimized the water deficit-induced photochemical damage, with the observed values being similar to or higher than those observed in irrigated plants. In general, microbial inoculation increased the photosynthetic rate and stomatal conductance in leaves, and the C. intermedia and B. thuringiensis inoculation induced the rates of net assimilation and carboxylation efficiency that also exceeded the average observed in irrigated plants. These microorganisms potentially assist H. courbaril L. in its dispersal through water-poor soils and, based on the plant growth-promoting rhizobacterial effect observed in B. thuringiensis, could be applied in agriculture as stress reducers and growth promoters. Aiming the future production of inoculants, we indicate the use of B. thuringiensis and C. intermedia, however, we suggest that phytopathogenicity studies are previously carried out with this endophytic strain of C. intermedia. Alternatively, this work showed the expression of phytopathogenic traits by the rhizospheric fungus Penicillium shearii, possibly stimulated by drought stress conditions.
In the present investigation, ‘rosea’ and ‘alba’ varieties of Catharanthus roseus (L.) G. Don. seeds were grown with different concentrations (15, 30, 45 and 60 mM) of sodium chloride (NaCl), in order to study the effects of salinity on germination behaviour, seedling vigour (root and shoot length), lipid peroxidation (LPO) and proline metabolism. It was found that germination was delayed at lower salinity levels and inhibited at higher salinity regimes. NaCl treatment caused a serious decrease in the early seedling growth by means of reduced seedling vigour at higher salinity levels. The LPO was estimated as thiobarbituric acid reactive substances (TBARS) and found increased under salt stress. Glycine betaine (GB) and proline (PRO) contents significantly accumulated in both the varieties of seedlings under salt stress. Under NaCl stress, the activity of proline oxidase (PROX) decreased and the γ-glutamyl kinase (γ-GK) activity increased.
The effect of paclobutrazol, a plant growth regulator, on antioxidant defense system was investigated in Catharanthus roseus (L.) G. Don. plants subjected to NaCl stress. The growth parameters were significantly reduced under 80mM NaCl treatment;
however, this growth inhibition was less in paclobutrazol-treated (15mgl−1plant−1) plants. The non-enzymatic antioxidants ascorbic acid and reduced glutathione were affected under NaCl stress and they increased
significantly under paclobutrazol treatment when compared to NaCl treated as well as control plants (P≤0.05). The activity of antioxidant enzyme ascorbate peroxidase showed a significant enhancement under salinity stress.
The catalase activity decreased in roots of NaCl-treated plants, but recovered with paclobutrazol treatment. The results suggested
that paclobutrazol have significant role in contributing salt stress tolerance of C. roseus by improving the components of antioxidant defense system.
The research was performed to define the effect of water deficit on early growth, biomass allocation and biochemical constituents, proline metabolism and yield of five varieties of bhendi (Abelmoschus esculentus (L.) Moench.) plants. We found that there were significant differences in early growth, dry matter accumulation, biochemical constituents and proline metabolism among the five varieties. The root length, shoot length, total leaf area, fresh weight and dry weight were significantly reduced under drought-induced stress treatment. The proline content and g-glutamyl kinase were significantly enhanced and proline oxidase activities were reduced. Drought stress caused an increase in the free amino acid and glycinebetaine content.
Decreasing relative water content (RWC) of leaves progressively decreases stomatal conductance (gs), slowing CO2 assimilation (A) which eventually stops, after which CO2 is evolved. In some studies, photosynthetic potential (Apot), measured under saturating CO2, is unaffected by a small loss of RWC but becomes progressively more inhibited, and less stimulated by elevated CO2, below a threshold RWC (Type 1 response). In other studies, Apot and the stimulation of A by elevated CO2 decreases progressively as RWC falls (Type 2 response). Decreased Apot is caused by impaired metabolism. Consequently, as RWC declines, the relative limitation of A by g(s) decreases, and metabolic limitation increases. Causes of decreased Apot are considered. Limitation of ribulose bisphosphate (RuBP) synthesis is the likely cause of decreased Apot at low RWC, not inhibition or loss of photosynthetic carbon reduction cycle enzymes, including RuBP carboxylase/oxygenase (Rubisco). Limitation of RuBP synthesis is probably caused by inhibition of ATP synthesis, due to progressive inactivation or loss of Coupling Factor resulting from increasing ionic (Mg2+) concentration, not to reduced capacity for electron or proton transport, or inadequate trans-thylakoid proton gradient (ApH). Inhibition of Apot by accumulation of assimilates or inadequate inorganic phosphate is not considered significant. Decreased ATP content and imbalance with reductant status affect cell metabolism substantially: possible consequences are discussed with reference to accumulation of amino acids and alterations in protein complement under water stress.
The influence of the arbuscular mycorrhizal fungus Glomus deserticola on the water relations, gas exchange parameters, and vegetative growth of Rosmarinus officinalis plants under water stress was studied. Plants were grown with and without the mycorrhizal fungus under glasshouse conditions and subjected to water stress by withholding irrigation water for 14 days. Along the experimental period, a significant effect of the fungus on the plant growth was observed, and under water stress, mycorrhizal plants showed an increase in aerial and root biomass compared to non-mycorrhizal plants. The decrease in the soil water potential generated a decrease in leaf water potential (psi(l)) and stem water potential (psi(x)) of mycorrhizal and non-mycorrhizal plants, with this decrease being lower in mycorrhizal water-stressed plants. Mycorrhization also had positive effects on the root hydraulic conductivity (Lp) of water stressed plants. Furthermore, mycorrhizal-stressed plants showed a more important decrease in osmotic potential at full turgor (psi(os)) than did non-mycorrhizal-stressed plants, indicating the capacity of osmotic adjustment. Mycorrhizal infection also improved photosynthetic activity (Pn) and stomatal conductance (g(s)) in plants under water stress compared to the non-mycorrhizal-stressed plants. A similar behaviour was observed in the photochemical efficiency of PSII (Fv/Fm) with this parameter being lower in non-mycorrhizal plants than in mycorrhizal plants under water stress conditions. In the same way, under water restriction, mycorrhizal plants showed higher values of chlorophyll content than did non-mycorrhizal plants. Thus, the results obtained indicated that the mycorrhizal symbiosis had a beneficial effect on the water status and growth of Rosmarinus officinalis plants under water-stress conditions.
Plant secondary metabolites are unique sources for pharmaceuticals, food additives, flavors, and other industrial materials. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Understanding signal transduction paths underlying elicitor-induced production of secondary metabolites is important for optimizing their commercial production. This paper summarizes progress made on several aspects of elicitor signal transduction leading to production of plant secondary metabolites, including: elicitor signal perception by various receptors of plants; avirulence determinants and corresponding plant R proteins; heterotrimeric and small GTP binding proteins; ion fluxes, especially Ca2+ influx, and Ca2+ signaling; medium alkalinization and cytoplasmic acidification; oxidative burst and reactive oxygen species; inositol trisphosphates and cyclic nucleotides (cAMP and cGMP); salicylic acid and nitric oxide; jasmonate, ethylene, and abscisic acid signaling; oxylipin signals such as allene oxide synthase-dependent jasmonate and hydroperoxide lyase-dependent C12 and C6 volatiles; as well as other lipid messengers such as lysophosphatidylcholine, phosphatidic acid, and diacylglycerol. All these signal components are employed directly or indirectly by elicitors for induction of plant secondary metabolite accumulation. Cross-talk between different signaling pathways is very common in plant defense response, thus the cross-talk amongst these signaling pathways, such as elicitor and jasmonate, jasmonate and ethylene, and each of these with reactive oxygen species, is discussed separately. This review also highlights the integration of multiple signaling pathways into or by transcription factors, as well as the linkage of the above signal components in elicitor signaling network through protein phosphorylation and dephosphorylation. Some perspectives on elicitor signal transduction and plant secondary metabolism at the transcriptome and metabolome levels are also presented.
Pseudomonas fluorescens 2-79 and P. aureofaciens 30-84 produce the antibiotic phenazine-1-carboxylic acid and suppress take-all, an important root disease of wheat caused by Gaeumannomyces graminis var. tritici. To determine whether the antibiotic is produced in situ, wheat seeds were treated with strain 2-79 or 30-84 or with phenazine-nonproducing mutants or were left untreated and then were sown in natural or steamed soil in the field or growth chamber. The antibiotic was isolated only from roots of wheat colonized by strain 2-79 or 30-84 in both growth chamber and field studies. No antibiotic was recovered from the roots of seedlings grown from seeds treated with phenazine-nonproducing mutants or left untreated. In natural soils, comparable amounts of antibiotic (27 to 43 ng/g of root with adhering soil) were recovered from roots colonized by strain 2-79 whether or not the pathogen was present. Roots of plants grown in steamed soil yielded larger bacterial populations and more antibiotic than roots from natural soils. In steamed and natural soils, roots from which the antibiotic was recovered had significantly less disease than roots with no antibiotic, indicating that suppression of take-all is related directly to the presence of the antibiotic in the rhizosphere.
Bacteria associated with the plant rhizosphere may have beneficial effects on plant growth by providing nutrients and growth factors, or by producing antibiotics and siderophores, which antagonize phytopathogenic fungi and bacteria. There is considerable experimental support for the idea that plant growth promoting bacteria may be used as bio–fertilizers or biological disease control agents to increase agricultural yields. Recent advances in our understanding of the molecular biology of the systems responsible for plant growth stimulation are opening the way to strain improvement by genetic engineering.
A clear definition of induced disease resistance is lacking, even though the area has been extensively researched and described. The lack of a precise definition leads to potential confusion on whether an underlying mechanism for biological control is induced resistance. We propose definitions, which were developed at a NATO Advanced Research Workshop on biological control, for induced disease resistance and related terms. These definitions are intended to invoke debate and increase effective communication among investigators of induced resistance.
Proteomics, the systematic analysis of (differentially) expressed proteins, is a tool for the identification of proteins involved in cellular processes. Proteomics has already been used for many different applications in plant sciences, including the study of proteins of biosynthetic pathways leading to secondary metabolites. In secondary metabolism, many enzymes are involved, often working in close collaboration to catalyse cascades of reactions. Besides the enzymes, transport and regulatory proteins are also involved, which makes the proteome an essential topic for studying metabolic pathways. Proteomics technology is based on high-throughput techniques for the separation and identification of proteins, allowing an integral study of many proteins at the same time. For the separation of protein mixtures the most powerful technique available is two-dimensional polyacrylamide gel electrophoresis: after separation, proteins can be subsequently identified by mass spectrometry (MS). The increasing amount of genome sequence data has to be followed by deciphering the function of the genes and proteins. Studying differential expression by proteomics is a complementary tool for functional analysis. In this review practical aspects and applications of proteomics in plant sciences, with particular emphasis on secondary metabolism, are discussed. Copyright © 2000 John Wiley & Sons, Ltd.
The reversed-phase high-performance liquid chromatographic characteristics of eight indole alkaloids of Catharanthus roseus have been investigated, with reference to the eluting power, pH and the ionic strength of the eluent. The relative elution volumes of the alkaloids can be changed by altering one of these parameters.Crude alkaloid extracts of cells are fractionated on a silica column prior to analysis. The principal alkaloids, ajmalicine and serpentine, are reversed from the silica in different fractions. On chromatography of these fractions with isocratic eluents the two alkaloids elute within 20 min. Their peak heights are linearly correlated with the amount injected and thus can be used for their quantitation.
A two-stage process for enhanced ajmalicine production in elicited Catharanthus roseus cell cultures was developed in shake-flasks and a bioreactor. By using combined elicitor treatment of an Aspergillum niger mycelium and tetramethyl ammonium bromide, yields of ajmalicine were 48 mg l–1, 52 mg l–1 and 33 mg l–1, respectively in 500-ml flasks, 1000-ml flasks and a 20-l airlift bioreactor. The peroxidase and superoxide dismutase activities decreased in elicited cell cultures but catalase and lipoxygenase activities increased in these cultures. The combined elicitor treatment also caused a significant increase of malondialdehyde content in cell cultures.
The effect of different growth regulators on growth and the production of terpenoid indole alkaloids as well as some enzymes involved in the biosynthesis were studied in Catharanthus roseus seedlings. The seedlings were grown on MS solid medium containing different concentrations of each growth regulator for a period of one month. Extracted alkaloids were analyzed by HPLC for determination of terpenoid indole alkaloid quantities. Continuous availability of growth regulators induced different alkaloids with variable effects among the regulators. Gibberellic acid at concentration of either 5.8M or 11.6M resulted in elongation of shoots with lowering the number of leaves. Abscisic acid has a retardant effect on growth. Ethylene did not effect the growth pattern at concentration of 100M but seedlings were not tolerant to higher concentrations. Methyljasmonate reduced the growth of the root system. Methyljasmonate was a general inducer for all alkaloids and increased the activity of strictosidine glucosidase. Ethylene applications promoted the pathways towards ajmalicine, serpentine, tabersonine and vindoline. Similar effect as for ethylene was observed for abscisic acid. Salicylic acid treatment increased the production of serpentine, tabersonine and higher concentration of salicylic acid induced vindoline accumulation. Peroxidase activity was also induced by salicylic acid. Gibberellic acid has little effect on alkaloid levels.
A few bacterial species are known to produce and excrete hydrogen cyanide (HCN), a potent inhibitor of cytochrome c oxidase and several other metalloenzymes. In the producer strains, HCN does not appear to have a role in primary metabolism and is generally considered a secondary metabolite. HCN synthase of proteobacteria (especially fluorescent pseudomonads) is a membrane-bound flavoenzyme that oxidizes glycine, producing HCN and CO2. The hcnABC structural genes of Pseudomonas fluorescens and P. aeruginosa have sequence similarities with genes encoding various amino acid dehydrogenases/oxidases, in particular with nopaline oxidase of Agrobacterium tumefaciens. Induction of the hcn genes of P. fluorescens by oxygen limitation requires the FNR-like transcriptional regulator ANR, an ANR recognition sequence in the -40 region of the hcn promoter, and nonlimiting amounts of iron. In addition, expression of the hcn genes depends on a regulatory cascade initiated by the GacS/GacA (global control) two-component system. This regulation, which is typical of secondary metabolism, manifests itself during the transition from exponential to stationary growth phase. Cyanide produced by P. fluorescens strain CHA0 has an ecological role in that this metabolite accounts for part of the biocontrol capacity of strain CHA0, which suppresses fungal diseases on plant roots. Cyanide can also be a ligand of hydrogenases in some anaerobic bacteria that have not been described as cyanogenic. However, in this case, as well as in other situations, the physiological function of cyanide is unknown.
Vesicular-arbuscular mycorrhizal fungi can affect the water balance of both amply watered and droughted host plants. This
review summarizes these effects and possible causal mechanisms. Also discussed are host drought resistance and the influence
of soil drying on the fungi.
The effects of triadimefon, a triazole compound on the antioxidant potentials and root alkaloid ajmalicine content were studied in two varieties, rosea and alba of Catharanthus roseus (L.) G. Don., an important medicinal plant. The plants of both the varieties were subjected to 15 mg l−1 triadimefon treatment by soil drenching on 53, 68 and 83 days after planting (DAP). The plants were harvested on 60, 75 and 90 days after planting and the antioxidant potentials and ajmalicine content were estimated. The antioxidant potentials viz., ascorbic acid (AA), α-tocopherol and reduced glutathione (GSH) were found increased under triadimefon treatment. The antioxidant enzymes like superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) activities showed slight changes in both the varieties under triadimefon treatment when compared to control plants. Indole alkaloid ajmalicine content increased significantly under triadimefon treatment. The increase in ajmalicine content was more in rosea variety than in alba variety. These preliminary results suggest that, the application of triadimefon may be a useful tool to increase the alkaloid production in medicinal plants.
The functional, spatial and temporal complexity of pathogen defence in plants is becoming ever-more apparent. Functional complexity begins with the exogenous signals perceived from the pathogen, continues with the mechanisms of signal perception and signal transduction, and results in extensive ‘reprogramming’ of cellular metabolism, involving large changes in gene activity. The spatial organization of these reactions is similarly complex and affects intracellular compartmentation, the fate of cells and, ultimately, the tissues that surround the infection site. The highly dynamic nature of the response adds temporal complexity. Thus, pathogen defence entails a major shift in metabolic activity, rather than altered expression of a few unique, defence-related genes. The observed complexity serves as a paradigm of the flexibility and plasticity of plant metabolism.
Salt and drought stress signal transduction consists of ionic and osmotic homeostasis signaling pathways, detoxification (i.e., damage control and repair) response pathways, and pathways for growth regulation. The ionic aspect of salt stress is signaled via the SOS pathway where a calcium-responsive SOS3-SOS2 protein kinase complex controls the expression and activity of ion transporters such as SOS1. Osmotic stress activates several protein kinases including mitogen-activated kinases, which may mediate osmotic homeostasis and/or detoxification responses. A number of phospholipid systems are activated by osmotic stress, generating a diverse array of messenger molecules, some of which may function upstream of the osmotic stress-activated protein kinases. Abscisic acid biosynthesis is regulated by osmotic stress at multiple steps. Both ABA-dependent and -independent osmotic stress signaling first modify constitutively expressed transcription factors, leading to the expression of early response transcriptional activators, which then activate downstream stress tolerance effector genes.
Glasshouse experiments were conducted to assess the influence of Pseudomonas fluorescens, Azotobacter chroococcum, Azospirillum brasilense and composted organic fertilizers (cow dung, horse dung, goat dung and poultry manure) alone and in combination on the multiplication of Meloidogyne incognita and growth of tomato. P. fluorescens was better at improving tomato growth and reducing galling and nematode multiplication than A. chroococcum or A. brasilense. Among composted organic fertilizers, poultry manure resulted in less galling and nematode multiplication than occurred with goat dung. However, composted goat dung was better in reducing nematode multiplication and improving plant growth than horse dung. Cow dung was the composted organic fertilizer least effective in reducing galling and nematode multiplication. Poultry manure with P. fluorescens was the best combination for the management of M. incognita on tomato but improved management of M. incognita can also be obtained if goat dung is used with P. fluorescens or poultry manure with A. chroococcum.
Plant-associated microbial diversity encompasses symbionts, protecting their host against various aggressions. Mycorrhizal and rhizospheric microorganisms buffer effects of soil toxic compounds and soil-borne pathogens. Endophytic bacteria and fungi, some of which are vertically inherited through seeds, take part in plant protection by acting directly on aggressive factors (mainly pathogens and herbivores) or by enhancing plant responses. Plant protective microbial symbionts determine the ecological success of plants; they drastically modify plant communities and related trophic webs. This review suggests approaches to improve the inventory of diversity and functions of in situ plant-associated microorganisms.
Water is a key factor influencing the yield and quality of crops. Plants mainly adapt to water deficits by biochemical changes and osmotic adjustment (OA). Research on drought tolerance of field crops has been done intensively, but there is little work to be done in medical plants. Traditional Chinese medicine (TCM) has a long history of several thousand years. TCM is playing an important role in daily life in China and applied widely in clinical experience on the globe. More and more wild medical plants are cultivated and introduced. It is known that ecological and environmental conditions are vital to cultivation and efficient component accumulation of medical plants. This study is concerned about biochemical changes of three genotypes of Radix Astragali during water deficient periods and we evaluated the relative ability of their drought tolerance on the above basis. We analyzed the effect of soil water deficits on antioxidant enzymes activity and osmoregulation substances in R. Astragali leaves of three genotypes collected on day 0, 5, 10, 15, 20 and 25 after onset of water deprivation. Under water deficient conditions, biochemical changes include protecting enzyme system, for instance superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). Osmoregulation matters include proline (Pro) and soluble sugar. Antioxidant enzyme activities and Pro, and soluble sugar content correlated between water deficient degree and time course. Antioxidant enzyme activities increased before 20 days, then decreased at the end of experiment. Proline content increased gradually, and soluble sugar content reached the highest on day 20. The order of the ability of drought tolerance in three genotypes of R. Astragali is Mongolia>Wild>Hebei by using index of drought tolerance. The research results are instructive for cultivation and introduction of R. Astragali under different conditions of water status.
The Madagascar periwinkle [Catharanthus roseus (L.) G. Don] is a commercially important horticultural flower species and is the only source of the monoterpenoid indole alkaloids (MIAs), vinblastine and vincristine, key pharmaceutical compounds used to combat a number of different cancers. The present study uses high performance liquid chromatography for metabolic profiling of the MIAs extracted from seedlings and young leaves of 50 different flowering cultivars of C. roseus to show that, except for a single low vindoline cultivar (Vinca Mediterranean DP Orchid), they accumulate similar levels of MIAs. Further enzymatic studies with extracts from young leaves and from developing seedlings show that the low vindoline cultivar has a 10-fold lower tabersonine-16-hydroxylase activity than those of C. roseus cv. Little Delicata. It is concluded that rapid metabolic and more selective enzymatic profiling of Catharanthus mutants could be useful for the identification of a range of altered MIA biosynthesis lines.
The effect of the arbuscular mycorrhizal (AM) fungus, Glomus versiforme, on growth and reactive oxygen metabolism of trifoliate orange (Poncirus trifoliata) seedlings was studied in potted plants under well-watered (WW) and water stressed (WS) conditions. Water stress significantly decreased root colonization. Shoot dry weight, plant height and stem diameter were higher in AM than in non-AM seedlings regardless of the water status. Inoculation with G. versiforme increased root dry weight and leaf number per plant of WW seedlings. There was less malondialdehyde (MDA) concentration in leaves and roots of AM seedlings, as well as lower hydrogen peroxide (H(2)O(2)) and superoxide anion radical (O(2)(-)) concentrations in AM roots under WW and WS conditions. AM inoculation did not affect the H(2)O(2) and O(2)(-) concentrations of WW leaves. Whether WS or not, AM symbiosis notably increased the guaiacol peroxidase (G-POD) activity of leaves, glutathione reductase (GR) activity of leaves and ascorbate peroxidase (APX) activity of roots. AM infection also markedly increased the APX activity of WS leaves. Soluble proteins and glutathione (GSH) in leaves and roots and ascorbate (ASC) in leaves were higher in WW AM than in WW non-AM seedlings. AM infection also enhanced the ASC and GSH contents of leaves and roots in WS seedlings. Cross-tolerance might occur in AM plants and be enhanced by AM symbiosis. Our results suggest that the increased concentrations of antioxidant enzymes and non-enzymatic antioxidants found in AM plants may serve to protect the organism against oxidative damage, enhancing drought tolerance.
Drought is one of the major ecological factors limiting crop production and food quality globally, especially in the arid and semi-arid areas of the world. Wheat is the staple food for more than 35% of world population and wheat cultivation is mainly restricted to such zones with scarcity of water, so wheat anti-drought physiology study is of importance to wheat production, food safety and quality and biotechnological breeding for the sake of coping with abiotic and biotic conditions. The current study is to investigate changes of anti-oxidative physiological indices of 10 wheat genotypes at tillering stage. The main results and conclusion of tillering stage in terms of activities of POD, SOD, CAT and MDA content as followed: (1) 10 wheat genotypes can be generally grouped into three kinds (A-C, respectively) according to their changing trend of the measured indices; (2) A group performed better drought resistance under the condition of treatment level 1 (appropriate level), whose activities of anti-oxidative enzymes (POD, SOD, CAT) were higher and MDA lower; (3) B group exhibited stronger anti-drought under treatment level 2 (light-stress level), whose activities of anti-oxidative enzymes were higher and MDA lower; (4) C group expressed anti-drought to some extent under treatment level 3 (serious-stress), whose activities of anti-oxidative enzymes were stronger, MDA lower; (5) these results demonstrated that different wheat genotypes have different physiological mechanisms to adapt themselves to changing drought stress, whose molecular basis is discrete gene expression profiling (transcriptom). The study in this respect is the key to wheat anti-drought and biological-saving water in worldwide arid and semi-arid areas; (6) POD, SOD, and CAT activities and MDA content of different wheat genotypes had quite different changing trend at different stages and under different soil water stress conditions, which was linked with their origin of cultivation and individual soil water threshold, which will provide better reference to selecting proper plant species for eco-environmental construction and crops for sustainable agriculture in arid and semi-arid areas.
In the present study, a pot culture experiment was conducted to estimate the ameliorating effect of propiconazole (PCZ) on drought stress in cowpea (Vigna unguiculata (L.) Walp.) plants. From 30 days after sowing (DAS), the plants were subjected to 3, 6 and 9 days interval drought (DID) stress and drought stress with PCZ at 15 and 15 mg l(-1) PCZ alone and 1 day interval irrigation was kept as control. The plant samples were collected on 34 DAS (3 DID), 37 DAS (6 DID) and 40 DAS (9 DID). The plants were separated into root, stem and leaf for estimating the antioxidant contents and activities of antioxidant enzymes. Individual and combined drought stress and PCZ treatments increased ascorbic acid (AA), alpha-tocopherol (alpha-toc) contents, superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and polyphenol oxidase (PPO) activities when compared to control. The PCZ treatment mitigated the adverse effects of drought stress by increasing the antioxidant potentials and thereby paved the way for overcoming drought stress in V. unguiculata plants.
Catharanthus roseus (L.) G. Don plants were grown in different water regimes in order to study the drought induced osmotic stress and proline (PRO) metabolism, antioxidative enzyme activities and indole alkaloid accumulation. The plants under pot culture were subjected to 10, 15 and 20 days interval drought (DID) stress from 30 days after sowing (DAS) and regular irrigation was kept as control. The plants were uprooted on 41DAS (10DID), 46DAS (15DID) and 51DAS (20DID). The drought stressed plants showed increased aminoacid (AA), glycine betaine (GB) and PRO contents and decreased proline oxidase (PROX) and increased gamma-glutamyl kinase (gamma-GK) activities when compared to control. The antioxidative enzymes like peroxidase (POX) and polyphenol oxidase (PPO) increased to a significant level in drought stressed plants when compared to control. The drought stressed C. roseus plants showed an increase in total indole alkaloid content in shoots and roots when compared to well-watered control plants. Our results suggest that the cultivation of medicinal plants like C. roseus in water deficit areas would increase its PRO metabolism, osmoregulation, defense system and the level of active principles.
Plant growth promoting rhizobacteria (PGPR) are commonly used as inoculants for improving the growth and yield of agricultural crops, however screening for the selection of effective PGPR strains is very critical. This study focuses on the screening of effective PGPR strains on the basis of their potential for in vitro auxin production and plant growth promoting activity under gnotobiotic conditions.
A large number of bacteria were isolated from the rhizosphere soil of wheat plants grown at different sites. Thirty isolates showing prolific growth on agar medium were selected and evaluated for their potential to produce auxins in vitro. Colorimetric analysis showed variable amount of auxins (ranging from 1.1 to 12.1 mg l-1) produced by the rhizobacteria in vitro and amendment of the culture media with l-tryptophan (l-TRP), further stimulated auxin biosynthesis (ranging from 1.8 to 24.8 mg l-1). HPLC analysis confirmed the presence of indole acetic acid (IAA) and indole acetamide (IAM) as the major auxins in the culture filtrates of these rhizobacteria. A series of laboratory experiments conducted on two cv. of wheat under gnotobiotic (axenic) conditions demonstrated increases in root elongation (up to 17.3%), root dry weight (up to 13.5%), shoot elongation (up to 37.7%) and shoot dry weight (up to 36.3%) of inoculated wheat seedlings. Linear positive correlation (r = 0.99) between in vitro auxin production and increase in growth parameters of inoculated seeds was found. Based upon auxin biosynthesis and growth-promoting activity, four isolates were selected and designated as plant growth-promoting rhizobacteria (PGPR). Auxin biosynthesis in sterilized vs nonsterilized soil inoculated with selected PGPR was also monitored that revealed superiority of the selected PGPR over indigenous microflora. Peat-based seed inoculation with selected PGPR isolates exhibited stimulatory effects on grain yields of tested wheat cv. in pot (up to 14.7% increase over control) and field experiments (up to 27.5% increase over control); however, the response varied with cv. and PGPR strains.
It was concluded that the strain, which produced the highest amount of auxins in nonsterilized soil, also caused maximum increase in growth and yield of both the wheat cv.
This study suggested that potential for auxin biosynthesis by rhizobacteria could be used as a tool for the screening of effective PGPR strains.
Natural and induced genetic variation in the synthesis of alkaloids and other secondary metabolites, in: Improvement of Oilseed and Industrial Crops by Induced Mutations
- A Levy
A. Levy, Natural and induced genetic variation in the synthesis of alkaloids and other secondary metabolites, in: Improvement of Oilseed and Industrial Crops by Induced Mutations, IAEA, Vienna, 1982, pp. 213–222.
Effect of seed treatment with native diazotrophs on the seedling parameters of Senna and Ashwagandha
- A Lakshmanan
- K Govindarajan
- K Kumar
A. Lakshmanan, K. Govindarajan, K. Kumar, Effect of seed treatment with native diazotrophs on the seedling parameters of Senna and Ashwagandha, Crop Res. 30 (2005) 119–123.
Investigation on plant growth promoting rhizobacteria of tea rhizosphere
- U Chakraborthy
- B N Chakraborty
- P R Chowdhury
- C Tongden
- M Basnet
U. Chakraborthy, B.N. Chakraborty, P.R. Chowdhury, C. Tongden, M.
Basnet, Investigation on plant growth promoting rhizobacteria of tea rhizosphere, in: 6th International Workshop on PGPR, IISR, Calicut, Kerala,
2003, pp. 78–82.
Effect of Azospirillum on growth and yield of chilli (Capsicum annuum L.) cultivar Pusa Jawala
- B C Deka
- G C Bora
- A Shadeque
B.C. Deka, G.C. Bora, A. Shadeque, Effect of Azospirillum on growth and yield of chilli (Capsicum annuum L.) cultivar Pusa Jawala, Haryana, J. Hort. Sci. 38 (1992) 41–46.
Effect of FYM and biofertilizers on dry root and seed yield of Ashwagandha (Withania somnifera)
- N J Thosar
- V G Ingle
- J C Jadhav
N.J. Thosar, V.G. Ingle, J.C. Jadhav, Effect of FYM and biofertilizers on dry root and seed yield of Ashwagandha (Withania somnifera), Crop Prot. Prod. 1 (2005) 27–28.
- J W Kloepper
- R Lifshitz
- J A Kuc
J.W. Kloepper, R. Lifshitz, J.A. Kuc, Proposed definitions related to induced
disease resistance, Biocontrol Sci. Tech. 2 (1992) 349–351.
Reversed phase-high performance liquid chromatographic characteristics of indole alkaloids from cell suspension cultures of Catharanthus roseus
- Renoudin
J. Renoudin, Reversed phase-high performance liquid chromatographic
characteristics of indole alkaloids from cell suspension cultures of Catharanthus roseus, J. Chromatogr. 291 (1984) 165–174.
Symbiotic microorganisms, a key for ecological success and protection of plants
- M Andreselosse
- E Baudoin
- P Vandenkoornhyse
M. Andreselosse, E. Baudoin, P. Vandenkoornhyse, Symbiotic microorganisms, a key for ecological success and protection of plants, C. R. Biol.
327 (2004) 639–648.
Variations in water status, gas exchange, and growth in Rosmarinus officinalis plants with Glomus deserticola under drought conditions
- M J Sanchen-Blanco
- T Ferrandes
- M A Morales
- A Morte
- J Alarcon
M.J. Sanchen-Blanco, T. Ferrandes, M.A. Morales, A. Morte, J. Alarcon,
Variations in water status, gas exchange, and growth in Rosmarinus officinalis plants with Glomus deserticola under drought conditions, J. Plant
Physiol. 161 (2004) 675–682.
Natural and induced genetic variation in the synthesis of alkaloids and other secondary metabolites
- Levy
Development of microbial consortium for improvement of growth, yield and alkaloid content of ashwagandha (Withania somnifera, Dunal
H. Gopal, Development of microbial consortium for improvement of
growth, yield and alkaloid content of ashwagandha (Withania somnifera,
Dunal), J. Herb Spices Med. Plants 8 (2004) 38–43.
Effect of seed treatment with native diazotrophs on the seedling parameters of Senna and Ashwagandha
- Lakshmanan
Effect of FYM and biofertilizers on dry root and seed yield of Ashwagandha (Withania somnifera)
- Thosar
Propiconazole induced changes in antioxidant metabolism and drought stress amelioration in Vigna unguiculata (L.) Walp
- Manivannan
Effect of Azospirillum on growth and yield of chilli (Capsicum annuum L.) cultivar Pusa Jawala, Haryana
- Deka
Proteomics in plant biotechnology and secondary metabolism research
- Jacobs
Water relations, drought and vesicular-arbuscular mycorrhial symbiosis
- Auge