ArticleLiterature Review

Plant latex and other exudates as plant defense systems: Roles of various defense chemicals and proteins contained therein

Authors:
To read the full-text of this research, you can request a copy directly from the author.

Abstract

Plant latex and other exudates are saps that are exuded from the points of plant damage caused either mechanically or by insect herbivory. Although many (ca. 10%) of plant species exude latex or exudates, and although the defensive roles of plant latex against herbivorous insects have long been suggested by several studies, the detailed roles and functions of various latex ingredients, proteins and chemicals, in anti-herbivore plant defenses have not been well documented despite the wide occurrence of latex in the plant kingdom. Recently, however, substantial progress has been made. Several latex proteins, including cysteine proteases and chitin-related proteins, have been shown to play important defensive roles against insect herbivory. In the mulberry (Morus spp.)-silkworm (Bombyx mori) interaction, an old and well-known model system of plant-insect interaction, plant latex and its ingredients--sugar-mimic alkaloids and defense protein MLX56--are found to play key roles. Complicated molecular interactions between Apocynaceae species and its specialist herbivores, in which cardenolides and defense proteins in latex play key roles, are becoming more and more evident. Emerging observations suggested that plant latex, analogous to animal venom, is a treasury of useful defense proteins and chemicals that has evolved through interspecific interactions. On the other hand, specialist herbivores developed sophisticated adaptations, either molecular, physiological, or behavioral, against latex-borne defenses. The existence of various adaptations in specialist herbivores itself is evidence that latex and its ingredients function as defenses at least against generalists. Here, we review molecular and structural mechanisms, ecological roles, and evolutionary aspects of plant latex as a general defense against insect herbivory and we discuss, from recent studies, the unique characteristics of latex-borne defense systems as transport systems of defense substances are discussed based on recent studies.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the author.

... Latex serves as a defense against herbivorous insects by its chemical content and by flooding the insect or its mouth parts with the sticky fluid. Konno [17] discussed in detail the rich chemical defense of the latex of various angiosperm families but omitted latex from schizogenous channels. Besides being more numerous, plant species that occur in the tropics are greater latex producers than those found in temperate regions. ...
... some latex-bearing plants defy the traditional classification of laticifers," for example, some cacti (Mammillaria) "have epithelia-lined, schizolysigenous latex ducts." Konno [17], however, simply asserts that "by definition," latex is an exudate in elongated laticifers cells, which is historically hardly correct. Similarly, Prado and Demarco [30] and Alencar et al. [31] using a definition based on anatomy and some histochemical dataconclude that the milky fluid in the ducts of Clusiaceae and Calophyllaceae is a "resin." ...
... This aqueous suspension is generally composed of numerous compounds belonging to a variety of classes, including inorganic constituents and primary compounds. Among the secondary compounds in these suspensions, terpenoids, fatty acids, aromatic compounds, and alkaloids are commonly found [13,17]. ...
... This has allowed them to survive throughout time in diverse ecosystems (Bucharova et al. 2016). Among these tools, plant exudates have attracted great interest due to their adaptive origin, having resulted from their co-evolution with other organisms, including insect herbivores and microorganisms (Konno 2011). Plant exudates represent one of the surface defense layers associated with both primary and secondary strategies such as superficial physical structures (hairs, trichomes, thorns) and specialized metabolites, respectively (Kant et al. 2015). ...
... For example, the concentration of bioactive metabolites of latex at damaged points before and upon an attack has been shown to be increased (Ball et al. 1997;Gorpenchenko et al. 2019;Hölscher et al. 2016). Latexes have also been recognized as reservoirs of defense-related enzymes (Konno 2011). Several cysteine and serine proteases, protease inhibitors, chitinases, lectins, and oxidases have been isolated and identified from these exudates (Pintus et al. 2010). ...
... The chemical composition of latexes includes three major categories of compounds: polyisoprene polymers (rubber), proteins, and low molecular weight specialized metabolites (Salomé-Abarca et al. 2019). Among these, proteins have been relatively more studied due to their evident biological functions against herbivores and pathogens (Konno 2011;Ramos et al. 2019). In the case of rubber, research has been focused on the coagulation process necessary for industrial purposes, but little is known about its role in defense mechanisms (Wahler et al. 2009). ...
Article
Full-text available
Based on the hypothesis that the variation of the metabolomes of latex is a response to selective pressure and should thus be affected differently from other organs, their variation could provide an insight into the defensive chemical selection of plants. Metabolic profiling was used to compare tissues of three Euphorbia species collected in diverse regions. The metabolic variation of latexes was much more limited than that of other organs. In all the species, the levels of polyisoprenes and terpenes were found to be much higher in latexes than in leaves and roots of the corresponding plants. Polyisoprenes were observed to physically delay the contact of pathogens with plant tissues and their growth. A secondary barrier composed of terpenes in latex and in particular, 24-methylenecycloartanol, exhibited antifungal activity. These results added to the well-known role of enzymes also present in latexes, show that these are part of a cooperative defense system comprising biochemical and physical elements.
... It has evolved separately at least 40 times and is found in~10% of all extant flowering plants (~20,000 species) as well as in gymnosperms, ferns, and even fungi (Agrawal and Konno, 2009;Dussourd, 2017). Traditionally, each new origin of latex has been thought to result in a major diversification event for the newly laticiferous plant group (Farrell et al., 1991;Konno, 2011), but this may not be true in all cases (Foisy et al., 2019). Latex is stored under high pressure in specialized, elongated cells called laticifers, primarily in the central, localized regions of the laticifer system (Pickard, 2008;Agrawal and Konno, 2009). ...
... When a leaf is damaged, for example by an insect herbivore, the pressurized latex is very rapidly deployed to the damaged area, where it exudes as a viscous sticky liquid that quickly clots (Agrawal and Konno, 2009;Konno, 2011). This clotting mechanism seals the wound, and the stickiness is a physical defense against insect herbivores, gumming up mouthparts, trapping legs, or even miring the entire insect (Dussourd, 1995;Agrawal and Konno, 2009;Konno, 2011;Dussourd, 2017). ...
... When a leaf is damaged, for example by an insect herbivore, the pressurized latex is very rapidly deployed to the damaged area, where it exudes as a viscous sticky liquid that quickly clots (Agrawal and Konno, 2009;Konno, 2011). This clotting mechanism seals the wound, and the stickiness is a physical defense against insect herbivores, gumming up mouthparts, trapping legs, or even miring the entire insect (Dussourd, 1995;Agrawal and Konno, 2009;Konno, 2011;Dussourd, 2017). For example, up to 30% of newly hatched monarch butterfly caterpillars die trapped in milkweed latex (Agrawal and Konno, 2009). ...
Article
Plants, insects, and their ecological interactions have been key components of global terrestrial ecosystems throughout geologic time. The arms race between latex-producing plants and latex-sabotaging insect herbivores—resulting in increasingly deadly latex in plants and progressively complex sabotaging behaviors in insects—is one such ecological interaction that is important in modern ecosystems. However, while latex has been identified in the fossil record, ancient latex-sabotaging behavior has not previously been described. Here we report on the discovery of four fossil leaves from the Eocene Geiseltal brown coals in Germany preserved with branched laticifer systems and damage indicative of latex-sabotaging insect behavior. Two types of damage are evident on the compressions of dicot leaves assigned to the morphotype Apocynophyllum neriifolium Heer emend. Kunzmann et Heer. One fossil leaf shows repeated, regularly spaced vein cuts along the midrib, while three other leaves show continuous trenching across the leaf lamina. These damage patterns are recognized as pertaining to previously described Damage Types for repeated hole feeding on the leaf midrib and for the narrow, trenched feeding of the leaf lamina, although they had not been associated with latex-bearing structures in previous work. It is specifically the co-occurrence of these damage types and the branched laticiferous system in the Geiseltal leaves described here that point to latex-sabotaging insect behavior. The Eocene age of the Geiseltal leaves with these types of insect damage is likely close to the time in which laticifers became widespread among flowering plants, suggesting a rapid evolutionary response by insect herbivores.
... En premier lieu, elles produisent un latex blanchâtre, le plus souvent irritant, jouant un rôle défensif vis-à-vis des insectes et des herbivores. [148][149][150] Au niveau botanique, les espèces du genre Euphorbia se caractérisent par leurs inflorescences originales appelées cyathium ( Figure 17). Celles-ci miment l'aspect d'une fleur grâce au regroupement d'organes mâles et femelles au sein d'un involucre caliciforme associé à des bractées. ...
... Cette propriété a pour but de défendre la plante contre les insectes et les phytopathogènes, mais aussi de faciliter la cicatrisation. 148 Par ailleurs, les métabolites présents dans le latex jouent un rôle dissuasif visà-vis des herbivores. Chez l'Homme, le latex d'Euphorbia est fortement irritant pour les yeux et les muqueuses. ...
Thesis
Le chikungunya est une maladie transmise par des moustiques du genre Aedes (dont A. albopictus, dit "moustique tigre"). Cette maladie provoque d'intenses fièvres et des douleurs articulaires chroniques fortement invalidantes. Les moustiques potentiellement vecteurs du virus du chikungunya (CHIKV) sont des espèces invasives qui, à la faveur du réchauffement climatique, se sont récemment implantés dans plusieurs régions du monde, dont la région méditerranéenne. Sa présence constitue un terreau favorable à la survenue d'épidémie. A l'heure actuelle, il n'existe ni vaccin, ni traitement médicamenteux efficace. Toutefois, des articles scientifiques ont récemment rapporté que des esters de diterpène isolés du genre Trigonostemon (Euphorbiaceae), avaient une activité inhibitrice de la réplication du CHIKV.Dans le cadre de ces travaux de thèse, des extraits de plantes du genre Euphorbia de Corse ont été étudiés dans le but d'isoler de nouvelles molécules douées d'activité antivirale sur la réplication du CHIKV. En collaboration avec le Dr. P. Leyssen (KU Leuven, Belgique), l'évaluation de l'activité anti-CHIKV de 45 extraits, obtenus à partir de 11 Euphorbiaceae de Corse, a permis de mettre en évidence la forte activité inhibitrice et sélective de des extraits d'espèces du genre Euphorbia in cellulo. L'activité antivirale d'une série de 27 diterpènes de type phorboïde, disponibles commercialement, a également été étudiée. Les résultats ont montré que certains dérivés avaient une forte activité inhibitrice de la réplication du CHIKV, mais aussi sur celle du virus de l'immunodéficience humaine (VIH). Ces études ont permis d'une part, de déduire des relations structure-activité inédites et d'autre part, de soutenir l'hypothèse d'un mécanisme d'action anti-CHIKV impliquant la modulation des protéines kinases C (PKCs) par les phorboïdes. Dans le but de confirmer ou d'infirmer la présence des phorboïdes dans les extraits d'Euphorbia, une première méthode utilisant la chromatographie liquide (LC) haute performance couplée à un spectromètre de masse à trappe d'ions (MSn), a été développée à partir des composés standards. L'application de cette méthodologie a révélé qu'aucun des phorboïdes ciblés n'était présent dans les extraits d'Euphorbia. Ainsi, une seconde procédure LC-MSn a été mise en œuvre afin de détecter - de manière non ciblée - différents types d’esters diterpéniques.
... Identification of signaling molecules influencing the differentiation of laticifer cells and NR biosynthesis of NR would be very useful. Latex appears to play a defensive role in responses to herbivores, insects, and pathogens (Agrawal and Konno, 2009;Konno, 2011) and rubber particles may play an important role in defense forming sticky masses at wound sites to entrap insects or mire their mouthparts (Agrawal and Konno, 2009;Konno, 2011). Some pathogen-derived elicitors are known to increase the growth and secondary metabolites in a range of plants (Varma et al., 2012) and so may have the potential to enhance NR biosynthesis in in vitro plant cultures. ...
... Identification of signaling molecules influencing the differentiation of laticifer cells and NR biosynthesis of NR would be very useful. Latex appears to play a defensive role in responses to herbivores, insects, and pathogens (Agrawal and Konno, 2009;Konno, 2011) and rubber particles may play an important role in defense forming sticky masses at wound sites to entrap insects or mire their mouthparts (Agrawal and Konno, 2009;Konno, 2011). Some pathogen-derived elicitors are known to increase the growth and secondary metabolites in a range of plants (Varma et al., 2012) and so may have the potential to enhance NR biosynthesis in in vitro plant cultures. ...
Article
Natural rubber (NR, cis-1,4-polyisoprene) is applied in over 50,000 products. It has unique properties, which cannot be matched by synthetic rubber. The pará rubber tree (Hevea brasiliensis Muell. Arg.) belonging to the Euphorbiaceae family is currently the only commercial source of NR. Alternative rubber-producing sources and systems are required to increase the biological and geographic diversity of natural rubber production, especially because of H. brasiliensis need for specialized growth conditions and its susceptibility to fungal pathogens. After describing rubber-producing plants, laticifer cells, rubber particles, and NR biosynthesis, this review focuses on the current challenges and potential ways to improve rubber production from Taraxacum kok-saghyz, a strong candidate alternative NR crop in temperate regions. In vitro culture, genetic engineering, and focused gene editing are discussed, in the context of rubber biosynthesis, but complementary breeding research (including interspecific hybridization and polyploidy induction), will be needed to fully develop this new rubber crop.
... Herein, we found these lepidopterans on another lactiferous Euphorbiaceae species, Sebastiania brasiliensis, a native species widely distributed in Misiones and other states of Argentina (www.darwin.edu.ar). As the latex may work as a plant defense mechanism against insect herbivores [69], we suggest that Lonomia may have ways of sabotaging such a defensive role. The caterpillar L. obliqua contains protease inhibitors in its venomous structures [70], which may protect itself from toxic components in latex, such as cysteine and serine proteases [69,71]. ...
... As the latex may work as a plant defense mechanism against insect herbivores [69], we suggest that Lonomia may have ways of sabotaging such a defensive role. The caterpillar L. obliqua contains protease inhibitors in its venomous structures [70], which may protect itself from toxic components in latex, such as cysteine and serine proteases [69,71]. ...
Article
Full-text available
Background: Envenomation by the South American Lonomia saturniid caterpillars, named lonomism, constitutes an emerging and somewhat neglected public health issue in Argentina and neighboring countries. Considering that there is an intricate relationship between environment and human health in such cases, this study aimed to analyze the eco-epidemiological profile of 40 accidents and 33 occurrences of Lonomia spp. in Misiones (Argentina) between January 2014 and May 2020. Methodology/principal findings: We described the eco-epidemiological variables and characterized the abiotic scenario of such cases. Additionally, we obtained a density map that shows the punctual intensity of Lonomia records throughout Misiones. Most of the accidents occurred in the Department of Guaraní and involved male victims younger than 20 years old. The accidental/occasional occurrence of Lonomia spp. (considering both adult and caterpillar stages together) was significantly higher in the rural area, whereas only adult specimens were found in urban areas. We determined that the presence of this insect in Misiones is positively related to higher temperatures and solar radiation, and larger precipitation and evapotranspiration throughout the year. Conclusion/significance: This study represents an initial step towards the global understanding of lonomism as a public health problem in Argentina. It provides a map of the risk level for this envenomation in Misiones, which could help authorities address public health policy efforts to implement sustainable strategies for prevention and response to this threat in Northeastern Argentina and neighboring regions.
... In nature, about 8.9% of flowering plants from over 40 families (angiosperms) produce latex (Lew), often a milky fluid, which is constituted of a mixture of diverse chemical compounds and which acts as the plant's defense system against herbivorous insects, nematodes, and phytopathogenic fungi [56][57][58]. Latexes from different plant species show wide chemical and biochemical differences [59]. Most plants of the Apocynaceae family produce latex, including C. procera and C. gigantea. ...
... IC 50 against tested cancer cell lines: MCF-7 32.9 AE 2.4 nM [95]; Hs-683 8 nM; U-373 15 nM; HCT-15 16 AE 5 nM; LoVo 10 nM; A-549 74 nM [107]; T47D 8.24 AE 0.24 nM [100] Procegenin A (50) isolated from C. procera in Egypt [94]. IC 50 against tested cancer cell lines: A549 0.604 μM; HeLa 1.151 μM [94]Chemistry, Biological Activities, and Uses of Calotropis Latex amyrin(59) ...
Chapter
The traditional and current use of the latex of Calotropis procera and C. gigantea, two soft-wooded, xerophytic shrubs of the family Apocynaceae, are reviewed against the background of the plants’ chemical constituents and their biological activities. Due to their distinctive latex components, Calotropis plants have been considered a major resource in traditional medicine in many regions. The presence of high amounts of bioactive compounds, which include tannins, flavonoids, triterpenoids, and steroids in the latex of the Calotropis plants, has long been recognized. Peptides and proteins such as peroxidases, peptidases, protease inhibitors, osmotins, lysozymes, and chitinases are all well-studied enzymes associated with the defense system of Calotropis plants against herbivores and diseases. The chemistry and biological activities of the Calotropis plants are thought to be linked to external factors, including the geographic location and the developmental stage of the plant, the season of harvest as well as the storage of the harvested plant, which can lead to a considerable variation in the chemical constituents found.
... Latex is distributed throughout the plant in a special internal secretory system constituted by a series of elongated cells, called laticifers. By releasing their latex from laticifer cell combined to rubbers from parietal cytoplasm, latexbearing plants construct a protective mechanism against herbivores and microorganisms as well as wound cicatrisation [10,23]. A fast coagulation of latex revealed secretion efficiency to protect the plant [23,24]. ...
... By releasing their latex from laticifer cell combined to rubbers from parietal cytoplasm, latexbearing plants construct a protective mechanism against herbivores and microorganisms as well as wound cicatrisation [10,23]. A fast coagulation of latex revealed secretion efficiency to protect the plant [23,24]. ...
Article
Full-text available
Pergularia tomentosa is a perennial twining herb widely spread out arid and semiarid Tunisian regions. It is searched for its richness in enzymes, secondary metabolites, antifungal activity, and milk-clotting activity. Traditional use implies the fresh latex in wounding heals. The present study was aimed at identifying laticifer distribution in Pergularia tomentosa stems, leaves, and petioles. In the present study, the identification of latex extract’s components and its valorisation by estimation of phenolic content, flavonoids, and antioxidant activity are conducted. Anatomical structures proved the presence of laticifers in the aerial parts of Pergularia tomentosa. They are particularly observed along the pith and cortical parenchyma in stem, in leaf mesophyll, and in petiole phloem. Identified laticifers were characterized as nonarticulated. FTIR spectroscopy proves the presence of several functional groups in the latex and mainly the cis-1-4-isoprene monomer. Results suggested that Pergularia tomentosa latex contributes significantly as a source of phenol content (62.3 mg Eq GAE/g) and flavonoids (24.8 mg Eq QE/g). Scavenging free radicals of DPPH exhibited IC50 value of 12 μg/ml. In conclusion, latex extracted from Pergularia tomentosa can be implied in industry as a natural rubber. It can be used, also, in medicine as a therapeutic agent.
... By adding latex to media, Oghenekaro et al. (2020) identified that some genes had elevated expressions in R. microporus. Latex is a complex emulsion that includes a diversity of chemicals such as proteins, alkaloids, carbohydrates, oils, tannins, and resins that coagulate on exposure to air [50,51]. It is commonly produced by plants after tissue injury and serve as a defense against pathogens and pests [50,51]. ...
... Latex is a complex emulsion that includes a diversity of chemicals such as proteins, alkaloids, carbohydrates, oils, tannins, and resins that coagulate on exposure to air [50,51]. It is commonly produced by plants after tissue injury and serve as a defense against pathogens and pests [50,51]. Here we used the high expressed genes induced by latex treatment in R. microporus to infer the distributions of these genes in the seven fungi analyzed in our study. ...
Article
Full-text available
Saprophytic fungi (SPF) play vital roles in ecosystem dynamics and decomposition. However, because of the complexity of living systems, our understanding of how SPF interact with each other to decompose organic matter is very limited. Here we studied their roles and interactions in the decomposition of highly specialized substrates between the two genera Auriscalpium and Strobilurus fungi-colonized fallen pinecones of the same plant sequentially. We obtained the genome sequences from seven fungal species with three pairs: A. orientale-S. luchuensis, A. vulgare-S. stephanocystis and A. microsporum-S. pachcystidiatus/S. orientalis on cones of Pinus yunnanensis, P. sylvestris and P. armandii, respectively, and the organic profiles of substrate during decomposition. Our analyses revealed evidence for both competition and cooperation between the two groups of fungi during decomposition, enabling efficient utilization of substrates with complementary profiles of carbohydrate active enzymes (CAZymes). The Auriscalpium fungi are highly effective at utilizing the primary organic carbon, such as lignin, and hemicellulose in freshly fallen cones, facilitated the invasion and colonization by Strobilurus fungi. The Strobilurus fungi have genes coding for abundant CAZymes to utilize the remaining organic compounds and for producing an arsenal of secondary metabolites such as strobilurins that can inhibit other fungi from colonizing the pinecones.
... The impact of non-native mammal herbivores such as rats, rabbits or goats on island ecosystems has been widely studied on oceanic islands (Campbell and Donlan, 2005;Coblentz, 1978;Garzón-Machado et al., 2010;Shiels and Drake, 2015;Vitousek et al., 1997) and more recently Mediterranean island ecosystems (Gizicki et al., 2018). However, the impacts of herbivores-especially ungulates-are unpredictable, as the consequences of herbivory strongly depend on the local context and herbivory may even be necessary for conservation of plant communities in some situations Fernández-Lugo et al., 2013, 2011. Moreover, conservation of ungulates of taxonomic or economical interest may require specific management measures (Papadopoulos, 2002;Pérez-Solano et al., 2020). ...
... Some species exhibit induced resistance responses by increasing the total amount of latex present in their plant tissues, though the initial concentrations of triterpenoids in the latex remain the same. Additionally, some herbivores can tolerate low amounts of toxic compounds in their diet, and may prefer to graze on juvenile plants that invest more resources in growth than toxic compounds compared to adult plants (Konno, 2011). Nevertheless, the induced chemical response of the species remains unknown. ...
Article
Herbivory of insular plant communities by introduced animals has been widely studied for decades. Though their diet mainly includes palatable and highly nutritive species, goats will also eat plants that are toxic to other animals. Thus, severe affection of toxic species may indicate high herbivore pressure or a low quality of vegetative food. To evaluate whether herbivory damage to low-palatability shrubs could give us information about feral goat pressure on vegetation, we assessed the predation impact of feral goats on the shrub Euphorbia dendroides (Euphorbiaceae) on Mallorca Island (Spain). We aimed to investigate whether goats consume juvenile E. dendroides and affect their population structure and determine if the plants increase the concentrations of toxic compounds as an adaptation to herbivory. Overall, two experimental plots and analysis of eleven natural populations indicated E. dendroides is affected by ungulates and that the population structure change with the presence of feral goats. Euphorbia dendroides could be used as an ecological indicator to determine the extent of ungulate damage to vegetation or indicate poor food availability, and thus inform the maintenance of optimal animal populations. Depending on the management objective for the territory, E. dendroides could be used as an ecological indicator to determine the extent of ungulate damage to vegetation or indicate poor food availability for animals, and thus inform the maintenance of optimal animal populations.
... Plant laticifer cells are filled with latex (milky sap) that contains condensed defense substances [6,7]. The plant exudes latex immediately at the site of damage caused by an insect attack [7,8]. In folk herbal medicine, extracts and latex of C. majus are used to treat warts and condylomas caused by human papillomavirus (HPV) [9]. ...
... The column outlet was directly coupled to a Nanospray ion source operating in a data-dependent MS to MS/MS switch mode. Identification of proteins matching with the C. majus CDS database was performed (Cmajus 20150107_1; 209,790 sequences; 74,516,318 residues) [8,10] by using the MASCOT database search engine (Matrix Science, London, UK; www.matrixscience.com; accessed on 28 October 2021). ...
Article
Full-text available
Chelidonium majus L. is a latex-bearing plant used in traditional folk medicine to treat human papillomavirus (HPV)-caused warts, papillae, and condylomas. Its latex and extracts are rich in many low-molecular compounds and proteins, but there is little or no information on their potential interaction. We describe the isolation and identification of a novel major latex protein (CmMLP1) composed of 147 amino acids and present a model of its structure containing a conserved hydrophobic cavity with high affinity to berberine, 8-hydroxycheleritrine, and dihydroberberine. CmMLP1 and the accompanying three alkaloids were present in the eluted chromatographic fractions of latex. They decreased in vitro viability of human cervical cancer cells (HPV-negative and HPV-positive). We combined, for the first time, research on macromolecular and low-molecular-weight compounds of latex-bearing plants in contrast to other studies that investigated proteins and alkaloids separately. The observed interaction between latex protein and alkaloids may influence our knowledge on plant defense. The proposed toolbox may help in further understanding of plant disease resistance and in pharmacological research.
... In nature, about 8.9% of flowering plants from over 40 families (angiosperms) produce latex (Lew), often a milky fluid, which is constituted of a mixture of diverse chemical compounds and which acts as the plant's defense system against herbivorous insects, nematodes, and phytopathogenic fungi [56][57][58]. Latexes from different plant species show wide chemical and biochemical differences [59]. Most plants of the Apocynaceae family produce latex, including C. procera and C. gigantea. ...
... IC 50 against tested cancer cell lines: MCF-7 32.9 AE 2.4 nM [95]; Hs-683 8 nM; U-373 15 nM; HCT-15 16 AE 5 nM; LoVo 10 nM; A-549 74 nM [107]; T47D 8.24 AE 0.24 nM [100] Procegenin A (50) isolated from C. procera in Egypt [94]. IC 50 against tested cancer cell lines: A549 0.604 μM; HeLa 1.151 μM [94]Chemistry, Biological Activities, and Uses of Calotropis Latex amyrin(59) ...
Chapter
The traditional and current use of the latex of Calotropis procera and C. gigantea, two soft-wooded, xerophytic shrubs of the family Apocynaceae, are reviewed against the background of the plants’ chemical constituents and their biological activities. Due to their distinctive latex components, Calotropis plants have been considered a major resource in traditional medicine in many regions. The presence of high amounts of bioactive compounds, which include tannins, flavonoids, triterpenoids, and steroids in the latex of the Calotropis plants, has long been recognized. Peptides and proteins such as peroxidases, peptidases, protease inhibitors, osmotins, lysozymes, and chitinases are all well-studied enzymes associated with the defense system of Calotropis plants against herbivores and diseases. The chemistry and biological activities of the Calotropis plants are thought to be linked to external factors, including the geographic location and the developmental stage of the plant, the season of harvest as well as the storage of the harvested plant, which can lead to a considerable variation in the chemical constituents found.
... Part of the latex defense mechanism results from the presence of natural rubber in tremendous amounts; its stickiness and ability to clot at the site of damaged tissue act to defend the plant from the insect attack [13][14][15] . ...
Article
Full-text available
Ficus carica tree produces a white sap that is traditionally used for the treatment of skin conditions, such as warts. Ficus carica latex is considered a rich source of proteins and metabolites that have various pharmacological activities. Most of the latex pharmacological activities are attributed to its phenolic content, such as anticancer, antiviral, antioxidant, anti-angiogenic, hepatoprotective, and wound-healing activities. Moreover, Ficus carica latex contains proteases that are involved in the treatments of skin conditions, such as warts, and display antiparasitic activity. Additionally, chitinase enzymes and coumarins are isolated from Ficus carica latex and involved in the antimicrobial activities of latex.
... To date, it is still exploited in homeopathy and according to Foster et al. it can be used for liver and gallbladder disorders along with rheumatism and respiratory inflammations [87]. Although the molecular mechanism of C. majus latex compounds action is largely unknown, its antiparasitic, insecticidal, anti-neoplastic, antiproliferative, antimycotic, immunomodulating, and antiviral properties are well established [4,20,85,[88][89][90]. ...
Article
Full-text available
Latex, a sticky emulsion produced by specialized cells called laticifers, is a crucial part of a plant’s defense system against herbivory and pathogens. It consists of a broad spectrum of active compounds, which are beneficial not only for plants, but for human health as well, enough to mention the use of morphine or codeine from poppy latex. Here, we reviewed latex’s general role in plant physiology and the significance of particular compounds (alkaloids and proteins) to its defense system with the example of Chelidonium majus L. from the poppy family. We further attempt to present latex chemicals used so far in medicine and then focus on functional studies of proteins and other compounds with potential pharmacological activities using modern techniques such as CRISPR/Cas9 gene editing. Despite the centuries-old tradition of using latex-bearing plants in therapies, there are still a lot of promising molecules waiting to be explored.
... Compared to the latex cDNA libraries, 20% of the ESTs were expressed in leaf and latex ( Table 2). The matched EST might be due to the response to the pathogen, as latex plays a role in defence against pathogens and herbivores (Konno 2011). Based on Table 2, most EST samples were proteolytic enzymes followed by the inhibitors. ...
Article
Hevea brasiliensis is one of the most important agricultural commodities globally, heavily cultivated in Southeast Asia. Fatal leaf fall diseases cause aggressive leaf defoliation, linked to lower latex yield and death of crops before maturity. Due to the significant consequences of the disease to H. brasiliensis, the recent gene expression studies from four fall leaf diseases of H. brasiliensis were gathered; South American leaf blight, powdery mildew, Corynespora cassiicola and Phytophthora leaf fall disease. The differential analysis observed the pattern of commonly expressed genes upon fungi triggers using RT-PCR, DDRT-PCR, Real-time qRT-PCR and RNA-Seq. We have observed that RNA-Seq is the best tool to seek novel genes. Among the identified genes with defence-against fungi were pathogenesis-related genes such as β-1,3-glucanase and chitinase, the reactive oxygen species, and the phytoalexin biosynthesis. This manuscript also provided functional elaboration on the responsive genes and predicted possible biosynthetic pathways to identify and characterise novel genes in the future. At the end of the manuscript, the PCR methods and proteomic approaches were presented for future molecular and biochemical studies in the related diseases to H. brasiliensis.
... It might be due to the level and duration of the stress, which was not strong enough to induce significant alteration of ascorbate and glutathione metabolism. It leads to an assumption that laticifers, which is naturally part of plant defence against herbivory and pathogens (Konno, 2011;Ramos et al., 2019;Gracz-Bernaciak et al., 2021), are equipped with powerful scavenging system that can neutralize stress in a certain level and duration. Deng et al. (2015) reported that the GR2 gene was more expressed in bark than in latex. ...
... Results showed that the latex made total mortality at the highest dilution used of 1:250 in 5 days. Plant latex comprises of a substantial mixture of proteins and specialized products that include alkaloids, terpenoids, cardenolides, and many other components, most of which are toxic against insects and pathogens (Agrawal and Konno, 2009;Hua et al., 2015;Huber et al., 2015;Konno, 2011;Konno et al., 2006). ...
Article
Full-text available
p>Laboratory evaluation of Euphorbia bupleuroides latex as biopesticide against the red flour beetle (Tribolium castaneum) and khapra beetle (Trogoderma granarium) were evaluated at ambient temperature. The insecticidal activity of latex was determined by direct contact application. Different concentrations were prepared by dilution of 2.5, 5.0, 7.0 and 10.0 µl of latex into 0.1 ml acetone. 1 µl was pumped regularly in the thorax of different insects. The latex of E. bupleuroides showed insecticidal activity against T. granarium and T. castaneum. High levels of mortality were associated with the increase in the concentration and time of exposure as well. T. granarium adults are generally more prone to latex insecticidal effects than T. castaneum adults. After 6 days of exposure to E. bupleuroides latex, the LC50 recorded was 14.12 µl for T. granarium adults, and 14.7 µl for T. castaneum. LC90 numbers, on the other hand, were 38.8 µl for the former, and 51.44 µl for the latter.</p
... The percentage of rubber particles in a specific volume of latex is expressed as Dry Rubber Content (DRC). For the plant, latex is suggested to be part of the defense system from herbivores and pathogens (Konno, 2011;Ramos et al., 2019). Latex can be produced by 22 families of monocots and dicots covering +12,500 species (Lewinsohn, 1991). ...
Article
Full-text available
Indonesia is one of the major natural rubber-producing countries. The low rubber prices severely affect rubber agribusiness as farmers and rubber companies depend on latex as the only source of income. This condition leads to an unprecedented challenge to rubber agribusiness sustainability. This systematic review aims to encourage the use of part of rubber plants as a source of revenue for rubber plantations to maintain their sustainability. Non-latex parts of the rubber plant can be utilized, including latex serum and skim waste, parts of rubber seeds, and rubberwood. The strength of the ancillary product of Hevea brasiliensis is that the raw materials are abundant, yet the weakness is that the rubber companies have no experience exploiting them. The opportunity for utilizing is widely open, as many methods have been researched; however, the main thread is how to compete with the existing products. Therefore, careful market research and feasibility studies are recommended.
... 2019). In guayule, natural rubber is biosynthesized in stembark tissues [3], especially in response to abiotic and biotic stresses [4] such as cold, non-freezing temperatures [5][6][7]. Natural rubber biosynthesis requires the 15-carbon initiator, farnesyl pyrophosphate (FPP), and the 5-carbon monomer, isopentenyl pyrophosphate (IPP), both derived from the isoprenoid pathway. ...
Article
Full-text available
Production of natural rubber by Parthenium argentaum (guayule) requires increased yield for economic sustainability. An RNAi gene silencing strategy was used to engineer isoprenoid biosynthesis by downregulation of squalene synthase (SQS), such that the pool of farnesyl diphosphate (FPP) substrate might instead be available to initiate natural rubber synthesis. Downregulation of SQS resulted in significantly reduced squalene and slightly increased rubber, but not in the same tissues nor to the same extent, partially due to an apparent negative feedback regulatory mechanism that downregulated mevalonate pathway isoprenoid production, presumably associated with excess geranyl pyrophosphate levels. A detailed metabolomics analysis of isoprenoid production in guayule revealed significant differences in metabolism in different tissues, including in active mevalonate and methylerythritol phosphate pathways in stem tissue, where rubber and squalene accumulate. New insights and strategies for engineering isoprenoid production in guayule were identified.
... Although latex-producing laticifers provide a strong line of defense against most herbivores, some insects, especially those that specialize in feeding on specific host plants, have developed strategies to circumvent ingesting latex, illustrating the evolutionary arms race between plant-eating insects and host plants. Two such specialists, the caterpillars of the monarch butterfly (Danaus plexippus) and arctiids (Pygarctia roseicapitis), cut veins on their host plant's petiole in a behavior called trenching 41,42 , to allow the latex to leak from the wound, and then feed on the distal, latex-deficient portion of the leaf. ...
Article
Full-text available
As sessile organisms, plants evolved elaborate metabolic systems that produce a plethora of specialized metabolites as a means to survive challenging terrestrial environments. Decades of research have revealed the genetic and biochemical basis for a multitude of plant specialized metabolic pathways. Nevertheless, knowledge is still limited concerning the selective advantages provided by individual and collective specialized metabolites to the reproductive success of diverse host plants. Here we review the biological functions conferred by various classes of plant specialized metabolites in the context of the interaction of plants with their surrounding environment. To achieve optimal multifunctionality of diverse specialized metabolic processes, plants use various adaptive mechanisms at subcellular, cellular, tissue, organ and interspecies levels. Understanding these mechanisms and the evolutionary trajectories underlying their occurrence in nature will ultimately enable efficient bioengineering of desirable metabolic traits in chassis organisms. Decades of research have identified the biochemical basis of many plant specialized metabolic pathways. This Review highlights the biological context of these pathways and how recent advances have extended the new frontiers of phytochemistry.
... Plant latex often contains a variety of toxic compounds, such as alkaloids and proteases, which provide a defense against insect herbivory [5][6][7][8]. Mulberry latex contains high concentrations of alkaloidal sugar mimics such as 1,4-dideoxy-1,4-imino-D-arabinitol (D-AB1) and 1-deoxynojirimycin (DNJ) [9,10]. Sugar-mimic alkaloids adversely affect the growth of non-mulberry phytophagous insects with low dose, such as the Eri silkworm, by interfering with sugar metabolism [11][12][13]. ...
Article
Full-text available
The silk-spinning and Lepidopteran model insect Bombyx mori (Bombycidae) is a mulberry specialist. The BmSuc1 gene is the first β-fructofuranosidase (β-FFase) encoding gene identified in animals, and β-FFase acts as an essential sucrase for glycometabolism modulation in the silkworm larvae, involved in resistance to mulberry alkaloids. Glyphodes pyloalis Walker (Lepidoptera: Pyralidae) is an important mulberry pest leading to heavy economic loss of sericulture. However, no molecular or biochemical information is available about G. pyloalis β-FFase homologs. In this study, five β-FFase homologous genes in G. pyloalis were obtained. The genes GpSuc1a and GpSuc2c were expressed in the midgut; GpSuc2c encodes a truncated polypeptide. The expression and the localization of GpSUC1a in the midgut was characterized. Whereas recombinant GpSUC1a expressed in both Escherichia coli and BmN cells displayed little activity as compared with higher activity of BmSUC1, β-FFase activity in the larval midgut of G. pyloalis and GpSUC1a purified from the midgut were both confirmed. The data suggested that the activation of GpSUC1a is probably controlled by a more complicated post-translational regulation system in G. pyloalis larvae than that of BmSUC1 in B. mori. To study post-translational modifications (PTMs), GpSUC1a and BmSUC1 were purified from larval midguts using immunoprecipitation and subjected to LC-MS to perform PTMs analysis. Some putative N-glycosylated sites were found in GpSUC1a but none in BmSUC1, while there was more methylation in BmSUC1 than in GpSUC1a, indicating that such PTMs were supporting the differential β-FFases activities in these two mulberry feeding caterpillars.
... It is known that latex, which has pharmacological and insecticidal properties, contains a high rate and various secondary metabolites, produced by more than 20 thousand plant species [10]. The largest group of plants producing latex is the Euphorbiaceae family. ...
Article
Full-text available
The latex of the Euphorbia plant was used in this study to find an effective and natural new insecticide in combating Dentroctonus micans (Kug.), Which causes great damage to Picea orientalis forests. For this purpose; Euphorbia plant was collected from Erzurum and species identification was made. According to the species identification, the spurge plant was determined to be Euphorbia virgata, and then its latex was obtained. In this study; Different concentrations of latex (0, 25, 50 and 75%) were applied to the experimental groups prepared to have fifty D. micans larvae in each group, and the experiment was repeated twice. As a result of the application, the LD50 (25%, 50% and 75%) values, respectively; 0.01µl/ml, 0.196 µl/ml, 0.294 µl/ml. LD90 values were found as 0.18 µl/ml, 0.354 µl/ml, and 0.531 µl/ml. Although E. virgata latex has a toxic effect on the larvae at any concentration, the mortality rate increased as the concentration amount increased. GC-MS analysis was performed to determine the latex content of E. virgata. According to GC-MS analysis, in latex content; there are terpenes, flavonoids, alkaloids, amines, fatty acids, steroids and various alcohols. These bioactive substances in E. virgata latex showed toxic effects on larvae. As a result of the study, it was found that E. virgata latex can be used as a natural and effective insecticide in the fight against D. micans..
... Numerous documents mention that latexes contain multifunctional bioactive constituents [2,3] such as cardenolides, terpenoids, phenolics, and alkaloids, which are listed as cytotoxic, antibacterial, antifungal, anthelmintic activities, as well as insectrepellent potential. Moreover, latex also contains diverse primary metabolites such as polypeptides and proteins [4]. Latex is produced by the plant immediately after mechanical damage or insect herbivory. ...
Article
Full-text available
Natural origin molecules represent reliable and excellent sources to overcome some medicinal problems. The study of anticancer, anticoagulant, and antimicrobial activities of Thevetia peruviana latex were the aim of the current research. An investigation using high-performance liquid chromatography (HPLC) revealed that the major content of the flavonoids are rutin (11.45 µg/mL), quersestin (7.15 µg/mL), naringin (5.25 µg/mL), and hisperdin (6.07 µg/mL), while phenolic had chlorogenic (12.39 µg/mL), syringenic (7.45 µg/mL), and ferulic (5.07 µg/mL) acids in latex of T. peruviana. Via 1,1-diphenyl-2- picrylhydrazyl (DPPH) radical scavenging, the experiment demonstrated that latex had a potent antioxidant activity with the IC50 43.9 µg/mL for scavenging DPPH. Hemolysis inhibition was 58.5% at 1000 µg/mL of latex compared with 91.0% at 200 µg/mL of indomethacin as positive control. Negligible anticoagulant properties of latex were reported where the recorded time was 11.9 s of prothrombin time (PT) and 29.2 s of the activated partial thromboplastin time (APTT) at 25 µg/mL, compared with the same concentration of heparin (PT 94.6 s and APPT 117.7 s). The anticancer potential of latex was recorded against PC-3 (97.11% toxicity) and MCF-7 (96.23% toxicity) at 1000 μg/mL with IC50 48.26 μg/mL and 40.31 µg/mL, respectively. Disc diffusion assessment for antimicrobial activity recorded that the most sensitive tested microorganisms to latex were Bacillus subtilis followed by Escherichia coli, with an inhibition zone (IZ) of 31 mm with minimum inhibitory concentration (MIC) (10.2 μg/mL) and 30 mm (MIC, 12.51 μg/mL), respectively. Moreover, Candida albicans was sensitive (IZ, 28 mm) to latex, unlike black fungus (Mucor circinelloides). TEM examination exhibited ultrastructure changes in cell walls and cell membranes of Staphylococcus aureus and Pseudomonas aeruginosa treated with latex. Energy scores of the molecular docking of chlorogenic acid with E. coli DNA (7C7N), and Rutin with human prostate-specific antigen (3QUM) and breast cancer-associated protein (1JNX), result in excellent harmony with the experimental results. The outcome of research recommended that the latex is rich in constituents and considered a promising source that contributes to fighting cancer and pathogenic microorganisms.
... The latex is characterized by three major classes of secondary metabolites: hydroxyphenylacetate inositol esters with either two or three side chains (di-PIEs and tri-PIEs), the sesquiterpene lactone taraxinic acid β-d-glucopyranosyl ester (TA-G), and triterpene acetates (TritAc) (Huber et al., 2015). Latex is mainly connotated with defensive functions against herbivores and pathogens (Konno, 2011), and our previous work on the bioactivity and ecological role of the latex metabolites of T. officinale confirms this hypothesis (Bont et al., 2017;Huber, Bont, et al., 2016;Huber, Epping, et al., 2016). TA-G in particular reduces the attractiveness of T. officinale to white grubs and thereby increases plant performance (Huber, Epping, et al., 2016). ...
Article
Full-text available
Atmospheric pressure is an important, yet understudied factor that may shape plant ecology and evolution. By growing plants under controlled conditions at different experimental stations in the Swiss alps, we evaluated the impact of ecologically realistic atmospheric pressures between 660 and 950 hPa on the growth and defence of different dandelion populations. Low atmospheric pressure was associated with reduced root growth and defensive sesquiterpene lactone production. Defence suppression only occurred in populations originating from lower altitudes. Populations from higher altitudes constitutively produced less sesquiterpene lactones and did not suffer from suppression under low atmospheric pressure. Synthesis. We conclude that atmospheric pressure modulates root growth and defence traits, and that evolutionary history shapes plant phenotypic responses to atmospheric pressure. Our findings have important implications for our understanding of altitudinal gradients and the future use of plants as a source of food and bioactive metabolites in extraterrestrial habitats.
... microporus . Latex is a complex emulsion that includes a diversity of chemicals such as proteins, alkaloids, carbohydrates, oils, tannins, and resins that coagulate on exposure to air (Konno, 2011). It is commonly produced by plants after tissue injury and serve as a defense against pathogens and pests (Oghenekaro et al., 2020). ...
Preprint
Full-text available
Saprophytic fungi play vital roles in nutrient cycling and ecosystem dynamics. However, our understanding of how saprophytic fungi interact with each other to decompose organic matter is very limited. Here, we conducted field surveys of pinecone-colonizing/decomposing mushrooms, investigated the chemical compositions of decomposing pinecones, and analyzed seven new genomes of three pairs of mushrooms in the genera Auriscalpium and Strobilurus with substrate specificities. Each pair of mushrooms successively colonizes the pinecones of a different pine species: A. orientale-S. luchuensis on Pinus yunnanensis, A. vulgare-S. stephanocystis on Pinus sylvestris, and A. microsporum-S. pachcystidiatus/S. orientalis on Pinus armandii. Our analyses revealed evidence for both competition and cooperation between Auriscalpium and Strobilurus fungi during pinecone decomposition. Their successive colonization of the two fungi groups with complementary profiles of carbohydrate-active enzymes enabled efficient decomposition and utilization of pinecones. The Auriscalpium fungi are highly effective at utilizing the recalcitrant primary organic carbons such as lignin and hemicellulose in freshly fallen pinecones. The decomposition by Auriscalpium fungi enabled the successive colonization by Strobilurus fungi which can produce an arsenal of secondary metabolites such as strobilurins to inhibit other fungi and have abundant carbohydrate-active enzymes for effective utilization of the remaining organic compounds in pinecones.
... Its composition may include terpenoids, polysaccharides, alkaloids and proteins such as enzymes. Among these enzymes proteases are frequently found [18]. Lipid hydrolases are less commonly present, or at least, less investigated [19]. ...
Article
The present contribution investigates the biocatalytic performance of the lipase obtained from the latex of the native plant known as Araujia sericifera (ASL) in the hydrolysis followed by the esterification of released free fatty acids and transesterification of glycerides of sunflower waste cooking oil WCO. A specific enzymatic activity of 719.05 μmol mg⁻¹ h⁻¹ (60 % conversion of triglycerides towards free fatty acids) was obtained in the hydrolysis of WCO with 0.05 % of biocatalyst (typically, 10.0 g WCO and 5.0 mg of enzyme) and 50 % w/w of water added in 30 min of reaction at 25 °C in homogeneous type of reaction system. The lipase has the capacity to catalyze the hydrolysis of the triglycerides mainly towards monoglycerides and diglycerides in a lesser extent. The released FFAs and the remaining glycerides reacted in tandem by addition of short chain alcohols immediately after the hydrolysis (without addition of more enzyme to the reaction media). Above 90 % conversion of the FFAs was obtained with methanol, ethanol, n-propanol and n-butanol at contents as low as 1:0.2 oil: alcohol molar ratio at 25 °C. The transesterification of the remaining monoglycerides (about 20 %) was also observed although no further reaction of the triglycerides was detected even under a great excess of alcohol.
... It might be due to the level and duration of the stress, which was not strong enough to induce significant alteration of ascorbate and glutathione metabolism. It leads to an assumption that laticifers, which is naturally part of plant defence against herbivory and pathogens (Konno, 2011;Ramos et al., 2019;Gracz-Bernaciak et al., 2021), are equipped with powerful scavenging system that can neutralize stress in a certain level and duration. Deng et al. (2015) reported that the GR2 gene was more expressed in bark than in latex. ...
Article
Full-text available
Latex diagnosis (LD) is applied to optimize the natural rubber production and prevent tapping panel dryness (TPD), a physiological syndrome affecting latex production in Hevea brasiliensis. The reduced thiol content (RSH) is one of the biochemical parameters associated with the risk of TPD. However, RSH is difficult to interpret because of the influence of the environment. In order to better understand the regulation of antioxidants and to better interpret RSH, a key parameter of LD, this study analysed in latex both oxidised and reduced forms of ascorbic acid (AsA) and glutathione, and their cofactors as well as other latex diagnosis parameters in response to harvesting stress (tapping and ethephon stimulation) and TPD occurrence. The content of antioxidants in latex had a high variability among five rubber clones. The concentration in AsA was about ten times higher than GSH in laticifer, GSH accounting for about 50% of RSH. For short-term harvesting stress, RSH increased with tapping frequency and ethephon stimulation. TPD is associated with high latex viscosity and bursting of lysosomal particles called lutoids, as well as for several rubber clones with lower RSH and GSH contents. These results suggest that a high level of RSH shows the capacity of laticifer metabolism to cope with harvesting stress, while a drop in RSH is the sign of long stress related to lower metabolic activity and TPD occurrence. RSH remains an essential physiological parameter to prevent TPD when associated with reference data under low and high harvesting stress. This study paves the way to understand the role of AsA and GSH, and carry out genetic studies of antioxidants.
... Startingin the Eocene, some angwsperms also preserve fossilized remnants of latex. Latex, like amber, is a defensive exudate from plants that may deter arthropod herbivores through physical effects, such as gumming up insect mouthparts or chemical toxicity (Hagelet al. 2008;Konno 2011;Mithöferand Boland 2012). L.atex rarely fossilizes because, unlike resin, it does not polymerize (Labandeua 2014a); however, ruhher-rich latex can fossilize through a natural vulcanization process ( Mahlberg and Störr 1989). ...
... However, we recorded NO increased to galling tissues but at lower percent (10-15%) compared to other antioxidants. Peroxidase (POD) is widely distributed in plant latex [83] and regarded as a defense antioxidant. In galling tissue, POD is induced by various herbivore attacks [84,85] which eventually detoxificate ROS and protect tissue from oxidative damage [86]. ...
Article
Gall-inducing insects are highly specialized in modifying phenotypes in their hosts. Phytochemical manipulations in galling sites induce tissue growth and differentiation and also refurbish defense response in plant against herbivore infestation. Therefore, plant–herbivore interaction coevolves and gives rise to a chemical arms race by employing refined chemical defense and detoxification mechanisms in the plant. Under this contextual, we aimed to investigate how phytochemical gradients accumulate in galling sites than the non-galled tissue. Analyzing 18 phytochemicals from underdeveloped and developed foliar gall tissue morphs among three model plants, we report that phytochemical manipulation builds gradually from non-galled (non-infested) to underdeveloped gall (marginal infestation) and from underdeveloped to developed (high infestation) gall tissue. A complex chemical surge is played in galling tissue where the phytochemicals perform a dual role in promotion of tissue growth as well as in execution of endogenous defense.
Article
Despite the extensive studies on latex, some fundamental questions on their chemical specialization and the factors influencing this specialization have yet to be investigated. To address this issue, latexes and their bearing tissues from diverse species were profiled by 1HNMR and GC-MS. Additionally, the antiherbivory activity of these materials was tested against thrips (Frankliniella occidentalis Pergande, 1895). The multivariate data analysis showed a clear separation between latexes and leaves from the same species. Conversely, the chemical profiles of latexes from different species were highly similar, that is, they displayed much less metabolic species-specificity. These shared chemical profiles of latexes were reflected in their overall higher mortality index (80.4% ± 7.5) against thrips compared with their bearing tissues (55.5% ± 14.9). The metabolites correlated to the antiherbivory activity of latexes were triterpenoids and steroids. However, the activity could not be attributed to any single terpenoid. This discrepancy and the reduction of the latex activity after fractionation suggested a complementary effect of the compounds when in a mixture as represented by the latex. Additionally, aqueous fractions of several latexes were found to possess simple spectra, even with only 1 metabolite. These metabolites were determined to be organic acids that might be involved in the modulation of the rate of latex coagulation, potentially increasing the sealing and trapping effects of the latex.
Article
Full-text available
Some 170 years ago Piet Windvogel told William Atherstone about two plant-based arrow poisons prepared and used by Khoe-San living west of the Great Kei River in the modern-day Eastern Cape interior of South Africa. Atherstone’s interest in botany and in indigenous knowledge of local plant species fed into colonial intellectual networks, as well as imperialist concerns with scientific and/or economic profit. Yet his diarised record of Windvogel’s accounts has prompted us to compile a list of potential arrow poisons for a region where such ethnohistorical information is comparatively sparse. We have narrowed these down to the most likely botanical species used in Windvogel’s poison recipes: Prunus africana or rooistinkhout for the manufacture of t’ghee poison and perhaps Euphorbia mauritanica or gifmelkbos for taah poison, although species such as Acokanthera oppositifolia or gifboom, Asclepias fruticosa or melkbos and Carissa macrocarpa or the grootnoem-noem also merit consideration.
Chapter
Latexes of different plants contain a mixture of molecules which exhibit diverse activities against invaders. Among many other functions, they protect plants against herbivores, insects, fungi, parasites, bacteria and viruses. Due to the presence of pharmacologically active substances, mankind for centuries have applied latices and their preparations for their beneficial effect on human health. Most of these substances exert analgesic, wound healing, anti-pathogenic (antiviral and antimicrobial), anti-parasitic, anti-diabetic and other activities, which have been broadly exploited in traditional medicine. Following volume 93, this review presents popular latex applications and discusses perspectives for their use in medicine, agriculture and industry.
Chapter
Calotropis procera has an important biological role in controlling pests and disease-spreading vectors. A search for biopesticide is a novel approach for reducing the risk and persistence of chemical and synthetic pesticides. Different parts of plants such as leaves, bark, roots, flowers, seeds, etc. are extensively studied by numerous authors for insecticidal properties; however, the outcomes are not available in compiled form. Efforts are done to compile the research done on its insecticidal properties in the past 20 years. The available data has been classified based on target insect taxonomical orders, plant part with details of different fractions of extract, their activity, insecticidal activity, dosage, and extent of lethality. Preliminary data on larvicidal, insecticidal, adulticidal, and LC50 were retrieved along with plant parts, solvent/solvent fraction detail, and insect details (taxonomical order, larva/adult, and stage of larva). Later the data was classified for each plant part extracted in each solvent/fraction with taxonomical order of insect, the dosage used, the lethality of the dosage, and author details.
Article
Full-text available
Neofusiccocum batangarum is the causal agent of scabby canker of cactus pear (Opuntia ficus-indica L.). The symptoms of this disease are characterized by crusty, perennial cankers, with a leathery, brown halo. Characteristically, a viscous polysaccharide exudate, caking on contact with air, leaks from cankers and forms strips or cerebriform masses on the surface of cactus pear cladodes. When this polysaccharide mass was partial purified, surprisingly, generated a gel. The TLC analysis and the HPLC profile of methyl 2-(polyhydroxyalkyl)-3-(o-tolylthiocarbomoyl)-thiazolidine-4R-carboxylates obtained from the mixture of monosaccharides produced by acid hydrolysis of the three EPSs examined in this research work [the polysaccharide component of the exudate (EPSC) and the EPSs extracted from asymptomatic (EPSH) and symptomatic (EPSD) cladodes] showed the presence of d-galactose, l-rhamnose, and d-glucose in a 1:1:0.5 ratio in EPSC while d-galactose, l-rhamnose, d-glucose, and d-xylose at the same ratio were observed in EPSH and EPSD. The presence of uronic acid residues in EPSC was also showed by solid state NMR and IR investigation. Furthermore, this manuscript reports the chemical-physical characterization of the gel produced by the infected cactus pear.
Article
This study evaluated the growth characteristics of six guayule (Parthenium argentatum Gray) accessions irrigated with waters high in boron, selenium, and calcium and sodium salts under greenhouse conditions. The synthetic irrigation waters used in this investigation mimic the water quality used frequently for irrigation in the westside of the San Joaquin Valley, California, U.S.A. Guayule is a natural rubber-producing industrial crop that is tolerant of marginal soils and drought, and it may be grown as an alternative crop with poor quality waters for this region. Among the six accessions investigated for 55 days, three of them showed increased natural rubber concentration when grown under saline irrigation conditions compared to a non-saline irrigation (control). Elemental analysis in the leaves revealed that guayule can also absorb and accumulate potentially toxic elements. Results from this study suggest that specific accessions of guayule can be grown under saline irrigation conditions. Guayule exhibited potential bioremediation benefits under agronomic conditions found in the westside of the San Joaquin Valley, CA.
Thesis
Les métabolites de type diterpène produits par les espèces du genre Euphorbia sont remarquables aussi bien par la diversité de leur squelette carboné, qu’en raison de leurs multiples propriétés biologiques. Les travaux précédents, réalisés dans le cadre d’une collaboration entre le laboratoire des métabolites de plantes et micro-organismes associés (Institut de Chimie des Substances Naturels) et le laboratoire de chimie des produits naturels (Université de Corse), ont permis de mettre en évidence l’activité antivirale, notamment inhibitrice de la réplication du virus du chikungunya (CHIKV), d’extraits obtenus à partir d’espèces du genre Euphorbia poussant à l’état spontané en Corse. Dans ce contexte, l’objectif principal du présent travail de doctorat est la découverte de nouveaux composés diterpéniques, possédant une activité anti-CHIKV et/ou modulatrice de la résistance aux médicaments (anti-MDR). Afin de créer de la diversité chimique et d’augmenter leurs potentialités thérapeutiques, des essais de modifications structurales de molécules isolées ont été envisagés.Les travaux réalisés sur le latex d’Euphorbia dendroides ont permis d’isoler 24 esters de diterpène, dont 15 nouvelles molécules. Parmi eux, les esters de déoxyphorbol, isolés par l’utilisation de la prédiction de la bioactivité dans les réseaux moléculaires, ont montré une forte activité anti-CHIKV, tandis que deux esters de jatrophane ont inhibé les récepteurs transmembranaires de Candida albicans impliqués dans le phénomène de résistance médicamenteuse. Par ailleurs, une dizaine de composés ont été isolés d’Euphorbia pithyusa dont un ester de didéoxyphorbol présentant un pouvoir anti-CHIKV. Une vingtaine d’esters de diterpène, de type myrsinane, prémyrsinane et phorbol ont été isolés à partir d’E. pithyusa subsp. cupanii, sous-espèce de la précédente. Une approche métabolomique par LC-MS/MS, basée sur l’utilisation de réseaux moléculaires et l’étude des voies de fragmentations, a été mise en oeuvre en vue de comparer la composition diterpénique de ces deux taxa. D’un point de vue chimiotaxonomique, cette méthodologie s’est avérée efficace pour les différencier, mettant en évidence une variabilité chimique intraspécifique. Enfin, des modifications chimiques ont été entreprises sur deux esters de jatrophane isolés en quantité suffisante à partir du latex d’E. dendroides, permettant ainsi la formation de six dérivés originaux.
Article
Cucurbits have been used as phloem research models for many decades because their exudates can be accessed with ease. However, cucurbit plants possess two distinct phloem systems known as the fascicular phloem (FP) and extrafascicular phloem (EFP). Therefore, the molecular composition and function of certain exudates can be misinterpreted due to their unclear origin. To characterize the anatomy and function of the different phloem systems more clearly, we generated specific antibodies against marker proteins (PP1 homologs) allowing the clear identification of the EFP at the organ, tissue and cellular levels by immunological staining. We also used detailed microscopy to determine common and unique anatomical features of the FP and EFP sieve elements (SEs) in cucumber (Cucumis sativus). The comparison of exudation rates and the dynamic viscosity, density and sugar content of the exudates from plants grown in the light and dark revealed the consistent composition and behavior of the EFP exudate even when photosynthesis was prevented, thus differing from the properties of the FP exudate. Furthermore, the analysis of phloem transport using a fluorescein disodium salt showed only wound-induced exudation of dye from the EFP, indicating the absence of transport in this tissue. Our results show that it is important to distinguish between the EFP and FP in cucurbits, particularly their differing behaviors in response to wounding.
Chapter
All organisms must acquire energy in order to concentrate resources required to sustain life. Insects, like other animals, must acquire their energy and material resources from other organisms, living or dead. As a group, insects exploit a wide range of resources, including plant, animal, and detrital material, but individual organisms must find and acquire more specific resources that often do not provide required nutrients in proper balances or are physically or chemically defended. Therefore insects must be adapted physiologically and behaviorally to find suitable resources that vary widely in nutritional value, acceptability, and availability, depending on environmental conditions. Adaptations by individual species represent trade-offs among alternative strategies, thereby restricting the range of resources that can be exploited.
Article
Full-text available
The present article explains the effect of plant latex and its formulations on termite control. Latex is natural plant polymer secreted by highly specialized cells known as laticifers. It is a milky white thick complex mixture of proteins, alkaloids, starch, sugars, oils, tannins, resins, and gums. Both latex and its components show multiple deleterious effects such as toxic, antifeedant, and repellent activities. These effectively inhibit growth and reproductive behavior in number of insect species. Latex components delay egg maturation, development, and inhibit gonad development in termites. Latex constituents display contact and systemic action and primarily used as poison baits to control soil termite. Latex-based combinatorial anti-termite formulations could be used in spray for termite control. The usage is safer than synthetic chemicals and will minimize the risk of poisoning of food chain, soil, and aqueous environment. This review article suggests the use of slow release of latex components inside soil when applied as poison baits for control of field termites.
Article
In this review article an effort has been made to provide basic knowledge about plant latex. In this paper the origin and evolutionary aspects of latex has been mentioned. The geographical distribution and classification along with the physical and anatomical traits have also been brought into limelight. Moreover, the presence of phytochemicals, proteins and variation of the content of rubber in latex has been referred in the paper respectively. This paper would be of great help in gaining deeper knowledge about the plant latex for future researches.
Chapter
Maintenance of nutritional quality in crops is vital to provide quality human food as well as animal feed under stressful environmental conditions. The aim of the present review is to assess the effects of heat stress on qualitative traits of field crops. Environmental stresses significantly affect the nutritional properties and quality traits of crops through physiological and biochemical alterations occurring at different growth stages. Among environmental stresses, heat stress is the most pertinent especially under the current changing climate. Heat stress generally affects the grain quality depending upon crop cultivars. Several studies have proposed different management approaches for enhancing the grain quality of crops under heat stress environments. For managing heat stress, the grain quality may serve as a critical parameter for discriminating the crop genotypes having a higher potential to grow under heat stress conditions. Among heat stress mitigating strategies, seed priming and application of osmoprotectants, organic acids, and other antioxidants have the potential to increase the grain quality of many field crops.
Chapter
Legumes are grown in more than 120 countries across all the continents. 90% of the global production of legume are produced in small group of countries such as India, Turkey, Pakistan, Bangladesh, Nepal, Iran, Mexico, Myanmar, Ethiopia, Australia, Spain, Canada, Syria, Morocco and Egypt. Legume are vegetarian sources of proteins and are an integral part of daily diet in several forms universally. Legume crops are great worth crops and play a dynamic role in crop diversification and economic sustainability of legume farming systems in dry areas. Most of the legume crops are grown under rainfed agroecosystem with poor level of input use which has resulted in low production. In this chapter we focus on (i) ecology and adaptation of legumes crop (ii)physiological responses of grain legumes to stress environments (ii) agronomic approaches to stress management.
Chapter
Current trends in population growth suggest that global food production is unlikely to meet future demands under projected climate change scenarios unless the pace of plant improvement is accelerated. Plant production is facing many challenges due to changing environmental conditions and the growing demand for new plant-derived materials. These challenges come at a time when plant science is making significant progress in understanding the basic processes of plant growth and development. Major abiotic stresses like drought, heat, cold and salinity often cause a range of morphological, physiological, biochemical , and molecular changes affecting plant growth, development, and productivity; so sustainable food production poses a serious challenge to much of the world, particularly in emerging countries. This underscores the urgent need to find better ways to translate new advances in plant science into concrete successes in agricultural production. In order to overcome the negative effects of abiotic stress and to maintain food security in the face of these challenges, new, improved, and resilient plant varieties, contemporary breeding techniques, and a deep understanding of the mechanisms for offsetting harmful climate change are undoubtedly necessary. In this context, Improvement of Plant Production in the Era of Climate Change is a guide to the most advanced techniques that help in understanding plant response to abiotic stress, leading to new horizons and the strategy for the current translation studies application to overall solution to create a powerful production and crop improvement in such an adverse environment. FEATURES • Provides a state-of-the-art description of the physiological, biochemical, and molecular-level understanding of abiotic stress in plants. • Courses taught in universities from basics to advanced level in field of plant physiology, molecular genetics, and bioinformatics will use this book. • Focuses on climatic extremes and their management for plant protection and production, which is great threat to future generation and food security. • Understanding of new techniques pointed out in this book will open the possibility of genetic engineering in crop plants with the concomitant improved stress tolerance. • Addressing factors that are threatening future food production and providing potential solutions to these factors. • Written by a diverse group of internationally famed scholars, this book adds new horizons in the field of abiotic stress tolerance.
Article
Ethnopharmacological relevance In folk medicine, parts of Plumeria alba L. are used for treatment of many diseases, with its latex being used for curing skin diseases and promoting wound healing. Aim of the study This study aimed to study the role of P. alba L. latex in hemostasis and platelet aggregation. Materials and Methods The latex of P. alba L. was processed to remove waxes and enrich protein content, and the final extract was named Plumeria alba L. natant latex (PaNL). PaNL was analyzed for protease activity against casein. The type of protease in PaNL was identified by using protease inhibitors such as E–64, phenylmethylsulfonyl fluoride, ethylenediaminetetraacetic acid, and pepstatin A. Human fibrinogen, fibrin, and collagen types I and IV were subjected to hydrolysis with different concentrations of PaNL. The thrombin–like activity of PaNL was determined by analyzing its fibrinogen–clotting and procoagulant activities. The role of PaNL in platelet aggregation was also investigated. Its hemorrhagic and edema–inducing activities were evaluated in a mouse model. Phytochemical compounds were identified by gas chromatography – mass spectroscopy. Results The findings of casein/gelatin zymography confirmed that PaNL possesses protease activity. The results of the protease inhibition study indicated the presence of a cysteine–type protease(s) in PaNL. PaNL hydrolyzed the subunits of fibrinogen, fibrin, and collagen types I and IV. Its fibrin–degradation activity indicated that PaNL possesses plasmin–like activity. PaNL induced clotting of citrated human plasma within 3 min of incubation in the absence of CaCl2, indicating the presence of thrombin–like activity, which was further confirmed by the results of the fibrinogen–clotting assay. PaNL induced platelet aggregation in the absence of agonists. There was no hemolytic activity. Mice injected with PaNL did not show edema, or hemorrhagic activity. Conclusion PaNL possesses procoagulant, fibrino(geno)lytic, thrombin– and plasmin–like activities and induces platelet aggregation, which could explain its usage for wound treatment in folk medicine.
Article
Full-text available
Wounding leaves or stems of Lactucaspecies releases a milky latex onto the plant surface. We have examined the constituents of latex from Lactuca sativa (lettuce) cv. Diana. The major components were shown to be novel 15-oxalyl and 8-sulfate conjugates of the guaianolide sesquiterpene lactones, lactucin, deoxylactucin, and lactucopicrin. The oxalates were unstable, reverting to the parent sesquiterpene lactone on hydrolysis. Oxalyl derivatives have been reported rarely from natural sources. The sulfates were stable and are the first reported sesquiterpene sulfates from plants. Unusual tannins based on 4-hydroxyphenylacetyl conjugates of glucose were also identified. Significant qualitative and quantitative variation was found in sesquiterpene lactone profiles in different lettuce varieties and in other Lactuca spp. The proportions of each conjugate in latex also changed depending on the stage of plant development. A similar profile was found in chicory, in which oxalyl conjugates were identified, but the 8-sulfate conjugates were notably absent. The presence of the constitutive sesquiterpene lactones was not correlated with resistance to pathogens but may have a significant bearing on the molecular basis of the bitter taste of lettuce and related species. The induced sesquiterpene lactone phytoalexin, lettucenin A, was found in the Lactuca spp. but not in chicory.
Article
Full-text available
Using in situ RNA hybridization and immunohistochemical techniques, we investigated the tissue-specific and light-dependent expression of four genes involved in phenylpropanoid metabolism in various parts o f parsley ( Petroselinum crispum) seedlings.The genes encode phenylalanine amm onia-lyase (PAL) and 4-coum arate: Co A ligase (4 CL), two enzymes of general phenylpropanoid metabolism; chalcone synthase (CHS), the keyenzyme of flavonoid biosynthesis; and bergaptol O-methyltransferase (BMT), a late enzyme of the furanocoumarin pathway. In young leaves, PAL and 4 CL genes were expressed predominantly and in a coordinated fashion in epidermal cells, young xylem cells of vascularbundles, and epithelial cells of oil ducts. The gene(s) encoding BMT wasactive exclusively in the epithelial cells of oil ducts, where as CHS gene expression was largely confined to the epidermis. In shoot and root apices, PAL, 4 CL and CHS m R N A s were detectable at low levels without distinct patterns. The corresponding proteins, however, accumulated preferentially in the protoderm and pith meristem of the shoot apex and in root-cap cells. A gene encoding pathogenesis-related protein 1 (PR 1)was analyzed in rootsfor comparison and was found to be expressed predominantly in the cortical cells o f root tips. The expression o f all genes investigated was, to a greater or lesser extent, dependent on light conditions and tissue age, with highest levels occurring in newly differentiated, light-exposed tissue. In the leaf epidermis o f seedlings illuminated for 20 h, PAL and CHS m R N A s and proteins, as well as 4 CL protein, were particularly abundant. © 2009 Walter de Gruyter.
Article
Full-text available
A revised and updated classification for the families of flowering plants is provided. Many recent studies have yielded increasingly detailed evidence for the positions of formerly unplaced families, resulting in a number of newly adopted orders, including Amborellales, Berberidopsidales, Bruniales, Buxales, Chloranthales, Escalloniales, Huerteales, Nymphaeales, Paracryphiales, Petrosaviales, Picramniales, Trochodendrales, Vitales and Zygophyllales. A number of previously unplaced genera and families are included here in orders, greatly reducing the number of unplaced taxa; these include Hydatellaceae (Nymphaeales), Haptanthaceae (Buxales), Peridiscaceae (Saxifragales), Huaceae (Oxalidales), Centroplacaceae and Rafflesiaceae (both Malpighiales), Aphloiaceae, Geissolomataceae and Strasburgeriaceae (all Crossosomatales), Picramniaceae (Picramniales), Dipentodontaceae and Gerrardinaceae (both Huerteales), Cytinaceae (Malvales), Balanophoraceae (Santalales), Mitrastemonaceae (Ericales) and Boraginaceae (now at least known to be a member of lamiid clade). Newly segregated families for genera previously understood to be in other APG-recognized families include Petermanniaceae (Liliales), Calophyllaceae (Malpighiales), Capparaceae and Cleomaceae (both Brassicales), Schoepfiaceae (Santalales), Anacampserotaceae, Limeaceae, Lophiocarpaceae, Montiaceae and Talinaceae (all Caryophyllales) and Linderniaceae and Thomandersiaceae (both Lamiales). Use of bracketed families is abandoned because of its unpopularity, and in most cases the broader circumscriptions are retained; these include Amaryllidaceae, Asparagaceace and Xanthorrheaceae (all Asparagales), Passifloraceae (Malpighiales), Primulaceae (Ericales) and several other smaller families. Separate papers in this same volume deal with a new linear order for APG, subfamilial names that can be used for more accurate communication in Amaryllidaceae s.l., Asparagaceace s.l. and Xanthorrheaceae s.l. (all Asparagales) and a formal supraordinal classification for the flowering plants.
Article
Full-text available
Ehrlich and Raven's postulate that rapid diversification follows innovation in plant defense has often been invoked a posteriori for plant lineages of unusual diversity and chemical distinctiveness. The postulate can be more rigorously tested by defining a novel class of defense using chemical and/or anatomical criteria, independent of taxonomic lineage. If multiple plant lineages have evolved the new defense type, then according to the postulate they should be consistently more diverse than their sister groups (of equal age, by definition) when the latter retain the primitive defensive repertoire. Secretory canals are an independently defined, repeatedly evolved feature that functions to protect plants from herbivores and pathogens. The canals might therefore be expected to allow plant radiation in an adaptive zone of reduced herbivory and disease. We have quantified the evidence for this hypothesis by comparing the diversities of lineages that have independently evolved canal systems with their sister groups for as many plant lineages as current taxonomic evidence allows. A sign test showed that canal-bearing lineages have consistently higher diversities than their sister groups (P = .0021). Explanations for this result, other than selective advantage conferred by secretory canals, are examined and provisionally rejected.
Article
Full-text available
The leaves of the privet tree, Ligustrum obtusifolium (Oleaceae), retain a strong lysine-decreasing activity caused by enzymatically-activated oleuropein, an iridoid glycoside. Protein treated with this activity become innutritive to insects because of the loss of lysine. We previously found that several privet specialist caterpillars secrete high concentrations of glycine in their digestive juices. Previous in vitro experiments showed that glycine inhibits lysine-decreasing activity of oleuropein. Therefore, we hypothesized that the lysine-decreasing activity acts to defend privet tree against herbivores and that glycine secretion by insects is an adaptive trait to counter the privet defense. In the present study, we aimed to examine whether these assumptions hold true under physiological conditions, and performed in vivo bioassays and physiological analyses using the Eri silkworm, Samia ricini (Saturniidae), a non-privet specialist. Significant decreases in larval growth and lysine concentration in the midgut lumen were observed when larvae were fed intact privet leaves compared to when they were fed heat inactivated privet leaves. These decreases were inhibited when larvae were fed intact privet leaves together with glycine, indicating that the privet defense with oleuropein and the specialist adaptation with glycine do function under physiological conditions. This study thus provides a rare view into the detailed physiological impacts of anti-nutritive plant defense and insect physiological adaptation in vivo.
Article
Full-text available
This study describes the digestive protease activity extracted from the gut of fifth-instar Monarch butterfly larvae, and its proteolytic activity on latex proteins of their host plant, Calotropis procera (the milkweed) and related non-host species from the milkweed family. Gut extracts digested azocasein, BANA and BApNA. Cysteine protease inhibitors such as E-64 and iodoacetamide inhibited proteolytic activity on azocasein; however, the serine protease inhibitors PMSF and leupeptin were more effective. Gut extracts promptly digested LP and were not affected by endogenous latex proteases. Gut extracts, however, did not digest LP from Cryptostegia grandiflora and only slightly digested LP from Plumeria rubra, two plant species that are not consumed by Monarch larvae. The protein profiles of latex proteins extracted from healthy and attacked plants were different. A protein identified as glycoside hydrolase was detected in increased concentrations in latex from damaged plants. Larvae fed on artificial diets containing 1% or 5% latex proteins were not adversely affected and gained weight faster than control larvae. These results provide new information on the resistance of Monarch larvae fed on C. procera and suggest that the ability of Monarch proteolytic enzymes to promptly digest LP can explain (at least in part) how these insects overcome the defensive proteins found in C. procera latex.
Article
Full-text available
Latex is actively secreted on wounded unripe fruits from Caricapapaya. We describe the changes in peptide composition by SDS-PAGE analysis of latex from C.papaya collected at various times after incision of the unripe fruit. Non random changes in the relative amount of several peptides occur during latex coagulation. The measurement of amidase activity of coagulating latex shows three peaks of activity between 2 and 1200 s. The major activity is found at 1000 s, which is when coagulation is under way. The data from in situ proteolytic activity experiments confirm the presence of active enzyme(s) when latex begins to flow from damaged fruits.
Article
Full-text available
Many plants contain carbohydrate-binding proteins that are commonly designated as lectins, agglutinins, or hemagglutinins. Due to the obvious differences in molecular structure, biochemical properties, and carbohydrate-binding specificity, plant lectins are usually considered a complex and heterogeneous group of proteins. Recent advances in the structural analysis of lectins and molecular cloning of lectin genes enable subdividision of plant lectins in a limited number of subgroups of structurally and evolutionary related proteins. Four major lectin families, namely, the legume lectins, the chitin-binding lectins composed of hevein domains, the type 2 ribosome-inactivating proteins, and the monocot mannose-binding lectins comprise the majority of all currently known plant lectins. In addition to these four large families the jacalin-related lectins, the amaranthin family, and the Cucurbitaceae phloem lectins are now recognized as separate subgroups. Each of the above-mentioned lectin families is discussed in detail. The description of the individual lectin families includes (1) a brief historical note, (2) an overview of the occurrence, molecular structure, and primary structure of the lectins, (3) a detailed discussion of the structure of the gene(s) and the biosynthesis and posttranslational processing of the primary translation products, (4) a summary of carbohydrate-binding specificity, (5) if relevant a note on the occurrence of lectin-related proteins, (6) a description of the three-dimensional structure of the lectins and the protomers, (7) a detailed discussion of the molecular evolution, and (8) a critical assessment of the physiological role of each group of lectins. Lectins that cannot be classified into one of the seven groups are discussed separately. General conclusions about the structure, evolution, and function of plant lectins are summarized in the concluding remarks.
Article
Full-text available
Methanol extracts of vine latex of four cultivars of sweetpotato [Ipomoea batatas (L.) Lam.] were analyzed for their chemical phenolic composition by reversed-phase HPLC. Major components were identified as hexadecyl, octadecyl, and eicosyl p-coumarates by an evaluation of data from UV spectra, hydrolysis, synthesis, and GC/MS of their trimethylsilyl derivatives. Both Z- and E-isomers of the phenolic acid were found, with the latter predominating. Trace quantities of hexadecyl (Z)- and (E)-ferulates were also identified in ester concentrates. Levels of octadecyl (E)-p-coumarate ranged from 0.7% fresh weight in cv. Resisto to almost 2% in cv. Jewel, while the hexadecyl ester levels were only 1/4 to 1/3 these values. Levels of the Z-esters were 1/10 to 1/20 of the levels of the corresponding E-isomers. Levels of the esters in cv. Jewel sweetpotato root latex were 2-10-fold the levels in the vine latex, while the ratio of E-esters to Z-esters was found to be 7-14-fold. The concentration of Z-esters among the sweetpotato cultivars tested correlated closely with the leaf feeding index for the sweetpotato weevil (Cylas formicarius) (R(2): C-20 = 0.96; C-18 = 0.98; C-16 = 0.71). The results indicate a possible relationship between latex chemistry and insect resistance that might be exploited via plant breeding.
Article
Full-text available
Latex is a sticky emulsion that exudes upon damage from specialized canals in about 10% of flowering plant species. Latex has no known primary metabolic function and has been strongly implicated in defense against herbivorous in-sects. Here we review historical hypotheses about the function of latex, evi-dence that it serves as a potent defense, and the chemistry and mode of action of the major constituent defense chemicals and proteins across a diversity of plant species. We further attempt to synthesize the characteristics of latex as a coordinated plant defense system. Herbivores that feed on latex-bearing plants typically evade contact with latex by severing the laticifers or feeding intercellularly, or may possess physiological adaptations. Convergent evolu-tion appears to be rampant both in plants with latex and insects that exploit latex-bearing plants. Because latex shows phenotypic plasticity, heritability, and macoevolutionary lability, it is an ideal system to study plant-herbivore interactions using evolutionary approaches.
Chapter
Midgut and body tissues of caterpillars of the black swallowtail butterfly (Papilio polyxenes Fabr.) possess high enzymatic activity that catalyzes the detoxification of linear furanocoumarins, thus explaining the tolerance of P. polyxenes to these phototoxins. Observations from nature indicate that P. polyxenes caterpillars are less tolerant toward the presence of angular furanocoumarins in potential host plants, and our studies with a commonly occurring angular furanocoumarin suggest that metabolic detoxification of such compounds by P. polyxenes occurs at a relatively slower rate than with the linear analogs. The capacity to detoxify dietary furanocoumarins is a major determinant of host plant acceptability by P. polyxenes; furthermore, this phenomenon represents a clear example of herbivore circumvention of a normally effective host-plant-resistance mechanism.
Chapter
Plants deploy an arsenal of chemical defences against invading herbivores (e.g. Rosenthal and Berenbaum, 1991). Although hundreds of natural products have been characterized, the mode of actions is known for only a few. Our focus is on ‘antinutrients’, a term that has been used in the entomological literature without sufficient definition. Anti-nutrients diminish nutrient bioavailability by chemically modifying the nutrient, forming less active complexes with the nutrient, or by hindering digestion, absorption or utilization of the nutrient. Defining criteria for an antinutrient are (1) the symptoms produced by the antinutrient resemble those caused by insufficiency of a given nutrient and (2) nutrient treatment alleviates the effect of the antinutrient.
Article
;Two rubber particle protein genes and one latex gene in fig tree (Ficus carica) have been isolated and their expression following various abiotic stress treatments have been investigated. The two major proteins that are tightly associated with the catalytically active rubber particles have been sequenced to be peroxidase (POX) and trypsin inhibitor (TRI). A cDNA encoding a basic class I chitinase (CHI) has also been isolated from the fig tree latex. Wounding treatment strongly induced the expression of the three stress-related genes. Among the abiotic stresses investigated, drought treatment greatly induced the expression of POX, whereas the expression of CHI and TRI decreased after the same treatment. Cold treatment reduced slightly the transcript levels of the thee genes, and NaCl reduced marginally the expression of CHI. The expression of POX, CHI, and TRI was induced by jasmonic acid and abscisic acid, by jasmonic acid, and by salicylic acid, respectively. Different expression of the stress-related genes following various abiotic stress or plant hormone treatments suggests that a crosstalk exists between the signal transduction pathways elicited by abiotic stresses and hormones in plants. Our present results showing the expression of stress-related proteins on the surface of rubber particles and latex in F. carica also imply the possible role of rubber particles and latex in defense in rubber-producing plant species.
Article
Plants respond to insect feeding with a number of defense mechanisms. Using maize genotypes derived from Antiquan germ plasm that are resistant to Lepidoptera, we have demonstrated that a unique 33-kD cysteine proteinase accumulates in the whorl in response to larval feeding. The abundance of the proteinase increased dramatically at the site of larval feeding after 1 hr of infestation and continued to accumulate for as long as 7 days. The 33-kD cysteine proteinase was most abundant in the yellow-green portion of the whorl—the normal site of larval feeding and the tissue that has the greatest inhibitory effect on larval growth in bioassays. The proteinase was expressed in response to wounding and was found in senescent leaves. It may be a marker of programmed cell death. The gene coding for the proteinase, mir1, has been transformed into Black Mexican Sweet callus. When larvae were reared on callus expressing the proteinase, their growth was inhibited ∼60 to 80%. The expression of a cysteine proteinase, instead of a cysteine proteinase inhibitor, may be a novel insect defense mechanism in plants.
Article
To determine if the arrangement of secretory canals in leaves affects foraging by folivorous insects, we examined the behaviors of 33 species found on diverse canal-bearing plants. Insect behaviors were categorized into three principal classes: vein cutting, trenching, and neither behavior. Canal architectures were ascertained by damaging leaves with standardized tests and measuring the secretory response Our observations document a precise correspondence between herbivore behavior and canal morphology. Vein-cutting insects occur on plants with arborescent canals (resin canals in Anacardiaceae and nonarticulated laticifers in Apocynaceae, Asclepiadaceae, and Moraceae). By severing the secretory canals in leaf veins, insects prevent the flow of secretion to distal branches of the canals. Trenching insects, in contrast, are found on plants with net-like canal systems (anastomosing articulated laticifers in Asteraceae and Caricaceae, and exuding phloem in Cucurbitaceae). To eliminate secretion outflow from these plants, the insects must transect all strands of the network by cutting a trench. The secretory canals of the Convolvulaceae (nonanastomosing articulated laticifers) differ from the preceding categories in being restricted primarily to the major leaf veins. The behavior of herbivores on this family is also distinct: all feed between the major veins without prior vein cutting or trenching. Thus, insects employ the same behavior on similar canal architectures, even when their host plants otherwise differ in taxonomy, secondary chemistry, and canal type. The occurrence of vein-cutting and trenching behaviors in multiple lineages of insects that include caterpillars, beetles, and katydids indicates that the behaviors have evolved repeatedly, apparently through convergence. Our comparative analysis supports the view that these preingestive behaviors function specifically to deactivate defensive canal systems.
Article
:Using in situ RNA/RNA hybridization, enzyme immunolocalization, and histochemical techniques, several phenylpropanoid biosynthetic activities and products were localized in tissue sections from various aerial parts of parsley (Petroselinum crispum) plants at different developmental stages. The enzymes and corresponding mRNAs analyzed included two representatives of general phenylpropanoid metabolism: phenylalanine ammonia-lyase (PAL) and 4-coumarate: CoA ligase (4CL), and one representative each from two distinct branch pathways: chalcone synthase (CHS; flavonoids) and S-adenosyl-L-methionine: bergaptol O-methyltransferase (BMT; furanocoumarins). In almost all cases, the relative timing of accumulation differed greatly for mRNA and protein and indicated short expression periods and short half-lives for all mRNAs as compared to the proteins. PAL and 4CL occurred almost ubiquitously in cell type-specific patterns, and their mRNAs and proteins were always coordinately expressed, whereas the cell type-specific localization of flavonoid and furanocoumarin biosynthetic activities was to a large extent mutually exclusive. However, the distribution patterns of CHS and BMT, when superimposed, closely matched those of PAL and 4CL in nearly all tissues analysed, suggesting that the flavonoid and furanocoumarin pathways together consituted a large majority of the total phenylpropanoid biosynthetic activity. Differential sites of synthesis and accumulation indicating intercellular translocation were observed both for flavonoids and for furanocoumarins in oil ducts and the surrounding tissue. The widespread occurrence of both classes of compounds, as well as selected, pathway-specific mRNAs and enzymes, in many cell types of all parsley organs including various flower parts suggests additional functions beyond the previously established roles of flavonoids in UV protection and furanocoumarins in pathogen defence.
Article
To test if secretory canals limit the host ranges of polyphagous moth larvae, we measured the growth of Trichoplusia ni (cabbage looper) and Spodoptera ornithogalli (yellow-striped armyworm) on plants in nine families, including species with and without secretory canals. Larvae were reared to the final instar on excised leaves of the test plant, weighed, then enclosed in the field on either detached leaves with depressurized canals or intact leaves with undamaged canals. After 24 h, the larvae were reweighed and the leaves were examined for evidence of trenching. For comparison, nine additional species of generalist caterpillars were tested on Lactuca serriola (with latex canals) using the same procedure; five of these species were also tested with Petroselinum crispum, which has resin canals.
Article
The Monarch butterfly (Danaus plexippus) sequesters cardiac glycosides (CG) for its chemical defense against predators. Larvae and adults of this butterfly are insensitive towards dietary cardiac glycosides, whereas other Lepidoptera are sensitive and intoxicated by ouabain. Ouabain inhibits Na(+),K(+)-ATPase by binding to its α-subunit. We have amplified and cloned the DNA-sequence encoding the respective ouabain binding site. Instead of the amino acid asparagine at position 122 in ouabain-sensitive insects, the Monarch has a histidine in the putative ouabain binding site, which consists of 12 amino acids. Starting with the CG-sensitive Na(+),K(+)-ATPase gene fromDrosophila, we converted pos. 122 to a histidine residue as inDanaus plexippus by site-directed mutagenesis. Human embryonic kidney cells (HEK) (which are sensitive to ouabain) were transfected with the mutated Na(+),K(+)-ATPase gene in a pSVDF-expression vector and showed a transient expression of the mutatedDrosophila Na(+),K(+)-ATPase. When treated with ouabain, the transfected cells tolerated ouabain at a concentration of 50 mM, whereas untransformed controls or controls transfected with the unmutatedDrosophila gene, showed a substantial mortality. This result implies that the asparagine to histidine exchange contributes to ouabain insensitivity in the Monarch. In two other CG-sequestering insects, e.g.,Danaus gilippus andSyntomeida epilais, the pattern of amino acid substitution differed, indicating that the Monarch has acquired this mutation independently during evolution.
Article
Five phosphatases were isolated from the latices of three members of the Euphorbiaceae. From Euphorbia lathyris were obtained phosphatases 11 and 12; from E. trigona phosphatase t and from Elaeophorbia drupifera the enzymes d1 and d2. Phosphatases 11, 12 and t were purified to homogeneity. Amino acid compositions are reported and other properties of the enzymes are described. The two enzymes described from E. lathyris both have two pH maxima d(11 at 5.0 and 6.8,12 at 5.8 and 7.5) while t, d1 and d2 respectively have maxima at pHs of 5.6,5.6 and 5.0. On the basis of their responses to several residue-specific inhibitors the five phosphatases apparently comprise three groups: 12 and d1, t and d2, and 11.
Article
Amounts of the sesquiterpene lactones and the major phenolics were determined in the chicory plant at different times during the growing season. The levels of the sesquiterpene lactones (lactucin, lactupicrin and 8-deoxylactucin) and the hydroxycoumarin cichoriin were found to be highest in the most actively growing regions of the plant. In two-choice and no-choice feeding experiments with borosilicate discs, 8-deoxylactucin, lactupicrin and cichoriin significantly reduced feeding of Schistocerca gregaria at levels comparable to those present in the plant. Cichoriin was still significantly antifeedant at 0.006% dry wt, while aesculin, aesculetin and the caffeic acid ester, chicoric acid were inactive. We conclude that the three sesquiterpene lactones secreted in the latex provide a significant barrier to herbivory in chicory, although the phenolics and notably cichoriin also protect the plant from insect feeding.
Article
The alkaloid content in Chelidonium majus has been examined during the day, both in summer and in winter. Sanguinarine, chelidonine, chelerythrine, berberine and coptisine were detected in all parts of the plant. While the berberine content was rather stable, the other alkaloids undergo remarkable daily variations probably due to the combined effect of light and temperature.
Article
Latex-producing plants are widespread in different habitats. Usually these plants secrete an endogenous milk-like fluid in a network of laticifer cells in which sub-cellular organelles intensively synthesize proteins and secondary metabolites. The biological importance of latexes is still unclear and accumulated evidences of their physiological role are still limited. Here laticifer proteins (LP) from Calotropis procera were assayed for insecticidal action against different crop pests in attempt to give new insights for the biological role of latexes. Diets containing 4% LP affected survival (LD50=4.61%) and decreased weight gain (ED50=3.07%) of third instars Ceratitis capitata (Diptera: Tephritidae). Third instars Anticarsia gemmatalis (Lepidoptera: Noctuidae) fed on diets containing 0.1% (w/w) of LP showed reduced body mass while survival was reduced (LD50=0.48%) only for insects grown on 0.5% LP-containing diets. Nonetheless, 1% LP was ineffective against third instars Spodoptera frugiperda (Lepidoptera: Noctuidae). Diets containing 1% LP slightly diminished survival of Dysdercus peruvianus (Hemiptera: Pyrrhocoridae) nymphs while 2% LP was more effective with consistent reduction in bodyweight (ED50=1.4%) observed at the 14th day. Digestive enzymes of gut extracts of D. peruvianus were unable to breakdown LP. On the contrary, heat treated LP was capable of reducing by 50% proteolysis of gut extracts using BANA as substrate suggesting presence of inhibitory activity of cysteine proteinases. Adults of D. peruvianus were not affected when grown in diets containing 1% of LP. Laticifer proteins were shown to possess chitin-binding proteins and chitinolytic activity. Lectin activity was not detected. Occurrence of cysteine proteinase activity already reported in C. procera latex combined with the activities described here could explain, at least in part, the deleterious effects observed.
Article
Cardenolides, free sterols, triacylglycerols, triterpenyl acetates, steryl- and triterpene esters were the major lipid classes in the stem of five- to eight-week-old Asclepias curassavica plants, in which 30% of the cardenolides occurred in the latex. Excised defoliated stems incorporated up to 6.7% of radioactive acetate into these lipids in a three day incorporation period. The label from [2-14C]acetate proceeded mainly to the fatty acid moiety of the triterpene and steryl esters, the fatty acids of the triacylglycerols, the free sterols and the cardenolides. Optimal results were obtained with 10 cm stems from six-week-old plants. An increased supply of acetate (2.5–10 μmol stem−1) showed a saturated synthesis of cardenolides and triacylglycerols and caused an enhanced production of triterpenyl acetates. The highest yield of [14C]cardenolides was obtained after uptake of 5 μmol of acetate per stem. The cardenolide composition of the incubated stem tissue increased on the absorption of 10 μmol of acetate and major changes in organic acid composition were measured after uptake of 20 μmol of acetate. [13C]Uscharidin was biosynthesized from 0.5 mmol of [1,2-13C]acetate by 100 stem tips. 13C NMR spectroscopy showed an unequal relative enrichment in both the genin and the dideoxyhexosulose moiety. The construction of the butenolide ring by the condensation of a pregnane derivative with one molecule acetate as observed for 5β-cardenolides is not confirmed by these-NMR data.
Article
Crude latex sera from 17 members of the genus Euphorbia and from Elaeophorbia drupifera (Euphorbiaceae) contained a wide range of agglutinating abilities. Homogeneous lectins were isolated from latices of Euphorbia coerulescens, E. hermentiana, E. lactea, E. lactea cristata, E. lathyris, E. trigona and Elaeophorbia drupifera. The M,s of the lectins ranged from 60 to 67 000, and the unit weights from 27 to 38 000. pI measurements showed that each latex contained from five to 13 isolectins. The amino acid compositions of the seven lectins were determined: those from E. hermentiana, E. lactea, E. lactea cristata, E. trigona and Elaeophorbia drupifera are related.
Article
Hevains b and l, isolated respectively from the serum and lutoids of freeze-dried latex from Hevea brasiliensis, were purified to homogeneity and compared with hevain a from commercial, ammonia-treated latex. The Mrs of hevains a and b are 69 000 and 58 000, respectively, and both exist in several charged forms. The amino acid compositions of the two enzymes differ significantly, but the reactivities to a variety of ester and protein substrates are similar, as are the pH optima. Hevain l is a distinct protease of Mr 80 000 and unique amino acid composition. It displays esterolytic activity and will digest insulin B chain, but is not proteolytic to azocollagen, azocasein, bovine serum albumen or haemoglobin. The activities of all three enzymes are dependent on the presence of serine and histidine residues.
Article
Partial characterization of the crude proteolytic extracts of five Asclepiadaceae species namely Araujia hortorum Fourn., Asclepias curassavica L., Funastrum clausum (Jacq.) Schlechter, Morrenia brachystephana Griseb. and Morrenia odorata (Hook. et Arn.) Lindley, and a comparison of these results and those from other Asclepiadaceae species are reported. Additionally, the crude extract from M. brachystephana was submitted to further purification and characterization. The crude enzyme showed high proteolytic activity when assayed on casein in the presence of 12 mM cysteine but was strongly inhibited by very low concentrations of sodium iodoacetate (0.01 mM) and mercuric chloride (0.1 mM) suggesting that the enzyme belongs to the cysteinyl-proteases type. Fractioned acetone precipitation followed by cation exchange chromatography allowed the separation of two basic ( pI > 9.3) proteolytically active fractions, both homogeneous by sodium dodecyl sulphate–polyacrylamide gel electrophoresis and with similar molecular masses (25.5 and 26 kDa).Copyright © 1998 John Wiley & Sons, Ltd.
Article
The objective of the present work was to contribute to the understanding of the physiological role of latex lipolytic activity in Euphorbia characias. To this end, the acid and basic lipolytic activity of E. characias latex, as well as the substrate specificity on various triacylglycerols, were measured during the plant's vegetative and reproductive stages. Both activities appeared to increase during the reproductive stage and to peak at the beginning of the vegetative stage, when new leaves and branches are formed. For the first time, the phospholipolytic and esterase activity of E. characias latex is also reported. An extraction method in aqueous medium with the zwitterionic detergent CHAPS was successfully used to extract lipolytic activity from latex. Extraction permitted the selective recovery of a single protein spot, with a molecular weight of 37kDa, and presumably made of several acid isoforms which retained both lipolytic and phospholipolytic activity. The biochemical results suggest that lipolytic and phospholipolytic activity could depend on a single hydrolytic enzyme with several isoforms, equally expressed throughout the biological cycle of the plant. On the basis of the obtained results, we hypothesise that the E. characias latex lipase should be considered as an aspecific acylhydrolase with a combined lipase/phospholipase A activity.
Article
Neuronal tissues from Manduca sexta, the tobacco hornworm, Hyalophora cecropia, the silkmoth and Danaus plexippus, the Monarch Butterfly, contain Na+K+-ATPase which is sensitive to cardiac glycoside (ouabain). The Km for K+ stimulation of Na+K+-ATPase in M. sexta and D. plexippus is 2.2 mM and for Na+ stimulation in D. plexippus, 6.0 mM. In vitro ouabain concentrations of 1.0 × 10−5 M and 5.0 × 10−5 M in the presence of 7.5 mM K+ inhibited Na+K+-ATPase activity in H. cecropia and M. sexta by 50% respectively. Na+K+-ATPase from D. plexippus was approximately 300 times less sensitive. High concentrations (10−3 M in haemolymph) of ouabain had no effect on M. sexta in vivo. This is largely explained by haemolymph K+ (>; 30 mM) antagonizing the binding of ouabain to Na+K+-ATPase. As demonstrated in vitro, 30 mM K+ totally protects Na+K+-ATPase from inhibition by 7.5 × 10−3 M ouabain in D. plexippus and protects the enzyme by 65% in M. sexta. At least part of the physiological burden incurred in utilization of cardiac glycoside ingestion and storage for protection from predation, however, is probably related to the toxic effects of cardiac glycosides on neuronal Na+K+-ATPase.
Article
Summary Our paper addresses field survivorship of first instar monarch butterfly larvae (Danaus plexippus L., Lep.: Danainae) in relation to the dual cardenolide and latex chemical defenses of the sand hill milkweed plant,Asclepias humistrata (Asclepiadaceae) growing naturally in north central Florida. Survival of first instar larvae in the field was 11.5% in the first experiment (15–20 April 1990), and dropped to 3.4% in the second experiment (20–30 April). About 30% of the larvae were found glued to the leaf surface by the milkweed latex. Predator exclusion of non-flying inverte-brates by applying “tanglefoot” to the plant stems suggested that the balance of the mortality was due to volant inverte-brates, or to falling and/or moving off the plants. Regression analyses to isolate some of the other variables affecting survivorship indicated that first instar mortality was correlated with (1) increasing cardiac glycoside concentration of the leaves, (2) increasing age of the plants, and (3) the temporal increase in concentration of cardiac glycosides in the leaves. The study also provided confirmatory data of previous studies that wild monarch females tend to oviposit onA. humistrata plants containing intermediate concentrations of cardiac glycosides. Cardiac glycoside concentration in the leaves was not correlated with that in the latex. The concentration of cardenolide in the latex is extremely high, constituting an average of 1.2 and 9.5% of the mass of the wet and dry latex, respectively. The data suggest that an increase in water content of the latex is compensated for by an influx of cardenolide with the result that the cardenolide concentration remains constant in the latex systems of plants that are growing naturally. We also observed first instar larvae taking their first bite of milkweed leaves in the field. In addition to confirming other workers findings that monarch larvae possess elaborate “sabotaging” behaviour of the milkweed's latex system, we discovered that several larvae on their first bite involuntarily imbided a small globule of latex and instantly became cataleptic. This catalepsis, lasting up to 10 min, may have been in response to the high concentration of cardenolide present in the latex ofA. humistrata, more than 10 times that in the leaves. The results of the present study suggest that more attention should be directed to plant chemical defenses upon initial attack by first instar insect larvae, rather than attempting correlations of plant chemistry with older larvae that have already passed the early instar gauntlet. The first bite of neonate insects may be the most critical moment for coping with the chemical defenses of many plants and may play a much more important role in the evolution of insect herbivory than has previously been recognized.
Article
Several naturally occurring furanocoumarins such as xanthotoxin cause cell damage by complexing with DNA in the presence of long-wave UV light. Heracleum lanatum, an Umbellifer, contains high concentrations of such compounds in the leaves but survives in sunlight and is a food source for insects, fungi, and man. Microscopic investigations and feeding experiments carried out in long-wave UV show that although the compounds are normally isolated in the petiolar oil ducts, the plant can tolerate xanthotoxin uptake in the transpiration stream. Aphids living on Heracleum take up and bind xanthotoxin fed via a cut stem but are unaffected over short term. Such tolerance in plant and aphid may be due to limited cell divisions during the test, but the biochemical basis of tolerance in growing Heracleum is not known. Various fungi, including pathogens of Umbellifers, show differing sensitivities to xanthotoxin plus UV, perhaps because of differing uptake rates and growth habits.
Article
Recent cladistic analyses are revealing the phylogeny of flowering plants in increasing detail, and there is support for the monophyly of many major groups above the family level. With many elements of the major branching sequence of phylogeny established, a revised suprafamilial classification of flowering plants becomes both feasible and desirable. Here we present a classification of 462 flowering plant families in 40 putatively monophyletic orders and a small number of monophyletic, informal higher groups. The latter are the monocots, commelinoids, eudicots, core eudicots, rosids including eurosids I and II, and asterids including euasterids I and II. Under these informal groups there are also listed a number of families without assignment to order. At the end of the system is an additional list of families of uncertain position for which no firm data exist regarding placement anywhere within the system.