The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Martin Heil - One of the best experts on this subject based on the ideXlab platform.
-
cyanogenesis of wild Lima bean phaseolus lunatus l is an efficient direct defence in nature
PLOS ONE, 2009Co-Authors: Daniel J Ballhorn, Stefanie Kautz, Martin Heil, Adrian D HegemanAbstract:In natural systems plants face a plethora of antagonists and thus have evolved multiple defence strategies. Lima bean (Phaseolus lunatus L.) is a model plant for studies of inducible indirect anti-herbivore defences including the production of volatile organic compounds (VOCs) and extrafloral nectar (EFN). In contrast, studies on direct chemical defence mechanisms as crucial components of Lima Beans' defence syndrome under natural conditions are nonexistent. In this study, we focus on the cyanogenic potential (HCNp; concentration of cyanogenic glycosides) as a crucial parameter determining Lima Beans' cyanogenesis, i.e. the release of toxic hydrogen cyanide from preformed precursors. Quantitative variability of cyanogenesis in a natural population of wild Lima bean in Mexico was significantly correlated with missing leaf area. Since existing correlations do not by necessity mean causal associations, the function of cyanogenesis as efficient plant defence was subsequently analysed in feeding trials. We used natural chrysomelid herbivores and clonal Lima Beans with known cyanogenic features produced from field-grown mother plants. We show that in addition to extensively investigated indirect defences, cyanogenesis has to be considered as an important direct defensive trait affecting Lima Beans' overall defence in nature. Our results indicate the general importance of analysing ‘multiple defence syndromes’ rather than single defence mechanisms in future functional analyses of plant defences.
-
Quantitative Variability of Direct Chemical Defense in Primary and Secondary Leaves of Lima Bean (Phaseolus lunatus) and Consequences for a Natural Herbivore
Journal of Chemical Ecology, 2008Co-Authors: Daniel J Ballhorn, Susann Schiwy, Manfred Jensen, Martin HeilAbstract:Ontogenetic variability in chemical plant defenses against herbivores is a common phenomenon, but the effects of this variability on herbivore–plant interactions are little understood. In a previous study on Lima bean ( Phaseolus lunatus ), we found a trade-off between cyanogenesis, a direct defense, and the release of herbivore-induced volatile organic compounds (VOCs; mainly functioning as an indirect defense). Moreover, the expression of these two defenses could change during plant ontogeny. The present study aimed at elucidating whether such ontogenetic changes in plant defense can affect herbivore–plant interactions. We quantified feeding rates of a natural insect herbivore, the Mexican bean beetle ( Epilachna varivestis ), on primary and secondary leaves of individual Lima bean plants. These insects strongly preferred low cyanogenic primary leaves over high cyanogenic secondary leaves. Although weakly defended by cyanogenesis, Lima Beans’ primary leaves showed protein concentrations and photosynthetic activities that did not differ significantly from secondary leaves at the time of analysis. Based on our findings, we suggest that Lima Beans’ long-lived primary leaves function as efficient source organs, even beyond the stage of seedlings. This hypothesis may explain why primary leaves express a strong indirect defense by the release of herbivore induced VOCs.
-
increased availability of extrafloral nectar reduces herbivory in Lima bean plants phaseolus lunatus fabaceae
Basic and Applied Ecology, 2005Co-Authors: Christian Kost, Martin HeilAbstract:Summary Lima bean (Phaseolus lunatus) features two inducible indirect defences to protect itself against herbivores. Besides the emission of plant volatiles, extrafloral nectar is secreted to attract carnivorous arthropods to herbivore-damaged plants. The activation of both putative defences efficiently protects Lima Beans from leaf damage. In a field experiment in Mexico, we studied whether extrafloral nectar alone can benefit the Lima bean under natural conditions. An artificial blend mimicking natural nectar both qualitatively and quantitatively was repeatedly applied to Lima bean tendrils. Ants, wasps and flies were significantly more abundant on treated tendrils than on untreated controls already after 1 week (i.e. after two treatment applications). Sticky traps were used to assess the functional groups of flying insects attracted to the Lima Beans. After 24 h, 71% of all trapped flies and 98% of all wasps belonged to families comprising either parasitoid or predatory species. This observation suggests that also some of the flying visitors have played a role as putative defenders of Lima Beans. Most of the trapped flies belonged to the families Dolichopodidae and Phoridae (each ca. one third of all individuals). Two thirds of the wasps belonged to Chalcidoidea (68%). All ant species that had been collected manually belonged to generalist genera with Camponotus novogranadensis and Cephalotes minutus being most regularly encountered on study tendrils. An additional experiment, where both ‘nectar’ and ‘control’ tendrils were treated with artificial nectar, revealed that ants responded with an increased abundance on tendrils that had experienced the ‘nectar’ treatment before. After 25 days, the treated tendrils showed a significantly reduced herbivory as compared to controls. The mere presence of increased amounts of extrafloral nectar thus can benefit the Lima bean under natural conditions.
-
induction of two indirect defences benefits Lima bean phaseolus lunatus fabaceae in nature
Journal of Ecology, 2004Co-Authors: Martin HeilAbstract:Summary 1 Herbivore damage often induces the release of herbivore-induced plant volatiles (HIPVs) or the secretion of extrafloral nectar (EFN). The purpose of this study was to induce such proposed indirect defence responses in plants growing in their natural environment and to monitor the effects on vegetative and generative traits such as herbivory, plant growth and fruit set. 2 I tested whether mature wild Lima Beans (Phaseolus lunatus, Fabaceae) growing in Mexico could be reliably induced to produce HIPVs and EFN in response to application of the phytohormone, jasmonic acid (JA), and investigated whether this treatment leads to any benefit to the plants. 3 Eleven HIPVs were released from JA-treated leaves at significantly higher amounts than from control leaves, and only one (methylsalicylate) at significantly lower amounts than from controls. Treatment with JA increased EFN secretion on leaves on average by more than 30 times and on bracts by more than 20 times. EFN production, which has not previously been described in Lima bean, represents a second induced indirect resistance trait of this species. 4 JA treatment reduced both the number of dead shoot tips and leaf damage by herbivores. Treated tendrils grew faster and produced more leaves than controls. At the end of the experiment, treated tendrils bore c. two times more inflorescences and three times more fruits than controls. 5 Repeated treatment with JA resulted in a combined induction of HIPVs and EFN and strongly benefited wild Lima Beans. The plants suffered less from the consequences of herbivore attack, supporting the use of the term ‘induced defences’ for these traits. JA-induced defences thus can significantly benefit Lima bean under natural conditions.
Daniel J Ballhorn - One of the best experts on this subject based on the ideXlab platform.
-
chapter 14 cyanogenic glycosides in nuts and seeds
Nuts and Seeds in Health and Disease Prevention, 2011Co-Authors: Daniel J BallhornAbstract:Publisher Summary Many plant species actively synthesize and accumulate cyanide-containing compounds. These cyanogenic plants have the ability to release hydrogen cyanide (HCN) up to toxic thresholds in response to cell disintegration. This chapter examines cyanogenic nuts and seeds. The concentrations of cyanide-containing compounds in nuts and seeds vary widely; however, in some species, such as Prunus amygdalus (almonds), P. armeniaca (apricots), and Phaseolus lunatus (Lima bean), they can reach toxic thresholds. Most cyanogenic glycosides are derived from the five hydrophobic protein amino acids, tyrosine, phenylalanine, valine, leucine, and isoleucine. In the course of the biosynthetic pathway the specific amino acids are hydroxylated to N-hydroxylamino acids, aldoximes, and then to nitriles serving as intermediates. Because HCN generally is toxic to all eukaryotes, including the plant itself, the accumulation of this toxin as an inactive precursor is essential to prevent autotoxicity. Although potentially toxic, cyanogenic nuts and seeds are often characterized by exceptionally high nutritive values. All of the economically most important cyanogenic nuts and seeds (i.e., almonds, macadamia nuts, Lima Beans, and flaxseed) contain health-promoting compositions of fatty acids, minerals, vitamins, and carbohydrates. Taking into consideration the possible health risk arising from consumption of inappropriately processed plant materials or the selection of highly cyanogenic crop plant genotypes, cyanogenic nuts and seeds represent excellent food sources.
-
cyanogenesis of wild Lima bean phaseolus lunatus l is an efficient direct defence in nature
PLOS ONE, 2009Co-Authors: Daniel J Ballhorn, Stefanie Kautz, Martin Heil, Adrian D HegemanAbstract:In natural systems plants face a plethora of antagonists and thus have evolved multiple defence strategies. Lima bean (Phaseolus lunatus L.) is a model plant for studies of inducible indirect anti-herbivore defences including the production of volatile organic compounds (VOCs) and extrafloral nectar (EFN). In contrast, studies on direct chemical defence mechanisms as crucial components of Lima Beans' defence syndrome under natural conditions are nonexistent. In this study, we focus on the cyanogenic potential (HCNp; concentration of cyanogenic glycosides) as a crucial parameter determining Lima Beans' cyanogenesis, i.e. the release of toxic hydrogen cyanide from preformed precursors. Quantitative variability of cyanogenesis in a natural population of wild Lima bean in Mexico was significantly correlated with missing leaf area. Since existing correlations do not by necessity mean causal associations, the function of cyanogenesis as efficient plant defence was subsequently analysed in feeding trials. We used natural chrysomelid herbivores and clonal Lima Beans with known cyanogenic features produced from field-grown mother plants. We show that in addition to extensively investigated indirect defences, cyanogenesis has to be considered as an important direct defensive trait affecting Lima Beans' overall defence in nature. Our results indicate the general importance of analysing ‘multiple defence syndromes’ rather than single defence mechanisms in future functional analyses of plant defences.
-
Quantitative Variability of Direct Chemical Defense in Primary and Secondary Leaves of Lima Bean (Phaseolus lunatus) and Consequences for a Natural Herbivore
Journal of Chemical Ecology, 2008Co-Authors: Daniel J Ballhorn, Susann Schiwy, Manfred Jensen, Martin HeilAbstract:Ontogenetic variability in chemical plant defenses against herbivores is a common phenomenon, but the effects of this variability on herbivore–plant interactions are little understood. In a previous study on Lima bean ( Phaseolus lunatus ), we found a trade-off between cyanogenesis, a direct defense, and the release of herbivore-induced volatile organic compounds (VOCs; mainly functioning as an indirect defense). Moreover, the expression of these two defenses could change during plant ontogeny. The present study aimed at elucidating whether such ontogenetic changes in plant defense can affect herbivore–plant interactions. We quantified feeding rates of a natural insect herbivore, the Mexican bean beetle ( Epilachna varivestis ), on primary and secondary leaves of individual Lima bean plants. These insects strongly preferred low cyanogenic primary leaves over high cyanogenic secondary leaves. Although weakly defended by cyanogenesis, Lima Beans’ primary leaves showed protein concentrations and photosynthetic activities that did not differ significantly from secondary leaves at the time of analysis. Based on our findings, we suggest that Lima Beans’ long-lived primary leaves function as efficient source organs, even beyond the stage of seedlings. This hypothesis may explain why primary leaves express a strong indirect defense by the release of herbivore induced VOCs.
-
plant cyanogenesis of phaseolus lunatus and its relevance for herbivore plant interaction the importance of quantitative data
Journal of Chemical Ecology, 2005Co-Authors: Daniel J Ballhorn, Reinhard Lieberei, Joerg U GanzhornAbstract:Quantitative experimental results on the antiherbivorous effect of cyanogenesis are rare. In our analyses, we distinguished between the total amount of cyanide-containing compounds stored in a given tissue [cyanogenic potential (HCNp)] and the capacity for release of HCN per unit time (HCNc) from these cyanogenic precursors as a reaction to herbivory. We analyzed the impact of these cyanogenic features on herbivorous insects using different accessions of Lima Beans (Phaseolus lunatus L.) with different cyanogenic characteristics in their leaves and fourth instars of the generalist herbivore Schistocerca gregaria Forskal (Orthoptera, Acrididae). Young leaves exhibit a higher HCNp and HCNc than mature leaves. This ontogenetic variability of cyanogenesis was valid for all accessions studied. In no-choice bioassays, feeding of S. gregaria was reduced on high cyanogenic Lima Beans compared with low cyanogenic Beans. A HCNp of about 15 μmol cyanide/g leaf (fresh weight) with a corresponding HCNc of about 1 μmol HCN released from leaf material within the first 10 min after complete tissue disintegration appears to be a threshold at which the first repellent effects on S. gregaria were observed. The repellent effect of cyanogenesis increased above these thresholds of HCNp and HCNc. No repellent action of cyanogenesis was observed on plants with lower HCNp and HCNc. These low cyanogenic accessions of P. lunatus were consumed extensively—with dramatic consequences for the herbivore. After consumption, locusts showed severe symptoms of intoxication. Choice assays confirmed the feeding preference of locusts for low over high cyanogenic leaf material of P. lunatus. The bioassays revealed total losses of HCN between 90 and 99% related to the estimated amount of ingested cyanide-containing compounds by the locusts. This general finding was independent of the cyanogenic status (high or low) of the leaf material.
Betty Benrey - One of the best experts on this subject based on the ideXlab platform.
-
the large seed size of domesticated Lima Beans mitigates intraspecific competition among seed beetle larvae
Frontiers in Ecology and Evolution, 2017Co-Authors: Maximilien A C Cuny, Gwen J Shlichta, Betty BenreyAbstract:The domestication of Beans has selected for larger seeds in cultivated plants compared to their wild relatives. This has not only resulted in an enhanced resource for humans, but also for the insects that feed on these seeds. Seed beetles that attack wild and cultivated seeds often lay several eggs on a single seed. We hypothesized that the larger seed size of domesticated Beans will mitigate the competition among the larvae that hatch from these eggs, with important implications for their growth and survival. To test this we examined how seed size of wild and cultivated Phaseolus lunatus (Lima bean) affect the performance of the Mexican bean weevil Zabrotes subfasciatus, an important pest of Beans in Mexico. A negative correlation was found between the initial number of eggs on a seed and the weight of female beetles that emerged, but only for the much smaller wild seeds. Similarly, beetle survival was found to be negatively correlated with competition intensity only on wild seeds. Our results imply that by selecting for larger seeds, domestication of Phaseolus lunatus has reduced the intensity of intraspecific larval competition of Z. subfasciatus.
-
Variation in Cyanogenic Glycosides Across Populations of Wild Lima Beans (Phaseolus lunatus) Has No Apparent Effect on Bruchid Beetle Performance
Journal of Chemical Ecology, 2014Co-Authors: J. Gwen Shlichta, Gaetan Glauser, Betty BenreyAbstract:Cyanogenic glycosides (CNGs) act as feeding or oviposition deterrents and are toxic after enzymatic hydrolysis, thus negatively affecting herbivore performance. While most studies on CNGs focus on leaf herbivores, here we examined seeds from natural populations of Phaseolus lunatus in Mexico. The predominant CNGs, linamarin and lotaustralin, were quantified for each population by using ultra-high pressure liquid chromatography-mass spectrometry. We also examined whether there was a correlation between the concentration of CNGs and the performance of the Mexican bean beetle, Zabrotes subfasciatus , on seeds from each population^. The concentrations of CNGs in the seeds were relatively high compared to the leaves and were significantly variable among populations. Surprisingly, this had little effect on the performance of the bruchid beetles. Zabrotes subfasciatus can tolerate high concentrations of CNGs, most likely because of the limited β-glucosidase activity in the seeds. Seed herbivory does not appear to liberate hydrogen cyanide due to the low water content in the seed. This study illustrates the importance of quantifying the natural variation and activity of toxic compounds in order to make relevant biological inferences about their role in defense against herbivores.
Maria Isabel Chacon Sanchez - One of the best experts on this subject based on the ideXlab platform.
-
gene pools in wild Lima bean phaseolus lunatus l from the americas evidences for an andean origin and past migrations
Molecular Phylogenetics and Evolution, 2010Co-Authors: Martha L Serranoserrano, Daniel G Debouck, Jorge Hernandeztorres, Genis Castillovillamizar, Maria Isabel Chacon SanchezAbstract:The aims of this research were to assess the genetic structure of wild Phaseolus lunatus L. in the Americas and the hypothesis of a relatively recent Andean origin of the species. For this purpose, nuclear and non-coding chloroplast DNA markers were analyzed in a collection of 59 wild Lima bean accessions and six allied species. Twenty-three chloroplast and 28 nuclear DNA haplotypes were identified and shown to be geographically structured. Three highly divergent wild Lima bean gene pools, AI, MI, and MII, with mostly non-overlapping geographic ranges, are proposed. The results support an Andean origin of wild Lima Beans during Pleistocene times and an early divergence of the three gene pools at an age that is posterior to completion of the Isthmus of Panama and major Andean orogeny. Gene pools would have evolved and reached their current geographic distribution mainly in isolation and therefore are of high priority for conservation and breeding programs.
Adrian D Hegeman - One of the best experts on this subject based on the ideXlab platform.
-
cyanogenesis of wild Lima bean phaseolus lunatus l is an efficient direct defence in nature
PLOS ONE, 2009Co-Authors: Daniel J Ballhorn, Stefanie Kautz, Martin Heil, Adrian D HegemanAbstract:In natural systems plants face a plethora of antagonists and thus have evolved multiple defence strategies. Lima bean (Phaseolus lunatus L.) is a model plant for studies of inducible indirect anti-herbivore defences including the production of volatile organic compounds (VOCs) and extrafloral nectar (EFN). In contrast, studies on direct chemical defence mechanisms as crucial components of Lima Beans' defence syndrome under natural conditions are nonexistent. In this study, we focus on the cyanogenic potential (HCNp; concentration of cyanogenic glycosides) as a crucial parameter determining Lima Beans' cyanogenesis, i.e. the release of toxic hydrogen cyanide from preformed precursors. Quantitative variability of cyanogenesis in a natural population of wild Lima bean in Mexico was significantly correlated with missing leaf area. Since existing correlations do not by necessity mean causal associations, the function of cyanogenesis as efficient plant defence was subsequently analysed in feeding trials. We used natural chrysomelid herbivores and clonal Lima Beans with known cyanogenic features produced from field-grown mother plants. We show that in addition to extensively investigated indirect defences, cyanogenesis has to be considered as an important direct defensive trait affecting Lima Beans' overall defence in nature. Our results indicate the general importance of analysing ‘multiple defence syndromes’ rather than single defence mechanisms in future functional analyses of plant defences.