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Gruet C, Muller D, Moënne-Loccoz Y. Significance of the Diversification of Wheat Species for the Assembly and Functioning of the Root-Associated Microbiome. Front Microbiol 2022; 12:782135. [PMID: 35058901 PMCID: PMC8764353 DOI: 10.3389/fmicb.2021.782135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 11/30/2021] [Indexed: 12/15/2022] Open
Abstract
Wheat, one of the major crops in the world, has had a complex history that includes genomic hybridizations between Triticum and Aegilops species and several domestication events, which resulted in various wild and domesticated species (especially Triticum aestivum and Triticum durum), many of them still existing today. The large body of information available on wheat-microbe interactions, however, was mostly obtained without considering the importance of wheat evolutionary history and its consequences for wheat microbial ecology. This review addresses our current understanding of the microbiome of wheat root and rhizosphere in light of the information available on pre- and post-domestication wheat history, including differences between wild and domesticated wheats, ancient and modern types of cultivars as well as individual cultivars within a given wheat species. This analysis highlighted two major trends. First, most data deal with the taxonomic diversity rather than the microbial functioning of root-associated wheat microbiota, with so far a bias toward bacteria and mycorrhizal fungi that will progressively attenuate thanks to the inclusion of markers encompassing other micro-eukaryotes and archaea. Second, the comparison of wheat genotypes has mostly focused on the comparison of T. aestivum cultivars, sometimes with little consideration for their particular genetic and physiological traits. It is expected that the development of current sequencing technologies will enable to revisit the diversity of the wheat microbiome. This will provide a renewed opportunity to better understand the significance of wheat evolutionary history, and also to obtain the baseline information needed to develop microbiome-based breeding strategies for sustainable wheat farming.
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Affiliation(s)
| | | | - Yvan Moënne-Loccoz
- Univ Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), VetAgro Sup, UMR 5557 Ecologie Microbienne, Villeurbanne, France
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Espinosa-García FJ, García-Rodríguez YM, Bravo-Monzón AE, Vega-Peña EV, Delgado-Lamas G. Implications of the foliar phytochemical diversity of the avocado crop Persea americana cv. Hass in its susceptibility to pests and pathogens. PeerJ 2021; 9:e11796. [PMID: 35070514 PMCID: PMC8759378 DOI: 10.7717/peerj.11796] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 06/25/2021] [Indexed: 11/20/2022] Open
Abstract
Phytochemical diversity (PD) can be considered as a defensive trait; it can operate through single plant secondary metabolites or usually as complex mixtures of them. We tested the more diversity-better defense hypothesis correlating the leaf plant secondary metabolites (PSMs) with the incidence of plant enemies on Hass avocado trees. We expected a negative correlation between the occurrence of plant enemies and PD metrics. Also, as intraspecific PSMs polymorphisms in plant populations are common, we studied the incidence of plant enemies on Hass avocado trees representing chemical variants (chemotypes). We expected a differential incidence of plant enemies among trees grouped by their mono and sesquiterpene + phenylpropanoid chemotypes. We analyzed foliar hexane extracts from 236 trees in 17 orchards by gas chromatography and for the incidence of red mite, thrips, whitefly, avocado branch borer, fruit rot, scab, and peduncle collar blight. The predicted negative correlation between the plant enemies’ incidence and the phytochemical metrics did not occur. To determine the relationship between enemy incidence and chemotypes we grouped the trees by cluster analysis using a matrix of PSMs in each tree. Most trees were grouped under four out of 23 chemotypes. Branch borers attacked trees of low-frequency chemotypes more frequently than trees with common chemotypes. The incidence of five plant enemies was different among the predominant chemotypes. The hypothesis of more diversity-better defense was not supported by the correlations between the phytochemical diversity and the incidence of pests and pathogens in Hass avocado orchards. Based on our results, we hypothesize that phytochemical diversity function as a defensive trait relies more on differentiation among individuals in a population than on the sole increase of chemical diversity. Also, the differential incidence of pests and pathogens on trees classified by their foliar chemotypes implies that these susceptibility or resistance markers represent potential useful tools for Hass avocado orchard pest management.
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Affiliation(s)
- Francisco J. Espinosa-García
- Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Morelia, Michoacán, México
| | - Yolanda M. García-Rodríguez
- Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Morelia, Michoacán, México
| | - Angel E. Bravo-Monzón
- Escuela Nacional de Estudios Superiores Mérida, Universidad Nacional Autónoma de México, Mérida, Yucatán, México
| | - Ernesto V. Vega-Peña
- Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Morelia, Michoacán, México
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3
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Bioprospecting of Sechium spp. varieties for the selection of characters with pharmacological activity. Sci Rep 2021; 11:6185. [PMID: 33731771 PMCID: PMC7969600 DOI: 10.1038/s41598-021-85676-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 03/04/2021] [Indexed: 11/08/2022] Open
Abstract
Bioprospecting identifies new sources of compounds with actual or potential economic value that come from biodiversity. An analysis was performed regarding bioprospecting purposes in ten genotypes of Sechium spp., through a meta-analysis of 20 information sources considering different variables: five morphological, 19 biochemical, anti-proliferative activity of extracts on five malignant cell lines, and 188 polymorphic bands of amplified fragment length polymorphisms, were used in order to identify the most relevant variables for the design of genetic interbreeding. Significant relationships between morphological and biochemical characters and anti-proliferative activity in cell lines were obtained, with five principal components for principal component analysis (SAS/ETS); variables were identified with a statistical significance (< 0.7 and Pearson values ≥ 0.7), with 80.81% of the accumulation of genetic variation and 110 genetic bands. Thirty-nine (39) variables were recovered using NTSYSpc software where 30 showed a Pearson correlation (> 0.5) and nine variables (< 0.05), Finally, using a cladistics analysis approach highlighted 65 genetic bands, in addition to color of the fruit, presence of thorns, bitter flavor, piriform and oblong shape, and also content of chlorophylls a and b, presence of cucurbitacins, and the IC50 effect of chayote extracts on the four cell lines.
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Bakhtiari M, Rasmann S. Variation in Below-to Aboveground Systemic Induction of Glucosinolates Mediates Plant Fitness Consequences under Herbivore Attack. J Chem Ecol 2020; 46:317-329. [PMID: 32060668 DOI: 10.1101/810432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 01/20/2020] [Accepted: 01/28/2020] [Indexed: 05/22/2023]
Abstract
Plants defend themselves against herbivore attack by constitutively producing toxic secondary metabolites, as well as by inducing them in response to herbivore feeding. Induction of secondary metabolites can cross plant tissue boundaries, such as from root to shoot. However, whether the potential for plants to systemically induce secondary metabolites from roots to shoots shows genetic variability, and thus, potentially, is under selection conferring fitness benefits to the plants is an open question. To address this question, we induced 26 maternal plant families of the wild species Cardamine hirsuta belowground (BG) using the wound-mimicking phytohormone jasmonic acid (JA). We measured resistance against a generalist (Spodoptera littoralis) and a specialist (Pieris brassicae) herbivore species, as well as the production of glucosinolates (GSLs) in plants. We showed that BG induction increased AG resistance against the generalist but not against the specialist, and found substantial plant family-level variation for resistance and GSL induction. We further found that the systemic induction of several GSLs tempered the negative effects of herbivory on total seed set production. Using a widespread natural system, we thus confirm that BG to AG induction has a strong genetic component, and can be under positive selection by increasing plant fitness. We suggest that natural variation in systemic induction is in part dictated by allocation trade-offs between constitutive and inducible GSL production, as well as natural variation in AG and BG herbivore attack in nature.
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Affiliation(s)
- Moe Bakhtiari
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland.
| | - Sergio Rasmann
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
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Variation in Below-to Aboveground Systemic Induction of Glucosinolates Mediates Plant Fitness Consequences under Herbivore Attack. J Chem Ecol 2020; 46:317-329. [DOI: 10.1007/s10886-020-01159-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 01/20/2020] [Accepted: 01/28/2020] [Indexed: 10/25/2022]
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6
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Pérez-Alquicira J, van der Knaap E, Mercer K, McHale L, Mitchell T, Luna-Ruiz J, Texocotitla-Vázquez E, Vargas-Ponce O, Michel A. Genetic Structure of Liriomyza trifolii (Diptera: Agromyzidae) Associated With Host Plants From Southeastern Mexico. ENVIRONMENTAL ENTOMOLOGY 2019; 48:253-262. [PMID: 30596990 DOI: 10.1093/ee/nvy184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Indexed: 06/09/2023]
Abstract
Host-associated differentiation (HAD) has played a major role in insect diversification at both macroevolutionary and microevolutionary scales. This evolutionary process has been reported in insects associated with wild and domesticated plant species. In particular, domesticated species harbor large genetic and phenotypic diversity associated with traits of human interest, including variation in nutrition, phenology, fruit, and leaf shape. This diversity may alter selection regimes affecting insect evolution and host specialization. The genus Liriomyza includes highly polyphagous species that are characterized for living and feeding inside plant leaves. Ecological and genetic data suggest the presence of cryptic species within this genus. Moreover, there is evidence of HAD in a group of populations of Liriomyza trifolii (Burgess) associated with Capsicum annum L. (Solanaceae). In this work, we explored HAD in L. trifolii populations from southeastern Mexico, and inquire into differentiation specific to peppers based on cytochrome oxidase I. We also evaluated the relationship between the genetic structure of leafminers and the different types of C. annuum. Our main results did not support previous findings of specialization of L. trifolli on C. annuum. Nevertheless, we found a divergent group of haplotypes associated to Allium cepa (Aspargales: Amaryllidaceae) in sympatric condition to Physalis philadelphica Lam. (Solanales: Solanaceae) and C. annum, suggesting the presence of HAD, as well as significant genetic differentiation of L. trifolii associated to peppers from Oaxaca and Yucatán.
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Affiliation(s)
- Jessica Pérez-Alquicira
- Departamento de Botánica y Zoología, CONACYT - Laboratorio Nacional de Identificación y Caracterización Vegetal, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Zapopan, Mexico
| | - Esther van der Knaap
- Department of Horticulture, University of Georgia, Athens, GA
- Department of Horticulture and Crop Sciences, Ohio State University, Wooster, OH
| | - Kristin Mercer
- Department of Horticulture and Crop Science, Ohio State University, Columbus, OH
| | - Leah McHale
- Department of Horticulture and Crop Science, Ohio State University, Columbus, OH
| | - Thomas Mitchell
- Department of Plant Pathology, Ohio State University, Columbus, OH
| | - Jose Luna-Ruiz
- Centro de Ciencias Agropecuarias, Universidad Autónoma de Aguascalientes, Aguascalientes, México
| | | | - Ofelia Vargas-Ponce
- Departamento de Botánica y Zoología, CUCBA, Universidad de Guadalajara, Zapopan, Jalisco, México
| | - Andy Michel
- Department of Entomology, Ohio State University, Wooster, OH
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Moreira X, Abdala-Roberts L, Gols R, Francisco M. Plant domestication decreases both constitutive and induced chemical defences by direct selection against defensive traits. Sci Rep 2018; 8:12678. [PMID: 30140028 PMCID: PMC6107632 DOI: 10.1038/s41598-018-31041-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 08/10/2018] [Indexed: 11/27/2022] Open
Abstract
Studies reporting domestication effects on plant defences have focused on constitutive, but not on induced defences. However, theory predicts a trade-off between constitutive (CD) and induced defences (ID), which intrinsically links both defensive strategies and argues for their joint consideration in plant domestications studies. We measured constitutive and induced glucosinolates in wild cabbage (Brassica oleracea ssp. oleracea) and two domesticated varieties (B. oleracea var. acephala and B. oleracea var. capitata) in which the leaves have been selected to grow larger. We also estimated leaf area (proxy of leaf size) to assess size-defence trade-offs and whether domestication effects on defences are indirect via selection for larger leaves. Both CD and ID were lower in domesticated than in wild cabbage and they were negatively correlated (i.e. traded off) in all of the cabbage lines studied. Reductions in CD were similar in magnitude for leaves and stems, and CD and leaf size were uncorrelated. We conclude that domestication of cabbage has reduced levels not only constitutive defences but also their inducibility, and that reductions in CD may span organs not targeted by breeding. This reduction in defences in domesticated cabbage is presumably the result of direct selection rather than indirect effects via trade-offs between size and defences.
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Affiliation(s)
- Xoaquín Moreira
- Misión Biológica de Galicia (MBG-CSIC), Apartado de correos 28, 36080, Pontevedra, Galicia, Spain.
| | - Luis Abdala-Roberts
- Departamento de Ecología Tropical, Campus de Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Yucatán, Apartado Postal 4-116, Itzimná, 97000, Mérida, Yucatán, Mexico
| | - Rieta Gols
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA, Wageningen, The Netherlands
| | - Marta Francisco
- Misión Biológica de Galicia (MBG-CSIC), Apartado de correos 28, 36080, Pontevedra, Galicia, Spain.
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8
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Gaillard MDP, Glauser G, Robert CAM, Turlings TCJ. Fine-tuning the 'plant domestication-reduced defense' hypothesis: specialist vs generalist herbivores. THE NEW PHYTOLOGIST 2018; 217:355-366. [PMID: 28877341 DOI: 10.1111/nph.14757] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 07/14/2017] [Indexed: 05/19/2023]
Abstract
Domesticated plants are assumed to have weakened chemical defenses. We argue, however, that artificial selection will have maintained defense traits against specialized herbivores that have coexisted with the crops throughout their domestication. We assessed the performance of eight species of insect herbivores from three feeding guilds on six European maize lines and six populations of their wild ancestor, teosinte. A metabolomics approach was used in an attempt to identify compounds responsible for observed differences in insect performance. Insects consistently performed better on maize than on teosinte. As hypothesized, this difference was greater for generalist herbivores that are normally not found on teosinte. We also found clear differences in defense metabolites among the different genotypes, but none that consistently correlated with differences in performance. Concentrations of benzoxazinoids, the main chemical defense in maize, tended to be higher in leaves of teosinte, but the reverse was true for the roots. It appears that chemical defenses that target specialized insects are still present at higher concentrations in cultivated maize than compounds that are more effective against generalists. These weakened broad-spectrum defenses in crops may explain the successes of novel pests.
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Affiliation(s)
- Mickaël D P Gaillard
- Laboratory for Fundamental and Applied Research in Chemical Ecology (FARCE), University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
| | - Gaétan Glauser
- Neuchâtel Platform of Analytical Chemistry (NPAC), University of Neuchâtel, Avenue de Bellevaux 51, 2000, Neuchâtel, Switzerland
| | - Christelle A M Robert
- Laboratory for Fundamental and Applied Research in Chemical Ecology (FARCE), University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
- Institute of Plant Sciences, Section Biotic Interactions, University of Bern, Altenbergrain 21, 3013, Bern, Switzerland
| | - Ted C J Turlings
- Laboratory for Fundamental and Applied Research in Chemical Ecology (FARCE), University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
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Cuny MAC, Shlichta GJ, Benrey B. The Large Seed Size of Domesticated Lima Beans Mitigates Intraspecific Competition among Seed Beetle Larvae. Front Ecol Evol 2017. [DOI: 10.3389/fevo.2017.00145] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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10
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Rowen E, Kaplan I. Eco-evolutionary factors drive induced plant volatiles: a meta-analysis. THE NEW PHYTOLOGIST 2016; 210:284-94. [PMID: 26725245 DOI: 10.1111/nph.13804] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 11/11/2015] [Indexed: 05/18/2023]
Abstract
Herbivore-induced plant volatiles (HIPVs) mediate critical ecological functions, but no studies have quantitatively synthesized data published on HIPVs to evaluate broad patterns. We tested three hypotheses that use eco-evolutionary theory to predict volatile induction: feeding guild (chewing arthropods > sap feeders), diet breadth (specialist herbivores > generalists), and selection history (domesticated plants < wild species). To test these hypotheses, we extracted data from 236 experiments that report volatiles produced by herbivore-damaged and undamaged plants. These data were subjected to meta-analysis, including effects on total volatiles and major biochemical classes. Overall, we found that chewers induced more volatiles than sap feeders, for both total volatiles and most volatile classes (e.g. green leaf volatiles, monoterpenes). Although specialist herbivores induced more total volatiles than generalists, this was inconsistent across chemical classes. Contrary to our expectation, domesticated species induced stronger volatile responses than wild species, even when controlling for plant taxonomy. Surprisingly, this is the first quantitative synthesis of published studies on HIPVs. Our analysis provides support for perceptions in the published literature (chewers > sap feeders), while challenging other commonly held notions (wild > crop). Despite the large number of experiments, we identified several gaps in the existing literature that should guide future investigations.
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Affiliation(s)
- Elizabeth Rowen
- Department of Entomology, The Pennsylvania State University, University Park, PA, 16802-3508, USA
| | - Ian Kaplan
- Department of Entomology, Purdue University, 901 W. State Street, West Lafayette, IN, 47907, USA
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Chen YH, Gols R, Benrey B. Crop domestication and its impact on naturally selected trophic interactions. ANNUAL REVIEW OF ENTOMOLOGY 2015; 60:35-58. [PMID: 25341108 DOI: 10.1146/annurev-ento-010814-020601] [Citation(s) in RCA: 180] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Crop domestication is the process of artificially selecting plants to increase their suitability to human requirements: taste, yield, storage, and cultivation practices. There is increasing evidence that crop domestication can profoundly alter interactions among plants, herbivores, and their natural enemies. Overall, little is known about how these interactions are affected by domestication in the geographical ranges where these crops originate, where they are sympatric with the ancestral plant and share the associated arthropod community. In general, domestication consistently has reduced chemical resistance against herbivorous insects, improving herbivore and natural enemy performance on crop plants. More studies are needed to understand how changes in morphology and resistance-related traits arising from domestication may interact with environmental variation to affect species interactions across multiple scales in agroecosystems and natural ecosystems.
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Affiliation(s)
- Yolanda H Chen
- Department of Plant and Soil Sciences, University of Vermont, Burlington, Vermont 05405;
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Abstract
The accumulation of isoflavonoid phytoalexins was studied in several Colombian bean cultivars resistant and susceptible to Colletotrichum lindemuthianum fungus, the causal agent of anthrachnose disease. A time-course accumulation analysis on seedlings treated with CuCl2 showed that phaseollin production was higher in resistant cultivars than in susceptible ones. Also, a defensive role of phytoalexins was demostrated when extracts containing this pterocarpan exhibited antifungal activity against C. lindemuthianum. In addition, the elicitor activity of some aminosugars was also established.
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13
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Lindig-Cisneros R, Dirzo R, Espinosa-García FJ. Effects of domestication and agronomic selection on phytoalexin antifungal defense in Phaseolus
beans. Ecol Res 2002. [DOI: 10.1046/j.1440-1703.2002.00491.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Hammerschmidt R, Dann EK. The role of phytoalexins in plant protection. NOVARTIS FOUNDATION SYMPOSIUM 1999; 223:175-87; discussion 188-90. [PMID: 10549555 DOI: 10.1002/9780470515679.ch12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Plants resist pathogens with combinations of constitutive and induced defences. Of the induced defences, phytoalexin production has received much attention since the phytoalexin concept was introduced over 50 years ago. However, the specific role of phytoalexins in disease resistance is not clear for the majority of host-parasite systems. Much of the research on phytoalexins has relied on the identification of induced antifungal compounds and correlating their presence with resistance. Although an important first step, more definitive studies are needed. Approaches that use in situ localization and quantification have provided good evidence that phytoalexins can accumulate at the right time, concentration, and location to be effective in resistance. Studies on phytoalexin tolerance in pathogenic fungi have also shown a relationship between virulence and the ability of fungi to detoxify phytoalexins. Use of mutants deficient in phytoalexin synthesis and elucidating biosynthetic pathways provide other approaches to evaluating the role of phytoalexins. These approaches will be illustrated using the Arabidopsis-camalexin system and other selected examples. Studies on natural variation in phytoalexin production and the accumulation of phytoalexins under field conditions will be presented as another means of evaluating the role of these compounds in resistance to pathogens and other pests.
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Affiliation(s)
- R Hammerschmidt
- Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824-1312, USA
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Hammerschmidt R. PHYTOALEXINS: What Have We Learned After 60 Years? ANNUAL REVIEW OF PHYTOPATHOLOGY 1999; 37:285-306. [PMID: 11701825 DOI: 10.1146/annurev.phyto.37.1.285] [Citation(s) in RCA: 167] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
One of the best and longest-studied defense response of plants to infection is the induced accumulation of antimicrobial, low-molecular-weight secondary metabolites known as phytoalexins. Since the phytoalexin hypothesis was first proposed in 1940, a role for these compounds in defense has been revealed through several experimental approaches. Support has come, for example, through studies on the rate of phytoalexins in relation to cessation of pathogen development, quantification of phytoalexins at the infection site, and relationship of pathogen virulence to the phytoalexin tolerance. Evidence in support of phytoalexins in resistance as well some recent advances in phytoalexin biosynthesis are reviewed. Criteria for evaluating a role for phytoalexins in disease resistance are also discussed.
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Affiliation(s)
- Ray Hammerschmidt
- Department of Botany and Plant Pathology, Michigan State University, East Lansing, Michigan 48824; e-mail:
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