Dissection génétique de la résistance à Colletotrichum lindemuthinum, agent de l'anthracnose, chez deux génotypes représentatifs des pools géniques de Phaseolus vulgaris L.

*INRA, UNité de Génétique et Amélioration des Plantes, 78026 Versailles Cedex Diffusion du document : INRA, UNité de Génétique et Amélioration des Plantes, 78026 Versailles Cedex Diplôme : Dr. Ing

Les leçons du clonage des gènes de résistance spécifiques aux maladies chez les plantes.

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Chez les plantes aussi, des gènes font de la résistance

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Bean pod mottle virus: a new powerful tool for functional genomics studies in [i]Pisum sativum[/i].

International audiencePea (Pisum sativum L.) is an important legume worldwide. The importance of pea in arable rotations and nutritional value for both human and animal consumption have fostered sustained production and different studies to improve agronomic traits of interest. Moreover, complete sequencing of the pea genome is currently underway and will lead to the identification of a large number of genes potentially associated with important agronomic traits. Because stable genetic transformation is laborious for pea, virus-induced gene silencing (VIGS) appears as a powerful alternative technology for determining the function of unknown genes. In this work, we present a rapid and efficient viral inoculation method using DNA infectious plasmids of Bean pod mottle virus (BPMV)-derived VIGS vector. Six pea genotypes with important genes controlling biotic and/or abiotic stresses were found susceptible to BPMV carrying a GFP reporter gene and showed fluorescence in both shoots and roots. In a second step, we investigated 37 additional pea genotypes and found that 30 were susceptible to BPMV and only 7 were resistant. The capacity of BPMV to induce silencing of endogenes was investigated in the most susceptible genotype using two visual reporter genes: PsPDS and PsKORRIGAN1 (PsKOR1) encoding PHYTOENE DESATURASE and a 1,4-β-D-glucanase, respectively. The features of the 'one-step' BPMV-derived VIGS vector include (i) the ease of rub-inoculation, without any need for biolistic or agro-inoculation procedures, (ii) simple cost-effective procedure and (iii) noninterference of viral symptoms with silencing. These features make BPMV the most adapted VIGS vector in pea to make low- to high-throughput VIGS studies

What Is Present at Common Bean Subtelomeres? Large Resistance Gene Clusters, Knobs and Khipu Satellite DNA

In plants, the largest class of resistance (R) gene encodes nucleotide-binding leucine-rich repeat (NB-LRR) proteins. This multigene family is often organized in clusters of tightly linked genes. In the common bean (Phaseolus vulgaris L.) genome, most of the well-characterized large R gene clusters are not randomly distributed since they are often located at the ends of the linkage groups (LG), suggesting that this location is favorable for R gene proliferation. In addition, terminal knobs (heterochromatic blocks) are present at most chromosome (Chr) ends of P. vulgaris, and we have identified a satellite DNA referred to as khipu that is a component of most of them. Plasticity of subtelomeres has been described in various organisms such as yeast and human but is not well documented in plants. In common bean, the B4 cluster of R gene was shown to derive from the Co-2 R gene cluster through an ectopic recombination between non-homologous chromosomes in subtelomeric regions. These unusual features of common bean genome (subtelomeric localization of large NB-LRR sequences, the presence of terminal knobs, and plasticity of subtelomeres) have been investigated with the availability of the complete common bean genome sequence

The "one-step" Bean pod mottle virus (BPMV)derived vector is a functional genomics tool for efficient overexpression of heterologous protein, virus-induced gene silencing and genetic mapping of BPMV R-gene in common bean (Phaseolus vulgaris L.)

Background: Over the last two years, considerable advances have been made in common bean (Phaseolus vulgaris L.) genomics, especially with the completion of the genome sequence and the availability of RNAseq data. However, as common bean is recalcitrant to stable genetic transformation, much work remains to be done for the development of functional genomics tools adapted to large-scale studies. Results: Here we report the successful implementation of an efficient viral vector system for foreign gene expression, virus-induced gene silencing (VIGS) and genetic mapping of a BPMV resistance gene in common bean, using a "one-step" BPMV vector originally developed in soybean. With the goal of developing this vector for high-throughput VIGS studies in common bean, we optimized the conditions for rub-inoculation of infectious BPMV-derived plasmids in common bean cv. Black Valentine. We then tested the susceptibility to BPMV of six cultivars, and found that only Black Valentine and JaloEEP558 were susceptible to BPMV. We used a BPMV-GFP construct to detect the spatial and temporal infection patterns of BPMV in vegetative and reproductive tissues. VIGS of the PHYTOENE DESATURASE (PvPDS) marker gene was successfully achieved with recombinant BPMV vectors carrying fragments ranging from 132 to 391 bp. Finally, we mapped a gene for resistance to BPMV (R-BPMV) at one end of linkage group 2, in the vicinity of a locus (I locus) previously shown to be involved in virus resistance. Conclusions: The " one-step" BPMV vector system therefore enables rapid and simple functional studies in common bean, and could be suitable for large-scale analyses. In the post-genomic era, these advances are timely for the common bean research communit

Development of molecular markers linked to disease resistance genes in common bean based on whole genome sequence

International audienceCommon bean (Phaseolus vulgaris) is the most important grain legume for direct human consumption in the world, particularly in developing countries where it constitutes the main source of protein. Unfortunately, common bean yield stability is constrained by a number of pests and diseases. As use of resistant genotypes is the most economic and ecologically safe means for controlling plant diseases, efforts have been made to genetically characterize resistance genes (R genes) in common bean. Despite its agronomic importance, genomic resources available in common bean were limited until the recent sequencing of common bean genome (Andean genotype G19833). Besides allowing the annotation of Nucleotide Binding-Leucine Rich Repeat (NB-LRR) encoding gene family, which is the prevalent class of disease R genes in plants, access to the whole genome sequence of common bean can be of great help for intense selection to increase the overall efficiency of crop improvement programs using marker-assisted selection (MAS). This review presents the state of the art of common bean NB-LRR gene clusters, their peculiar location in subtelomeres and correlation with genetically characterized monogenic R genes, as well as how the availability of the whole genome sequence can boost the development of molecular markers for MAS

A family of LRR sequences in the vicinity of the Co-2 locus for anthracnose resistance in Phaseolus vulgaris and its potential use in marker-assisted selection

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Inheritance of partial resistance against Colletotrichum lindemuthianum in Phaseolus vulgaris and co-localization of quantitative trait loci with genes involved in specific resistance

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