Genetic diversity, linkage disequilibrium and power of a large grapevine (Vitis vinifera L) diversity panel newly designed for association studies

UMR-AGAP Equipe DAVV (Diversité, adaptation et amélioration de la vigne) ; équipe ID (Intégration de Données)International audienceAbstractBackgroundAs for many crops, new high-quality grapevine varieties requiring less pesticide and adapted to climate change are needed. In perennial species, breeding is a long process which can be speeded up by gaining knowledge about quantitative trait loci linked to agronomic traits variation. However, due to the long juvenile period of these species, establishing numerous highly recombinant populations for high resolution mapping is both costly and time-consuming. Genome wide association studies in germplasm panels is an alternative method of choice, since it allows identifying the main quantitative trait loci with high resolution by exploiting past recombination events between cultivars. Such studies require adequate panel design to represent most of the available genetic and phenotypic diversity. Assessing linkage disequilibrium extent and panel power is also needed to determine the marker density required for association studies.ResultsStarting from the largest grapevine collection worldwide maintained in Vassal (France), we designed a diversity panel of 279 cultivars with limited relatedness, reflecting the low structuration in three genetic pools resulting from different uses (table vs wine) and geographical origin (East vs West), and including the major founders of modern cultivars. With 20 simple sequence repeat markers and five quantitative traits, we showed that our panel adequately captured most of the genetic and phenotypic diversity existing within the entire Vassal collection. To assess linkage disequilibrium extent and panel power, we genotyped single nucleotide polymorphisms: 372 over four genomic regions and 129 distributed over the whole genome. Linkage disequilibrium, measured by correlation corrected for kinship, reached 0.2 for a physical distance between 9 and 458 Kb depending on genetic pool and genomic region, with varying size of linkage disequilibrium blocks. This panel achieved reasonable power to detect associations between traits with high broad-sense heritability (> 0.7) and causal loci with intermediate allelic frequency and strong effect (explaining > 10 % of total variance).ConclusionsOur association panel constitutes a new, highly valuable resource for genetic association studies in grapevine, and deserves dissemination to diverse field and greenhouse trials to gain more insight into the genetic control of many agronomic traits and their interaction with the environment

Whole-genome genotyping of grape using a panel of microsatellite

The use of microsatellite markers in large-scale genetic studies is limited by its low throughput and high cost and labor requirements. Here, we provide a panel of 45 multiplex PCRs for fast and cost-efficient genome-wide fluorescence-based microsatellite analysis in grapevine. The developed multiplex PCRs panel (with up to 15-plex) enables the scoring of 270 loci covering all the grapevine genome (9 to 20 loci/chromosome) using only 45 PCRs and sequencer runs. The 45 multiplex PCRs were validated using a diverse grapevine collection of 207 accessions, selected to represent most of the cultivated Vitis vinifera genetic diversity. Particular attention was paid to quality control throughout the whole process (assay replication, null allele detection, ease of scoring). Genetic diversity summary statistics and features of electrophoretic profiles for each studied marker are provided, as are the genotypes of 25 common cultivars that could be used as references in other studies

Wheat receptor-kinase-like protein Stb6 controls gene-for-gene resistance to fungal pathogen Zymoseptoria tritici

Deployment of fast-evolving disease-resistance genes is one of the most successful strategies used by plants to fend off pathogens. In gene-for-gene relationships, most cloned disease-resistance genes encode intracellular nucleotide-binding leucine-rich-repeat proteins (NLRs) recognizing pathogensecreted isolate-specific avirulence (Avr) effectors delivered to the host cytoplasm. This process often triggers a localized hypersensitive response, which halts further disease development. Here we report the map-based cloning of the wheat Stb6 gene and demonstrate that it encodes a conserved wallassociated receptor kinase (WAK)-like protein, which detects the presence of a matching apoplastic effector and confers pathogen resistance without a hypersensitive response. This report demonstrates gene-for-gene disease resistance controlled by this class of proteins in plants. Moreover, Stb6 is, to our knowledge, the first cloned gene specifying resistance to Zymoseptoria tritici, an important foliar fungal pathogen affecting wheat and causing economically damaging septoria tritici blotch (STB) disease

Résonance magnétique nucléaire de l'azote 15 de composés polyfonctionnels sur l'azote

L'étude par la RMN de l'azote 15 de composés polyfonctionnels sur l'azote montre une très bonne corrélation linéaire entre le déplacement chimique 15N de ces composés et la somme des déplacements chimiques 16N des composés azotés monosubstitués correspondants. L'origine de cette droite, son coefficient directeur, son ordonnée à l'origine et les écarts éventuels sont discutés

Etude par résonance magnétique nucléaire de l'azote 15 de la liaison azote-soufre dans des sulfenamides, sulfinamides et sulfonamides

L'étude par R M N de l'azote 15 de sulfonamides, sulflnamides et sulfénamides a permis de préciser le rôle des facteurs physico- chimiques qui gouvernent la distribution électronique de la liaison azote-soufre. L'influence des substituants de l'atome d'azote ou de soufre sur le déplacement chimique de l'azote 15, ainsi que sur la barrière à la rotation autour de la liaison N – S (AG*) est interprétée sur la base de considérations relatives à l'hybridation de l'atome d'azote, à la conjugaison pπ – dπ et à l'effet d'électronégativité des substituants au niveau des liaisons σ

A network for the management of genetic resources of maize populations in France

International audienc

RFLP diversity and relationships among traditional European maize populations

DOI:10.1007/s00122-002-0903-7International audienc