Whole genome analysis and prediction of the quantitative disease resistance against Verticillium wilt
M. MAZURIER (1), A. Sbeiti (1), S. Benameur (1), M. Tardin (2), M. Gras (2), T. Tatarinova (3), S. Nuzhdin (3), P. Marjoram (3), M. Rickauer (1), C. Ben (1), L. Gentzbittel (1) (1) Université Fédérale de Toulouse, France; (2) Société R2n - Groupe RAGT, France; (3) University of Southern California, U.S.A.

Disease resistance conditioned by multiple genes of small effects is one of the most durable resistance in crop breeding. The interaction between the legume model plant Medicago truncatula (Mt) and the root pathogen Verticillium alfalfae (Va) is studied to investigate the genetic mechanisms involved in quantitative disease resistance (QDR) against Verticillium wilt. Disease progress monitored in 242 inoculated Mt ecotypes highlighted a large biodiversity of the response to Va. A genome wide association study (GWAS) of this response pinpointed several quantitative trait loci (QTL) on chr1, 7 and 8. Five candidate genes are localized under a previously described major QTL for Va resistance on chr7. Among them, 2 genes were found expressed in Mt roots in response to Va. Their functional validation is under way. Since the identified QTLs do not explain the entire phenotype, we developed a new whole genome approach. The Mt species was divided in 8 populations and the genome admixture components of each accession were reported. Variation in genome admixture proportion explains most of disease phenotypic variation. By inoculating 71 accessions predicted to be susceptible or resistant based on their population origin, we demonstrated that this approach allows accurate genome-based prediction of QDR against Va in Mt. Both genetic approaches appear useful and complementary to understand QDR in plants and to develop new breeding strategies for resistance to Verticillium wilt.

Abstract Number: P11-371
Session Type: Poster