Durable and broad spectrum disease resistance to bacterial blight and bacterial leaf streak of rice
A. BOSSA-CASTRO (1), E. Delorean (2), C. Raghavan (3), C. Tekete (4), A. Dereeper (5), K. Dagno (6), O. Koita (4), G. Mosquera (7), H. Leung (3), V. Verdier (5), J. Leach (2) (1) Colorado State University, U.S.A.; (2) Colorado State University, U.S.A.; (3) International Rice Research Institute (IRRI), Philippines; (4) Université des Sciences Techniques et Technologiques, Faculté des Sciences et Techniques, LBMA, Mali; (5) IRD, Cirad, Univ. Montpellier, Interactions Plantes Microorganismes Environnement, France; (6) Institute of Rural Economy, Plant Protection, Mali; (7) International Center for Tropical Agriculture (CIAT), Colombia

Mayor losses in rice production are caused by bacterial blight (BB) and bacterial leaf streak (BLS), caused by Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc), respectively. The aim of this study was to identify sources of durable and broad spectrum resistance effective against BB and BLS. We used an indica rice Multi-parent Advanced Generation Inter-Cross (MAGIC) population, a novel mapping resource that allows high resolution detection for quantitative trait loci (QTL). At the eighth selfed generation (S8), a random subset of lines was selected and genotyped by sequencing, along with the founders. To identify QTL conferring broad spectrum resistance, the S8 subset and founders were phenotyped with Xoc and Xoo strains in the greenhouse. In parallel, the S8 subset was phenotyped in the field in Mali with several Xoc and Xoo strains from different genetic backgrounds. To identify potentially durable resistance, the subset was also screened with Xoo containing TAL7b, a transcription activator like (TAL) virulence effector that is common to several Xoo strains. Genome-wide association and interval mapping analysis were performed to map disease resistance QTL. We identified novel and common disease resistant QTL effective against Xoc and Xoo, suggesting potential sources of broad-spectrum resistance. We also identified resistance to TAL7b; as TAL7b is a virulence factor, we hypothesize that this resistance will be durable. Future studies will characterize the QTL, and determine if they confer broad spectrum and/or durable resistance. Resistance genes targeting several strains and specifically effective against virulence enhancing TALs may offer increased durability in the field.

Abstract Number: S2-3
Session Type: Special Session