Abstract only

Pastor is a CIMMYT wheat line that has quantitative resistance to both leaf rust and stripe rust. It was developed through a breeding program that has a strong focus on incorporating minor, additive genes to confer durable resistance to both diseases. Generational advancement of populations occurs under alternate epidemics of the two pathogens at two field sites in Mexico. An F5 RIL population was developed from Pastor × Avocet. QTL analysis identified 9 loci contributing to stripe rust resistance and 5 loci for leaf rust resistance in Pastor. Interestingly, all 5 leaf rust resistance loci were either linked or pleiotropic with stripe rust QTLs and this is thought to be an outcome of the breeding strategy. Seedling tests identified the moderately effective race-specific resistance gene Yr31 in Pastor, and this gene was the major contributor to overall stripe rust resistance. In the course of the investigation, Yr31 was overcome by the pathogen, but there was still a degree of residual resistance at the locus, along with a minor but significant effect on leaf rust response. Another influential locus was Lr46/Yr29 (1BL) with large and significant effects in all environments. Linked leaf rust and stripe rust loci were also identified on chromosomes 1BS, 6BL and 7BL. Finally a 3BS locus for stripe rust was identified in the region of the Sr2/Yr30 locus. Our results indicate the complex nature of adult plant resistance to the rusts.

Global Wheat Program

Text in English

INT3219|INT0610|INT2833

CIMMYT Staff Publications Collection