Characterization of Genes for Durable Resistance to Leaf Rust and Yellow Rust in Cimmyt Spring Wheats

Abstract

Leaf and stripe rusts, caused by Puccinia triticina and P. striiformis, respectively, are globally important fungal diseases that cause significant yield losses in wheat. The objectives of our study were to characterize genetic loci associated with resistance to leaf and yellow rusts by using molecular markers in multiple populations derived from a common susceptible cultivar Avocet crossed with several improved CIMMYT spring wheats. Results obtained from two crosses are presented. Using bulked segregant analysis and partial linkage mapping with AFLPs, SSRs and RFLPs, we identified six independent loci that contributed to adult plant resistance (APR) to the two rust diseases in Avocet x Pavon76 population. The loci identified on chromosomes 1BL, 4BL and 6AL influenced resistance to both yellow and leaf rust commonly whereas two additional loci, on chromosomes 3BS and 6BL, had effects on yellow rust only. In Avocet x Parula population, four independent loci were identified. The loci on chromosomes 1BL and 7DS had effects commonly for the two rust diseases, whereas the locus on chromosome 7B had effects only on leaf rust and the locus on chromosome 3BS had effects only on yellow rust. A single chromosome recombinant line population was used to map the Lr46/Yr29 locus as a simply inherited Mendelian trait.