Identification of Resistant Germplasm and Detection of Genes for Resistance to Powdery Mildew and Leaf Rust from 2,978 Wheat Accessions.

Powdery mildew and leaf rust, caused by f. sp. and , respectively, are widespread diseases of wheat worldwide. The use of resistant cultivars is considered the most economical, environment-friendly, and effective method to control these diseases. In the present study, a collection of 2,978 wheat accessions consisting of 1,394 advanced breeding lines, 1,078 Chinese cultivars, 291 introduced cultivars, 132 lines containing alien chromosomes, and 83 landraces was tested for reactions to powdery mildew and leaf rust. The results indicated that 659 wheat accessions (22.1%) were highly resistant to a widely prevalent f. sp. isolate, E09, at the seedling stage, and 390 were consistently resistant to the mixture of f. sp. isolates at the adult plant stage. Meanwhile, 63 accessions (2.1%) were highly resistant to leaf rust at the adult plant stage, of which 54 were resistant to a predominant and highly virulent race, THTT, at the seedling stage. Notably, 17 accessions were resistant to both powdery mildew and leaf rust. To detect known genes for resistance to powdery mildew and leaf rust, these accessions were tested with gene-specific or tightly linked markers for seven powdery mildew genes ( genes; , , , , , , and ) and 10 genes (, , , , , , , , , and ). Of the 659 powdery mildew-resistant accessions, 328 might carry single genes and 191 carry combined genes. was detected at the highest frequency of 59.6%, followed by , , , , and , whereas was not detected. In addition, 139 accessions might contain unknown genes different from those tested in this study. In the 63 accessions resistant to leaf rust, four leaf rust genes ( genes; , , , and ) were detected in 41 accessions singly or in combination, whereas six genes (, , , , , and ) were not detected. Twenty-two accessions might contain unknown genes different from those tested in this study. This study not only provided important information for rationally distributing resistance genes in wheat breeding programs, but also identified resistant germplasm that might have novel genes to enrich the diversity of resistance sources.