Stripe rust caused by Puccinia striiformis f. sp. tritici and powdery mildew caused by Blumeria graminis f. sp. tritici are devastating diseases of wheat worldwide. Exploration of new disease-resistant genes from cultivated wheat and wild relatives are the most effective means of reducing the amounts of fungicides applied to combat these diseases. Thinopyrum scirpeum (2n = 4x = 28, EEEE) is an important promising reservoir of useful genes, including stripe rust and powdery mildew resistance, and may be useful for increasing wheat disease resistance. Here, we characterize a novel wheat-Th. scirpeum disomic substitution line, K16-730-3, and chromosome-specific markers were developed that can be used to trace the Th. scirpeum chromosome or chromosome segments transferred into wheat. Genomic in situ hybridization and fluorescence in situ hybridization analyses indicated that K16-730-3 is a new 4E (4D) chromosomal substitution line. Evaluation of seedling and adult disease responses revealed that K16-730-3 is resistant to stripe rust and powdery mildew. In addition, no obvious difference in grain yield was observed between K16-730-3 and its wheat parents. Genotyping-by-sequencing analyses indicated that 74 PCR-based markers can accurately trace chromosome 4E, which were linked to the disease resistance genes in the wheat background. Further marker validation analyses revealed that 13 specific markers can distinguish between the E-genome chromosomes of Th. scirpeum and the chromosomes of other wheat-related species. The new substitution line K16-730-3 carrying the stripe rust and powdery mildew resistance genes will be useful as novel germplasm in breeding for disease resistance. The markers developed in this study can be used in marker-assisted selection for increasing disease resistance in wheat.
Keywords: Thinopyrum scirpeum; chromosomal substitution; genotyping by sequencing; powdery mildew; stripe rust.