Molecular Screening and Resistance Evaluation of American Wheat Cultivars to Chinese Stripe Rust Races

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the major diseases of wheat in China. In order to asses the resistance levels and existing Yr genes among 59 wheat cultivars (lines) from the Pacific Northwest (PNW) of the United States, to provide resistance resources for genetic improvement of wheat stripe rust resistance in China, 59 wheat cultivars (lines) from PNW of the United States were infected by 3 mixed races of predominant Chinese stripe rust races CRY31, CRY32, and CRY33 to evaluate their resistance at seedling and adult plant stages, and screened with molecular markers tightly linked to currently effective all-stage resistance genes Yr10, Yr15 and adult plant resistance genes Yr18, Yr39. Of 59 American cultivars (lines), five cultivars (lines), Expresso, 02W50076, ACS52610, WA008012, and WA00801833, had all-stage resistance, showing resistance to mixed races of CRY31, CRY32, and CRY33 at both seedling and adult plant stages. 33 cultivars (lines) had adult plant resistance, only showing resistance to stripe rust at adult stage. Based on the molecular screening, none of the 59 PNW cultivars (lines) had the polymorphic bands of linked markers to Yr10. There were 12, 33 and 29 cultivars (lines) which had polymorphic bands of linked markers to Yr15, Yr18 and Yr39, accounting for 20, 55 and 49% of the 59 PNW cultivars (lines), respectively. All these results suggested that Yr15, Yr18 and Yr39 were widespread among PNW cultivars (cultivars) and could be utilized in Chinese wheat stripe rust resistance breeding.