Genetic Characteristics and Linkage of Virulence Genes of the <i>Puccinia striiformis</i> f. sp. <i>tritici</i> TSA-6 Isolate to <i>Yr5</i> Host Resistance

Abstract

To understand the inheritance of the TSA-6 <i>Puccinia striiformis</i> f. sp. <i>tritici</i> (<i>Pst</i>) isolate that is virulent to <i>Yr5</i> and was recently detected in China, we analyzed avirulence and virulence of 120 selfed progeny lines from <i>Berberis shensiana</i>. The results showed that the TSA-6 isolate is virulent against the <i>Yr5</i> resistance gene, and overall progeny lines were categorized into 73 virulence phenotypes (VPs); of these, 72 VPs differed from the isolate TSA-6, and only one VP, including three progeny, was identical to the parental isolate. The analyses indicated that the TSA-6 isolate is homozygous for avirulence at the <i>Yr10</i>, <i>Yr15</i>, and <i>Yr26</i> resistance loci and virulence at the <i>YrA</i> resistance locus. The TSA-6 isolate is heterozygous for avirulence at the <i>Yr2</i>, <i>Yr3</i>, <i>Yr5</i>, <i>Yr7</i>, and <i>Yr8</i> resistance loci, which are controlled by a dominant/recessive relationship. The <i>Yr1</i>, <i>Yr6</i>, <i>Yr9</i>, <i>Yr17</i>, <i>Yr27</i>, <i>Yr25</i>, <i>Yr28</i>, <i>Yr29</i>, <i>Yr32</i>, <i>YrTr1</i>, and <i>YrSP</i> resistance loci are governed by two complementary dominant/recessive genes. Avirulence against heterozygous <i>Yr4</i>, <i>Yr43</i>, <i>Yr44</i>, <i>Yr76</i>, and <i>YrExp2</i> resistance loci is regulated by a dominant and recessive or a dominant and suppressor gene pair. In total, 117 multilocus genotypes were detected at 24 KASP-SNP marker loci among the 120 progenies. Using these marker loci, we constructed a linkage map with a genetic distance interval spanning 624.5 cM. Quantitative trait loci corresponding to phenotypic segregation for virulence at 20 <i>Yr</i> resistance loci in addition to the <i>Yr1</i> resistance locus were identified. These results facilitate our understanding of <i>Pst</i> virulence evolution and simplify breeding of wheat cultivars with effective resistance to wheat stripe rust.