Characterization of the Powdery Mildew Resistance Gene in the Elite Wheat Cultivar Jimai 23 and Its Application in Marker-Assisted Selection

Abstract

Powdery mildew infection of wheat (<i>Triticum aestivum</i> L.), caused by <i>Blumeria graminis</i> f. sp. <i>tritici</i> (<i>Bgt</i>), is a destructive disease that threatens yield and quality worldwide. The most effective and preferred means for the control of the disease is to identify broad-spectrum resistance genes for breeding, especially the genes derived from elite cultivars that exhibit desirable agronomic traits. Jimai 23 is a Chinese wheat cultivar with superior agronomic performance, high-quality characteristics, and effective resistance to powdery mildew at all growth stages. Genetic analysis indicated that powdery mildew resistance in Jimai 23 was mediated by a single dominant gene, tentatively designated <i>PmJM23</i>. Using bulked segregant RNA-Seq (BSR-Seq), a series of markers was developed and used to map <i>PmJM23. PmJM23</i> was then located at the <i>Pm2</i> locus on the short arm of chromosome 5D (5DS). Resistance spectrum analysis demonstrated that <i>PmJM23</i> provided a broad resistance spectrum different from that of the documented <i>Pm2</i> alleles, indicating that <i>PmJM23</i> is most likely a new allele of <i>Pm2</i>. In view of these combined agronomic, quality, and resistance findings, <i>PmJM23</i> is expected to be a valuable resistance gene in wheat breeding. To efficiently use <i>PmJM23</i> in breeding, the closely linked markers of <i>PmJM23</i> were evaluated and confirmed to be applicable for marker-assisted selection (MAS). Using these markers, a series of resistant breeding lines with high resistance and desirable agronomic performance was selected from the crosses involving <i>PmJM23</i>, resulting in improved powdery mildew resistance of these lines.