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High-density Mapping of an Adult-plant Stripe Rust Resistance Gene Yrbai in Wheat Landrace Baidatou Using the Whole Genome DArT-seq and SNP Analysis

Qiang Li: College of Plant Protection, Northwest A&F University

<div>Stripe rust, caused by the biotrophic fungus <em>Puccinia</em> <em>striiformis</em> f. sp. <em>tritici</em> (<em>Pst</em>), is one of the most widespread and destructive wheat diseases worldwide. Growing resistant cultivars is an effective approach for controlling of this disease. However, because host resistance genes were easily overcome by new virulent <em>Pst</em> races. There is a continuous demand for identifying new effective wheat stripe rust resistance genes and develop closely linked markers for marker-assisted selection (MAS). Baidatou, an old Chinese wheat landrace, has been grown several decades in Longnan region, Gansu Province, where stripe rust epidemics are frequent and severe. In our previous study, a single dominant gene <em>YrBai</em> in Baidatou was identified to control the adult-plant resistance (APR) to Chinese prevalent <em>Pst</em> race CYR33. And the gene was located on wheat chromosome 6DS by four polymorphic SSR and two SRAP markers, with the genetic distances of two closely linked markers 3.6 and 5.4 cM, respectively. To further confirm the APR gene in Baidatou and construct the high-density map for the resistance gene, adult plants of F<sub>1</sub>, F<sub>2</sub>, F<sub>3</sub><sub> </sub>and F<sub>5:6</sub><sub> </sub>populations were still inoculated with CYR33 at Yangling field, Shaanxi Province during 2014-2015 and 2016-2017 crop seasons, respectively. The results indicated that a single dominant gene confers the APR to <em>Pst</em> race CYR33 in Baidatou. Using DArT and SNP markers, the APR gene <em>YrBai</em> was further located in 0.8 cM region on wheat chromosome 6D. These closely linked markers developed in this study should be useful for MAS for Baidatou in crop improvement and map-based clone this gene.</div>