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Virulence of Puccinia triticina and detection of leaf rust resistance genes in different Egyptian wheat genotypes

Abdelrazek Abdelrhim: Minia University

<div>Leaf rust caused by <em>Puccinia triticina</em> is one of the most serious diseases of wheat worldwide. It can cause large reductions in wheat yield; for example, in Egypt, losses may reach 50%. One of the most effective and durable strategies to control leaf rust is breeding for leaf rust resistant cultivars. In Egypt, more up-to-date information is needed about the virulence of <em>P.</em> <em>triticina</em> populations, genetic information about growing wheat cultivars, and sources of effective <em>Lr</em> genes. The aim of this study was to characterize the virulence of Egyptian <em>P.</em> <em>triticina</em> populations and identify effective <em>Lr</em> genes in recent Egyptian bread and durum wheat cultivars, as well as old wheat lines. Using single-gene differentials, we identified virulence phenotypes of 50 <em>P. triticina</em> isolates collected from 10 Egyptian provinces during the 2015-2016 growing season. The highest-frequency virulence phenotypes were TCTTQ (20%) and TFTTQ (18%). Also, using gene postulation assay, <em>Lr16</em>, <em>Lr19</em>, <em>Lr24</em>, <em>Lr36</em>, and <em>Lr51</em> were postulated in several old spring bread wheat lines. SSR and SNP markers were used to detect eight <em>Lr</em> genes in 64 Egyptian wheat genotypes. Of those genes, <em>Lr46</em> was detected in most old and new genotypes, and <em>Lr9 </em>was found in two old lines (L1360-3838 and V-3) and one recent cultivar (Sakha-94), <em>Lr19</em> was detected in 3 old lines and 2 recent cultivars, while <em>Lr21</em>, <em>Lr24</em>, <em>Lr34</em>, and <em>Lr67</em> were mainly found in old genotypes. In contrast, <em>Lr26</em> was detected in 10 genotypes including 2 old lines.</div>