Postulation of leaf rust resistance genes in Iranian wheat cultivars and breeding lines

Knowledge of the number and identity of the leaf rust resistance genes in wheat breeding material is essential for maximizing resistance in future-bred cultivars. The objective of this study was to test for seedling resistance genes to Puccinia triticina potentially present in 36 Iranian wheat cultivars and breeding lines, using 13 prevalent isolates of P. triticina. Eight known genes and some unidentified genes were postulated for resistance to leaf rust in 21 Iranian wheat genotypes. The most frequently occurring genes in Iranian wheat genotypes were Lr1 (71%), followed by Lr13 (62%), Lr10 (43%), Lr26 (38%), Lr23 (19%) and Lr17 (10%). Seven genotypes lacked any detectable seedling resistance gene and two cultivars along with three breeding lines were resistant to all isolates used in the study. It is concluded that there was little variation in the Lr genes carried by wheat cultivars commercially grown in Iran. Therefore, strategies for deploying resistance genes to prolong effective disease resistance are suggested.