Identification of Leaf Rust Resistance Genes in Wheat Cultivars Produced in Kazakhstan

Leaf rust, caused by Puccinia recondita f. sp. tritici, is one of the major diseases of wheat in Kazakhstan. To effectively use leaf rust resistance genes (Lr), it is important for breeders to know the resistance genotype in current cultivars. In this study, 30 winter wheat entries grown and/or produced in Kazakhstan were investigated using molecular markers to determine the presence and absence of eight important Lr genes. Molecular screening of these genotypes showed contrasting differences in the frequencies of these genes. Among the 30 entries, 17 carried leaf rust resistance gene Lr1, six had Lr26 and Lr34, and Lr10 and Lr37 were found in three cultivars. Two single cultivars separately carried Lr19 and Lr68, while Lr9 was not detected in any genotypes in this study. Field evaluation demonstrated that two of the most frequent two genes (Lr1 and Lr26) to be ineffective. While Lr34 provided some protection, the remaining effective Lr genes were found only in few genotypes: Lr37 occurred in Kazakh genotypes L-1090 and Krasnovodapadskaya 210 and in the US cultivar Madsen; Lr19 and Lr68 were likely present only in Russian and Kazakh cultivars, Pallada and Yegemen, respectively. The highest resistance over three years of leaf rust testing was found in Kazakh cultivars, Karasay, Krasnovodapadskaya 210, L-1090, Arap and Yegmen, foreign cultivars Madsen, Pallada and the control Parula (Lr68). Data may assist breeders to incorporate effective Lr genes into new cultivars.