Identification of the leaf rust resistance genes Lr9, Lr26, Lr28, Lr34, and Lr35 in a collection of Iranian wheat genotypes using STS and SCAR markers

Brown rust or leaf rust is one of the most important diseases of wheat occurring almost in all wheat-producing regions and reduces crop yield. In order to produce resistant cultivars, it is necessary to identify resistance genes in different germplasms and combine them in (a) suitable stock(s). To identify the presence of the leaf rust resistance genes using STS and SCAR markers, 83 Iranian wheat genotypes, Lr near-isogenic lines in Thatcher (positive controls), and the cultivar Thatcher (negative control) were used. After growing plants in the greenhouse, DNA was extracted by SDS method. Following that, polymerse chain reaction was performed for the markers of the resistance genes Lr9, Lr26, Lr28, Lr34, and Lr35 which amplified 1,100, 1,100, 378, 150, and 900 bp bands, respectively. Based on the results, the resistance genes Lr9 and Lr35 were only present in the positive controls. The resistance gene Lr26 was only detected in four cultivars; Arta, Pishtaz, Shiroodi, and Falat, and the gene Lr34 was present in six cultivars (Akbari, Bam, Tajan, Khazar 1, Sistan and Niknezhad). The Lr28 primer amplified a band of the same size in all genotypes even the negative control and therefore the presence/absence of this gene could not be validated. These results indicate the necessity for designing a specific primer for Lr28. In general, only the genes Lr26 and Lr34 were present in some genotypes. The genes Lr9 and Lr35 were not present in this collection and as based on rust surveys, no virulence has been detected for Lr9 and Lr28, so they could be transferred to suitable lines from donor sources.