ABSTRACT Leaf rust, caused by Puccinia triticina ( Pt ), is one of the most prevalent wheat diseases worldwide, leading to substantial yield losses and reduced grain quality. Understanding the genetic basis of resistance and the diversity of leaf rust resistance ( Lr ) genes is crucial for effective disease management. In the present study, 32 Iranian wheat cultivars and 36 near isogenic lines were evaluated against seven Pt races at the seedling stage under greenhouse conditions. Additionally, the presence of the genes Lr10 , Lr19 , Lr24 and Lr37 was investigated using specific molecular markers. Phenotypic evaluation of genotypes revealed a wide range of infection types, varying from resistant ‘0; = ’ to highly susceptible ‘4’. ‘Pishtaz’, ‘Golestan’ and ‘Rasool’ were the most resistant cultivars. Molecular marker analysis identified the presence of Lr10 , Lr24 and Lr37 , either singly or in combination in 23 cultivars, whereas Lr19 was not detected in any genotype. The gene Lr24 was the most frequently occurring gene (59.38%), followed by Lr10 (53.12%) and Lr37 (43.75%). Notably, cultivars with identical Lr gene combinations often exhibited contrasting infection types, indicating a complex genotype–phenotype relationship and suggesting the involvement of epistatic interactions, uncharacterized resistance loci and local pathogen adaptation. Overall, although Lr24 emerged as the major contributor to leaf rust resistance in the studied germplasm, the absence of Lr19 highlights the need for incorporating additional resistance sources in breeding programs. These findings emphasise the need to broaden the resistance gene pool and deploy diverse genes to enhance the durability of leaf rust resistance in Iranian wheat cultivars.
Dorostkar et al. (Sun,) studied this question.