Evaluation of Resistance to Leaf Rust in Bread Wheat Landraces and Commercial Cultivars Under Field Conditions and By Using Molecular Markers Linked to Lr34/Yr18/Sr57 Genes M.

Leaf rust is one of the most important rusts diseases of wheat in the world, and its potential impact on wheat yield losses has always been considered significant in many regions. Identifying and using resistance genes against fungal diseases in wheat genetic resources is one of the most effective approaches to introduce new sources of resistance to improved commercial wheat cultivars. In this study, 82 bread wheat landraces and commercial cultivars from different parts of the world were evaluated under field conditions and by using molecular markers assay. In the field nursey, 56 genotypes showed susceptible reaction, 22 genotypes were moderately susceptible, and four genotypes showed resistance or immunity to leaf rust. Reactions varied from moderately susceptible to immunity in different genotypes such as genotypes originated from Iran, Nepal, Pakistan, Turkey, and India. Most of these genotypes were landraces which indicates the importance of studying wheat genetic resources. The results of the Lr34 molecular assay using csLV34, caSNP4 and caSNP12 markers were identical, and showed the same pattern of resistance allele in six genotypes. In molecular assay, cultivars from Iran with CIMMYT origin and genotypes from India and Turkey had effective alleles of Lr34 gene. The observed genetic diversity and frequency of genotypes with resistance genes in this study can be useful to enhance germplasm for leaf rust resistance in bread wheat breeding programs in Iran.