Screening of bread wheat germplasm and identification of genetic resources resistant to leaf rust disease

Leaf rust is one of the most important wheat diseases in the world and Iran and the use of resistant cultivars is the most effective tool against this disease, however, the resistance of the cultivars becomes ineffective following a selective pressure on the pathogen, which makes the search for new resistance genetic resources unavoidable. The present study was performed to identify these sources of resistance in wheat germplasm. Therefore, 97 accessions from the bread wheat collection of National Plant Gene Bank of Iran were investigated under natural infection condition at Eraghi-Mahale Research Station, Gorgan, Iran, in 2017-2018. The results showed that 46.4% of the studied accessions had a zero infection coefficient that were selected for evaluation at the seedling stage. Seedling evaluation was performed in greenhouse using four pathotypes with determined virulence-avirulence factors. The results of qualitative and quantitative analyzes grouped the studied accessions into different groups with specific resistance to one or more pathotypes. Comparison of resistance response of the accessions with avirulence/virulence formula in the pathotypes indicated the possibility of presence of Lr14a in the accession 5127. Furthermore, these comparisons revealed the possibility of presence of unknown resistance genes in many of the accessions under study. The results of this study showed the valuable capacity of the bread wheat germplasm to possibly identify new genes and sources of resistance to leaf rust. Therefore, it is suggested that additional research be done to evaluate and screen the bread wheat germplasm.