Wheat leaf rust caused by Puccinia triticina (Pt) is an epidemic fungal disease widely distributed worldwide, posing a serious threat to the quality and yield of wheat. Planting resistant cultivar is the most economical, environmentally friendly and effective method to manage this disease. So far, a total of 80 leaf rust resistance genes have been identified and mapped, while only few genes keep the resistance to the present races in Chinese rust environments. Therefore, it is of great significance to identify and clone the new resistance gene for development leaf rust resistant wheat variety.

In the present study, we mapped one consistently leaf rust adult plant resistance locus on chromosome 6BL from four durum wheat RIL populations, named as QLr.cim-6BL. The overlapped genetic interval was narrowed to 131 kb and there were only two high-confidence genes according to the reference genome. The candidate G1 gene showed sequence difference between resistant and susceptible parents, while the sequence of candidate G2 was the same between two parents. Thus, we used virus induced gene silencing (VIGS) technology to silence G1 gene, the leaf rust severity of single gene line Atred#2+QLr.cim-6BL was significantly higher than the check (without silencing treatment). In addition, we also verity the function of G1 in susceptible receptor KN199 by Agrobacterium transgenic. The leaf rust severity of transgenic T2 plants showed significantly lower than the negative checks. Thus, we confirm that G1 should be the QLr.cim-6BL and it encodes the RPM1 protein that is a typical disease related gene. In addition, we also found G1 interacted gene (R1) by using yeast two-hybrid method and confirmed it by bimolecular fluorescence complementation (BiFC). Recently, we introduced QLr.cim-6BL into common wheat YM18 by backcrossing to develop new leaf rust resistant wheat germplasm as this gene was not present in bread wheat based on our germplasm screening result. This study provides new resistance gene and new genetic resources for improvement of wheat leaf rust resistance in bread wheat.