Fine mapping and candidate gene identification of the stripe rust resistance gene Yr83 using mutated wheat-rye...

The stripe rust resistance gene Yr83 from rye chromosome 6R in a wheat background was mapped to a physical region of 875.23-881.29 Mb on 6RL using radiation-induced deletions generated from a T6DS.6RL translocation line. The comparative transcriptomic analysis among different wheat-rye 6R derived lines indicated that the target candidate disease resistance gene was Yr83. The long arm of chromosome 6R (6RL) of triticale T-701, derived from "Merced" rye (Secale cereale L.), carries gene Yr83 that is currently effective against stripe rust races in both China and Australia. The chromosomal location of Yr83 on the 6RL region had been further narrowed down to enable gene isolation. Different types of 6RL deletions and translocations derived from the T6DS.6RL translocation line R476 were established through gamma radiation-induced populations and were subsequently screened by non-denaturing fluorescence in situ hybridization (ND-FISH), molecular markers and stripe rust testing. We found that the terminal region spanning 875.23-881.29 Mb of 6RL carries Yr83, conferring resistance at both seedling and adult plant stages. The susceptible wheat-6R lines from different rye or triticale origins were developed and compared with the Yr83 lines by transcriptomic analysis. The results indicated that a target nucleotide-binding site and leucine-rich repeat (NBS-LRR)-like resistance protein gene, SECCE6Rv1G0452990, is the most likely candidate gene for Yr83. The small segment translocations induced from the T6DS.6RL lines, along with targeted specific molecular markers, will provide valuable germplasm resources for the precise utilization of Yr83 gene in wheat breeding for rust resistance.