The wheat homolog of putative nucleotide-binding site–leucine-rich repeat resistance gene TaRGA contributes to resistance against powdery mildew

Powdery mildew, one of the most destructive wheat diseases worldwide, is caused by Blumeria graminis f. sp. tritici ( Bgt ), a fungal species with a consistently high mutation rate that makes individual resistance ( R ) genes ineffective. Therefore, effective resistance-related gene cloning is vital for breeding and studying the resistance mechanisms of the disease. In this study, a putative nucleotide-binding site–leucine-rich repeat (NBS-LRR) R gene ( TaRGA ) was cloned using a homology-based cloning strategy and analyzed for its effect on powdery mildew disease and wheat defense responses. Real-time reverse transcription-PCR (RT-PCR) analyses revealed that a Bgt isolate 15 and salicylic acid stimulation significantly induced TaRGA in the resistant variety. Furthermore, the silencing of TaRGA in powdery mildew-resistant plants increased susceptibility to Bgt15 and prompted conidia propagation at the infection site. However, the expression of TaRGA in leaf segments after single-cell transient expression assay highly increased the defense responses to Bgt15 by enhancing callose deposition and phenolic autofluorogen accumulation at the pathogen invading sites. Meanwhile, the expression of pathogenesis-related genes decreased in the TaRGA -silenced plants and increased in the TaRGA -transient-overexpressing leaf segments. These results implied that the TaRGA gene positively regulates the defense response to powdery mildew disease in wheat.