The cysteine-rich receptor-like kinase TaCRK3 contributes to defense against Rhizoctonia cerealis in wheat.

Sharp eyespot, caused by the necrotrophic fungal pathogen Rhizoctonia cerealis, is a devastating disease of bread wheat (Triticum aestivum). However, the molecular mechanisms underlying wheat defense against Rhizoctonia cerealis are still largely unknown. In this study, we identified a novel cysteine-rich receptor-like kinase (CRK)-encoding gene, designated as TaCRK3, through comparative transcriptomic analysis, and investigated its defence role against Rhizoctonia cerealis. TaCRK3 transcriptional abundance was significantly elevated by R. cerealis and exogenous ethylene treatments. Silencing of TaCRK3 significantly compromised resistance to R. cerealis and repressed expression of an ethylene biosynthesis enzyme-encoding gene ACO2 and a subset of defence-associated genes in wheat, whose transcript levels are up-regulated by ethylene stimulus. TaCRK3 protein was localized at the plasma membrane in wheat. Noticeably, both the heterologously-expressing TaCRK3 protein and its partial peptide harboring two DUF26 domains could inhibit growth of R. cerealis mycelia. These results suggest that the TaCRK3 mediates wheat resistance to R. cerealis through direct-antifungal activity and heightening the expression of defence-associated genes in the ethylene signaling pathway, and that its DUF26 domains are required for the antifungal activity of TaCRK3. This study provides a promising gene for breeding wheat varieties with resistance to R. cerealis.