A Novel Wall-Associated Kinase TaWAK-5D600 Positively Participates in Defense against Sharp Eyespot and Fusarium Crown Rot in Wheat.

Sharp eyespot and Fusarium crown rot, mainly caused by soil-borne fungi Rhizoctonia cerealis and Fusarium pseudograminearum , are destructive diseases of major cereal crops including wheat ( Triticum aestivum ). However, the mechanisms underlying wheat-resistant responses to the two pathogens are largely elusive. In this study, we performed a genome-wide analysis of wall-associated kinase (WAK) family in wheat. As a result, a total of 140 TaWAK (not TaWAKL ) candidate genes were identified from the wheat genome, each of which contains an N-terminal signal peptide, a galacturonan binding domain, an EGF-like domain, a calcium binding EGF domain (EGF-Ca), a transmembrane domain, and an intracellular Serine/Threonine protein kinase domain. By analyzing the RNA-sequencing data of wheat inoculated with R. cerealis and F. pseudograminearum , we found that transcript abundance of TaWAK-5D600 ( TraesCS5D02G268600 ) on chromosome 5D was significantly upregulated, and that its upregulated transcript levels in response to both pathogens were higher compared with other TaWAK genes. Importantly, knock-down of TaWAK-5D600 transcript impaired wheat resistance against the fungal pathogens R. cerealis and F. pseudograminearum , and significantly repressed expression of defense-related genes in wheat, TaSERK1 , TaMPK3 , TaPR1 , TaChitinase3 , and TaChitinase4 . Thus, this study proposes TaWAK-5D600 as a promising gene for improving wheat broad resistance to sharp eyespot and Fusarium crown rot (FCR) in wheat.