Wall-associated Receptor Kinase and The Expression Profiles in Wheat Responding to Fungal Stress

Abstract

Cell wall-associated kinases (WAKs), which are encoded by conserved gene families in plants, are crucial for development and responses to diverse stresses. However, the wheat (Triticum aestivum L.) WAKs have not been systematically classified, especially those involved in protecting plants from disease. Here, we classified 129 WAK proteins (encoded by 232 genes) and 75 WAK-Like proteins (WAKLs; encoded by 109 genes) into four groups, via a phylogenetic analysis. An examination of protein sequence alignment revealed diversity in the GUB-domain of WAKs structural organization, but it was usually characterized by a PYPFG motif followed by CxGxGCC motifs, while the EGF-domain was usually initiated with a YAC motif, and eight cysteine residues were spliced by GNPY motif. The expression profiles of WAK-encoding homologous genes varied in response to Blumeria graminis f. sp. tritici (Bgt), Puccinia striiformis f. sp. tritici (Pst) and Puccinia triticina (Pt) stress. A quantitative real-time polymerase chain reaction (qRT-PCR) analysis proved that TaWAK75 and TaWAK76b were involved in wheat resistance to Bgt. This study revealed the structure of the WAK-encoding genes in wheat, which may be useful for future functional elucidation of wheat WAKs responses to fungal infections.