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

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.