Genome-wide analysis of wall associated kinase (WAK) gene family in barley.

In plants, wall associated kinases (WAKs) form a unique subfamily of receptor like-kinases (RLKs). In Arabidopsis thaliana, WAK-RLKs are known to regulate biotic stress, cell expansion, and metal tolerance, but their detailed characterization in barley is lacking. In this study, we identified a total of 91 WAK genes in the barley genome and classified them into five groups. Evolutionary analysis of HvWAKs with AtWAKs revealed their species-specific expansion. The maximum number (19 to 20) of WAK genes were located on chromosomes 3, 5 and 6. WAK proteins exhibited similar types of motif distribution in their group. Characterization of a Ds transposon insertion mutant of the wak1 revealed differences in the root length. Further, HvSPL23 transcription factor was identified as a positive co-expressing gene with HvWAK1, suggesting its possible upstream regulator. Taken together, our study provides a base for the functional characterization of WAK family members in the future.