Rice Wall-Associated Protein Kinase OsWAK12 Modulates Primary Root and Root Hair Via Involving in Auxin Pathway

Wall-associated protein kinases (WAKs), as one subfamily of the receptor-like protein kinases (RLKs) in plants, have been shown to be required for multiple biological processes including cell elongation regulation. However, little information is available about the roles of plant WAKs in root morphogenesis regulation. Here, a rice WAK subfamily member, OsWAK12, was isolated and confirmed to be involved in root morphogenesis regulation. OsWAK12 is mainly highly expressed in both young and mature roots in rice. Phenotypic analysis showed that the Cas9-edited mutants of OsWAK12 exhibited a shorter primary root, shorter root hair length and less root hair density at seedling stage than wild type Nipponbare. Moreover, OsWAK12 overexpression in rice displays reverse phenotypes compared to these results of the Cas9-edited mutants of OsWAK12. Further analysis revealed that OsWAK12 expression was significantly induced by the auxin indoleacetic acid (IAA) and the sensitivity of primary root and root hairs to IAA and endogenous IAA content were altered in the Cas9-edited and overexpression mutants of OsWAK12. The sensitivity of the Cas9-edited mutants of OsWAK12 to IAA was decreased, contrary to the results of its overexpression mutants. Summarily, these results suggest that OsWAK12 plays important roles in rice root morphogenesis via the auxin pathway.