MAP kinases phosphorylate rice WRKY45

Abstract

WRKY45 transcription factor is a central regulator of disease resistance mediated by the salicylic acid (SA) signaling pathway in rice. SA-activated WRKY45 protein induces the accumulation of its own mRNA. However, the mechanism underlying this regulation is still unknown. Here, we report three lines of evidence showing that a mitogen-activated protein kinase (MAPK) cascade is involved in this regulation. An inhibitor of MAPK kinase (MAPKK) suppressed the increase in WRKY45 transcript level in response to SA. Two MAPKs, OsMPK4 and OsMPK6, phosphorylated WRKY45 protein in vitro. The activity of OsMPK6 was rapidly upregulated by SA treatment in rice cells. These results suggest that WRKY45 is regulated by MAPK-dependent phosphorylation in the SA pathway.

Keywords: :

• rice
• disease resistance
• MAPK
• salicylic acid
• phosphorylation
• proteasome

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

Acknowledgments

This work was supported by a grant from the Japanese Ministry of Agriculture, Forestry and Fisheries (Genomics for Agricultural Innovation, GMA0001 and PMI0008).