Characterization of a Receptor-Like Kinase Involved in the Defense Response in Rice

Abstract

Microarray analysis of the chitin elicitor-treated rice cells revealed the enhanced expression of a receptor-like kinase gene, of which extracellular domain showed a high homology with a PR protein. The expression of this gene was induced by chitin oligosaccharides depending on their size and structure. Cycloheximide, a protein synthesis inhibitor, also induced the expression of the gene in the absence of the elicitor. The receptor-like kinase was shown to be localized in the plasma membrane by western blotting and microscopic analysis of the GFP-fusion protein. In a whole plant, the strongest expression was found in the leaves. Intracellular domain of the receptor-like kinase expressed in E.coli showed a strong auto-phosphorylation activity but those proteins with mutations for putative active site amino acid residues showed no or weak activity. Analysis of biological function of the receptor-like kinase is now underway by using over-expressor as well as knock-down cell lines.