Abstract
BTH, a plant activator, protects plants from diseases by activating salicylic acid (SA) signaling pathway in Arabidopsis and tobacco. On the other hand, little is known about SA signaling pathway in rice. Our previous microarray analysis revealed four BTH-responsive WRKY transcription factor genes. Here we report functional characterization of one of them, OsWRKY45.
OsWRKY45 knockdown (RNAi) rice showed reduction of BTH-inducible resistance to rice blast fungus. Moreover, OsWRKY45-overexpressing (OsWRKY45-ox) rice showed enhanced resistance to the fungus. These results indicates that OsWRKY45 plays a critical role in BTH-inducible rice blast resistance. OsWRKY45-ox plants showed upregulation of PR-1b and PR-2 genes when grown in a growth chamber, whereas they showed no upregulation when grown in a greenhouse. Only small adverse effects on growth were observed in a growth chamber, whereas no such effects in a greenhouse. We discuss these results with respect to 'potentiation', a proposed mode of BTH action.
