Abstract
Lipid signaling pathways play pivotal roles in plant defense reactions. In Arabidopsis, the SSI2 mutant defective in ACP-fatty acid desaturase gene shows resistance to Peronospora parasitica, Pseudomonas syringae and Cucumber mosaic virus. In this study, we characterized a rice SSI2-homolog, OsSSI2, in rice disease resistance.
RNAi-mediated OsSSI2-knockdown (OsSSI2-kd) rice plants displayed spontaneous lesion formation, slight growth delay, constitutive expression of PR genes and BTH-inducible WRKY genes, and enhanced resistance to blast disease. These results suggest that the products of OsSSI2 reaction is involved in negative regulation of defense reaction in rice. OsSSI2 expression was highest in young leaves and gradually downregulated as the leaves matured, which could be relevant to adult-plant resistance of rice. Analyses of salicylic acid content and fatty acid composition in OsSSI2-kd rice plants, as well as transcript profiling of them, are in progress.
