Abstract
RSOsPR10 (Root Specific Oryza sativa Pathogenesis-Related 10) was identified as the root specific protein induced by drought and salt treatment in rice. The RSOsPR10 shows high similarity to PBZ1/OsPR10a, a PR10 protein induced by probenazole. Expression of RSOsPR10 is regulated at the transcriptional level, and stress-dependent RSOsPR10 expression is induced by ethylene and suppressed by salicylic acid. Since RSOsPR10 expression was induced by exogenously applied jasmonic acid (JA), up-regulation of RSOsPR10 is supposed to be mediated through ethylene-JA closs talk. When RSOsPR10 was over-expressed, the transformed rice showed higher tolerance to drought stress than the wild-type. These suggest that RSOsPR10 acts as an important molecule for stress responses. In the study, we conducted promoter analysis to illuminate mechanisms in regulation of RSOsPR10 expression. Transformant expressing GFP under 0.6 or 1.9kb promoter region of RSOsPR10 was prepared and the expression profile of GFP was observed. In the transgenic plants without stress treatment, the GFP signal was detected in their root and shoot. Moreover, level of GFP signal did not change even after salt-treatment. These suggested that regulatory elements for root-specific expression and stress responsibility are located beyond 1.9kb of RSOsPR10 promoter. We are currently investigating the 3 and 4kb promoter region, in which two possible ethylene responsive elements exist.
