Expression and promoter analysis of the OsHSP16.9C gene in rice.

Small heat shock proteins (sHSPs) are molecular chaperones important for stress tolerance. In this study, heat induction of a rice sHSP gene OsHSP16.9C is analyzed to understand the molecular mechanisms underlying gene expression regulation in heat shock responses in rice. Promoter deletion analysis of the OsHSP16.9C using the luciferase (LUC) reporter gene in transgenic rice identifies a critical role of a promoter fragment containing an imperfect heat shock element (HSE) in heat induction. HSE was shown to be important for heat induction of AtHSP18.2, a homolog of OsHSP16.9C in Arabidopsis. In addition, the rice OsHSP16.9C promoter confers heat induction of the reporter gene expression in Arabidopsis. These data suggest that the heat induction mechanisms of OsHSP16.9C and AtHSP18.2 are similar in rice and Arabidopsis. The transgenic reporter line generated offers a system to genetically dissect signaling events in heat induction in rice.