研究期間：10208~10307;Sugars are evolutionarily conserved signaling molecules that regulate various genes involved in developmental stages and adaption of abiotic stresses. Cross-talk between sugar and abiotic stress signaling has been evidenced at transcriptional level. However, little is understood about the mechanism of mRNA degradation, which is also important for regulation of gene expression in sugar-abiotic stress signaling networks. It is known that deadenylation of poly(A) tail is the first and rate-limiting step during mRNA degradation. And therefore CCR4-CAF1complex with deadenylase activity is proposed to play a prominent role in mRNA degradation. However, physiological functions of CCR-4CAF1 are still not clear. We identified the CAF1 genes from maize and rice, ZmCAF1s and OsCAF1s, respectively. Our recent evidences suggested that plant CAF1s have deadenylase activity and function at the first step of mRNA degradation in plants. Further investigations are required to elucidate specific roles of plant CAFs in mRNA degradation of genes in sugar-abiotic stress signaling networks. Therefore, both loss- and gain-of function approaches for these CAFs will be used and further microarray analysis will be applied in this proposed research. The following three specific aims are intended to study OsCAFs. 1. To demonstrate of biological functions of OsCAF1s in sugar signaling transduction pathway. 2. To address whether using mRNA degradation to resist stressful environmental conditions is practical in rice through manipulation of activities of OsCAF1H and OsCAF1B in transgenic rice for stress tolerance. 3. To analyze in vitro RNase activities of OsCAF1s by recombinant protein approach in E.coli. In addition to our understanding about transcriptional regulation in sugar-abiotic stress signaling networks, we will have more clear view in post-transcriptional regulation after combining results from these proposed works. Through knowledge of both transcriptional and post-transcriptional gene regulation in rice, we are able to design a practical genetic engineering strategy to develop stress tolerant rice plants.
