Study on Mechanisms of the Oscaf1b Deadenylase in Cold-Relative Gene Expression in Rice(3/3)

Plants are sessile require complex and coordinated gene expression to survive under stress environments. Deadenylation, also called poly(A) tail shortening, disrupts the circularized mRNP structure, which in turn suppresses translation and commits the mRNA to degradation. Thus, deadenylation is an important step in gene regulation that controls mRNA stability and translation efficiency. The CCR4-NOT complex, containing two components CCR4 and CAF1, is a major player in deadenylation. Moreover, the CAF1 have been hypothesized that plays important roles to cope with various environmental stresses in plants. Previously, we identified 4 CAF1 genes, OsCAF1A, OsCAF1B, OsCAF1G and OsCAF1H, from rice that encode recombinant proteins all exhibited 3’ to 5’ exonuclease activity in vitro and tended to remove poly(A) tails. One of them, OsCAF1B, have demonstrated that plays a vital role in sugar-induced αAmy3 mRNA degradation and deadenylation. Our study presents also show that expression of the OsCAF1B gene was cold induced and overexpress the active form of OsCAF1B enhanced cold tolerance phenotype in rice. These results imply that the OsCAF1B play a critical role for deadenylation of cold-responsive gene mRNAs and contribute to rice tolerance to cold. This proposed research focus to study the detail molecular mechanism of the OsCAF1B in cold stress responses in rice. Therefore, the interaction proteins of the OsCAF1B and direct cold-stress related target mRNAs of OsCAF1B will be elucidated. Meanwhile, inducible overexpression of OsCAF1B in transgenic rice plants will be tested for their adaptability under cold stress. Combining the results from these studies, we will have enough knowledge in OsCAF1B-mediated cold tolerance pathway to develop cold stress tolerant rice plants.