Functional Study On The Role Of MiR166 And Its Target Gene HD-Zip In Rice Cadmium Stress Response

Rice is the world’s major food crops. In recent years, heavy metal pollution has become one of the major issues causing adverse effects on farmland ecosystems and rice production safety. mi RNAs, a new class of small molecular RNAs that regulate gene expression, play an important role in regulating plant responses to various stresses like heavy metals stress. Among these mi RNAs, the mi R166 participates in plant responce to drought, chilling injury and heavy metal stress through regulating the expression of transcription factor, the HD-Zip.The experiment takes in cadmium(Cd) stresses-related mi R166 that is isolated from the early laboratory research and target genes HD-Zip as the research objects; The homozygous offspring of 35S: MIR166 m and 35S: HD-Zip over-expression transgenic rice T2 generation was identified. At the same time, the analysis of mi R166 timing sequence expression pattern was complished. Then, in the Cd stress experiment of over-expression transgenic rice, the expression quantity of mi R166 m and HD-Zip in control group and Cd treatment group, MDA, H2O2, Cd content and Cd sub-cellular distribution were analyzed; the comparison of the differences of multiple indicators between the Cd treatment group and control group shows that over-expression mi R166 m inhibits Cd root absorption and transport from the root to over-ground part and improves the tolerance of the rice on Cd; HD-Zip over-expression enhances the absorption of rice on Cd and the transport to the over-ground part. The results indicates the negative regulation of mi R166 on the target genes and its specific roles in Cd stress response of rice, and lays a foundation for studying the Cd stress response regulatory mechanism of rice mi R166 and the target genes.