Gene Cloning And Function Analysis Of OsMED18in Rice

Rice (Oryza sativa L.) is one of the world’s most important food crops and its production is closely related with the rice floral development. The molecular mechanisms of rice floral development has become a current research focus in the research of modern life science. In recent years, the molecular genetic differentiation mechanism of dicot plant flower induction and floral organs formation have been foundmentally definated with the study of developmental mechanisms of dicot plant Arabidopsis. However, the molecular mechanism of monocot plant rice floral development remained still largely unknown.Transcription mediator complex (Mediator complex, MED) is a kind of macromolecular protein complexes and controls the growth and development of plants in transcriptional regulation in eukaryotes. AtMED18was detected in meristem of model plant Arabidopsis and down regulated the FT expression. After that, the med18mutants showed delayed flowering, flower organ defection, and low setting rate., It would be of great significance if the OsMED18gene function was clarified in rice.In the present study, the whole sequence of OsMED18homologous gene was amplified from rice variety Nongken58, and then constructed its over expression and RNA interference transgenic plants to characterize its functions. OsMED18temporal and spatial expression patterns were investigated through semi-quantitative RT-PCR and insitu-hybridization. The results were listed as following:1.OsMED18gene sequence was amplified by PCR, and then its overexpression and RNAi transgenic vectors were constructed.2. The constructed overexpression and RNAi transgenic vectors were transmitted into rice variety Nongken58through Agrobacterium mediate method.3. Total of18lines of positive transgenic seedlings detected by PCR were obtained, of which10lines were OsMED18-KNAi plants, the remaining8were over expression plants.4. Results of SEM and phenotypic analysis showed that the RNAi plants delayed flowering and infertility, whereas over expression plants remained no obvious changed phenotype compared with the wild type.5. Semi-quantitative RT-PCR and in-situ hybridization analysis showed that the expression of OsMED18gene was detected in leaf primordium, shoot apical meristem, receptacle and ovary, while it did not express in leaf primordium and shoot apical meristem in short-day treatment.