Molecular Cloning And Functional Characterization Of UV-B Photoreceptor Gene MdUVR8in Apple

UVR8is a kind of photoreceptors which specifically response to ultraviolet-B (UV-B) signal, and regulate plant growth and development. UVR8has been proved to be widespread existed in higher plants, algae and moss, and its function has been identified in the model plant Arabidopsis thaliana. Light plays an important role in the photomorphogenesis of fruit trees, where the blue photoreceptor cryptochrome function has been identified in apples, but no studies on the fruit of UV-B photoreceptors. In this study, it was cloned from apple that a UV-B photoreceptor gene MdUVR8, and its structure, expression and its specific functions were analyzed and identified in plants. The main research works and results are as follows:l.The full length of cDNAs of MdUVR8were obtained by using RT-PCR and RACE amplification. MdUVR8and AtUVR8conservative contain seven RCC1domains indicated that they were had the similar function in growth of the plant engineering. The full length cDNA of MdUVR8is1957bp in length. Its ORF is1539bp and encodes a polypeptide containing512amino acid residues. The predicted protein is48.8kDa in molecular weight.2. RT-PCR analysis showed that MdUVR8constitutively expressed in all tissues tested. In addition, the expression of MdUVR8were in response to UV-B light. The result indicated that the expression of the gene was noticeably induced in response to UV-B. These results suggested that MdUVR8are involved in light responses in apple.3. Functional complementation test showed that the ectopic expression of MdUVR8recovered the developmental defects in photomorphogenesis in Arabidopsis mutant uvr8seedlings to a certain degree, respectively. Meanwhile, overexpression of the gene in WT enhanced photomorphogenesis phenotypes, respectively. These results indicated that MdUVR8regulate plant photomorphogenesis in response to light signal.4. Yeast-two-hybrid and Co-immunoprecipitation (CO-IP) assays indicated that MdUVR8interact with Arabidopsis MdCOP1protein, further confirming that both proteins are components in light signaling pathway in apple.