Cloning And Functional Analysis Of OsHSP90 Gene In Rice

Rice is an important crop and its yield and quality is very significantly affected by stresses. Therefore, it is very important to research the rice response to adverse stresses. In recent years, with the development of molecular biological theory and technology, the study on stress-related genes has made great progress. Some stress-related genes have been found successively and transformed into rice. And the transgenic plants possess higher tolerance to stresses. These research will help us to understand the molecular mechanism of rice resistance to abiotic stress and will provide important guidance for screening and breeding rice varieties possessing resistance to abiotic stress.Heat Shock Protein HSP90 is a widespread and important stress-related protein in organisms. HSP90 widely exists in all kinds of cells under nomal conditions, and the expression of HSP90 increased under stress conditions. As an important chaperone, HSP90 can help proteins to fold correctly, keep the integrity of their conformations and maintain the biological functions of proteins under normal and stress conditions. At the same time, it can interact with a subset of substrate proteins and involve in the regulation of cell metabolism and signal transduction. Furthermore, a lot of studies show that over-expression of the gene can improve the tolerance to stress in organisms.A heat shock protein HSP90 was screened by fluorescent differential display technology in rice in our lab several years ago. It was located on chromosome 9. This paper discussed primarily some biological functions of the protein in rice. The research results can provide helpful information and help us to further understand the regulatory role of OsHSP90 gene in response to stresses. The main findings are as follows:1. Analyzing the sequence of the OsHSP90 gene, the encoding frame of the gene is 2100 bp and it encodes a protein containing 699 amino acid residues. Its isoelectric point is about 4.97 and its relative molecular weight is predicted to be 80.19kDa. Analysis of its protein domains showed that there are two domains in OsHSP90 sequence (ATPase at 30 to 179, Pfam:HSP90 at 185 to 699).2. We analyzed the expression levels of OsHSP90 gene in rice Nipponbare under some stress conditions such as high temperature, drought and salt treatment using real-time qRT-PCR technology.3. We constructed prokaryotic expression vector of the gene and induced its expression in vitro. Meanwhile we determined the growth status of E.coli expressing OsHSP90 under stress conditions. The results showed that expression of the gene could enhance the tolerance to heat and drought in E.coli, but have no direct relationship with improvement of tolerance to salt in E.coli.4. We constructed transgenic expression vector of the gene and obtained the correspo-nding homozygous transgenic plants. Then we determined the tolerance to high temperature, salt and drought stress. We found that overexpression of OsHSP90 gene could enhance tolerance to high temperature stress, have a certain relationship with improvement of tolerance to osmotic stress, but seemed to have no direct effect on tolerance to salt in rice.5. We constructed GFP vector of the gene for subcellular localization analysis and the experiment is still ongoing.