Function Analysis Of The OsHSP90 Family In Rice

As the extreme weather become more frequent in the recent years, the adverse effect of heat, cold, drought and salinization on growth, development, yield of crops become more and more prominent. Study on the mechanism of crop resistance and breeding more resistant crops become the upmost problem to be solved.The HSP90 is an abundant chaperone protein that is conserved in all eukaryotes. The main function of HSP90 is to assist other proteins to fold properly, while play a significant role in the stress response network. In this study, we made use the tools of Bioinformatics to uncovered and analyzed nine OsHSP90 (OsHSP90-1-OsHSP90-9) family members in rice Nipponbare, in which three distinct motifs were identified. All the HSP90 proteins were classified into three major groups (?, ?, ?) by phylogenetic analysis. The expression of OsHSP90 family in 10 tissues was examined by real time PCR. OsHSP90-4, OsHSP90-6 and OsHSP90-7 had high expression, while OsHSP90-5 and OsHSP90-8 had very low expression across almost all 10 samples. The gene that encodes OsHSP90-1 was preferentially expressed in embryo at 14 days after flowering. It has been reported that some heat shock proteins were up-regulated in response to heat or other stresses. But in our study, the expression pattern of OsHSP90 genes is heterogeneous under a range of stress conditions. The expression of OsHSP90-2, OsHSP90-4 was up-regulated under drought, salt, cold and heat conditions, while the expression of OsHSP90-3, OsHSP90-5 was down-regulated under salt and drought conditions. OsHSP90-7 and OsHSP90-9 were down-regulated only under drought conditions. OsHSP90-6 did not change its expression across all conditions compared to control. Overexpression of OsHSP90-2 and OsHSP90-4 in E. coli respectively, could enhance cell viability and significantly improved resistance to heat, high salinity, and drought stress conditions. Overexpression of OsHSP90-2 and OsHSP90-4 in rice Nipponbare, only OsHSP90-4 could result in significantly increased resistance to heat and sensitivity to ABA. The results presented here may provide new insights into the function of OsHSP90 family in rice.