Functions Of Heat Shock Transcription Factor OsHSF18 In Regulating Rice Stress Resistance

Rice (Oryza sativa L) is one of the most important crops in the world. High temperature can lead to large-scale decrease of rice yield. Under high temperature, heat shock response is activated in plant. Upon this response, the heat hock proteins are induced and the plant tolerance to stresses is enhanced. The heat hock proteins are mainly regulated by heat shock transcription factors. The aim of this research is to clarify the biological functions of OsHsfl8 through overexpressing and RNAi silencing this gene, which aim to provide theoretical foundation for rice stress resistance breeding.The overexpression and RNAi vector of OsHsf18 were constructed and introduced into rice variety Nipponbare by Agrobaterium mediated transformation. After identification, we got 17 overexpressing lines and 5 RNAi lines. Then, the resistance of these two transgenic plants against bacterial blight was analyzed. The results showed that the OsHsf18 overexpression plants were more resistant against bacterial blight comparing with non-transgenic control plants, while the RNAi plants were more susceptible. Moreover, the transcriptional level of resistance related marker genes were induced in OsHsfl8 overexpression plants. In total, OsHSF18 can regulate plant disease resistance. In addition, the transcription level of OsHsfl8 under high temperature, high concentrate salt and drought were detected, and found that OsHsfl8 was induced by these 3 stresses. Therefore, OsHSF18 plays an important role in regulating rice stress.The agronomic traits of OsHsf18 transgenic plants showed that the overexpression plants are shorter than non-transgenic plant, and all of the tiller number, ripening rate and thousand seed weight are also decreased. However, the OsHsf18-RNAi transgenic plants have no significant difference with control in plant hight and tiller number but ripening rate and thousand seed weight of RNAi plant are decreased. In conclusion, both overexpression and knocking down of OsHsf18 affect rice growth and development.