Breeding Of Transgenic Rice With Drought Resistant Using OsSINAT5Gene And Its Mechanism Of Drought Resistance

Drought is an important factor influencing rice production. Transgenic breeding strategy is an effective way for breeding rice cultivars with drought resistance. The rice OsSINAT5gene encodes a RING-finger type E3ubiquitin ligase. Overexpression of this gene reduces resistance to drought in rice, but RNA interference of this gene increases resistance to drought in rice. The study of OsSINAT5is usful for cultivating rice cultivars with drought resistance.We used Agrobacterium-mediated transformation method to improt OsSINAT5-RNAi vector into high yield and high quality rice cultivar R996. Through screening with hygromycin solution and PCR analysis of hygromycin resistance gene for T1generation transgenic plants, we identified several positive transformants. RT-PCR analysis and severe drought treatment for the OsSINAT5-RNAi T2generation showed that drought tolerance was increased along with reduction of OsSINAT5transcription level.Recent research shows that drought resistance is related to ABA signal pathway. We analyzed sensitivity of OsSINAT5-RNAi transgenic plants to ABA which is a drought resistance regulator, however, the results showed that there were no difference between OsSINAT5-RNAi plants and control in plant height, root length and germination rate before and after the ABA treatment. And the transcription level of OsBZIP23which is a ABA pathway drought regulator in the transgenic plants as similar as the control. Therefore, the drought resistance regulated by OsSINAT5is independent on the ABA pathwasy. In addition, transcriptional level of OsSIK1and OsSKIPα which are the antioxidant pathway’s drought regulators were increased in OsSINAT5-RNAi plants after drought treatment. These results suggested that OsSINAT5may negatively regulate drought tolerance through antioxidant pathway.