Preliminary Function Analysis Of The Stress-related Gene OXHS2 In Rice

Due to less rainfall and climate change,drought stress is becoming more severe to many crops,especially rice.Therefore,exploring drought tolerance genes and investigating their mechanism will have an important practical significance in breeding drought tolerance varieties and improving the drought tolerance.In the previous study,we identified a novel XHS family in rice,which contains conserved Zf-XS,XH,XS and Coiled-Coil domain and plays important roles in panicle development and stress tolerance.OXHS2 is an atypical XHS protein which lacks the Zf-XS domain,and induced obviously by drought stress.In this study,we plan to research the tissue expression profile of OXHS2 by promoter analysis,verify whether Zf-XS could play function as nuclear localization signal by subcellular localization and identify the function of OXHS2 on drought resistance through mannitol-mediated osmotic stress and drought stress in the rice seedling stage.The main results are as follows:1.The rice gene OXHS2 promoter was isolated and constructed into DX2181 vector,and 10 positive transgenic plants were acquired by Agrobacterium-mediated transformation.Fluorescence observations showed that OXHS2 was expressed strongly in pistil and stomata,and was barely expressed in other tissues.The results showed that OXHS2 may play important roles in the development and related functions of pistil and stomata in rice.2.The OXHS2 overexpression and RNAi transgenic lines were identified through qPCR,and then all strains were tested by osmotic stress(100mM mannitol)and drought stress at seedling stage.The results showed that the length of shoot and root in both OXHS2 overexpression and RNAi transgenic lines were significantly shorter than ZH11 after 10 days with 100 mM mannitol treatment,and the survival rate of all transgenic lines was also significantly lower compared to ZH11 after drought stress.The results revealed that OXHS2 may be a key factor in the path of drought resistance signal,which may play a positive regulatory role in the early stage of drought and contribute to the early stage drought resistance of rice.However,with the persistence of drought stress,the accumulation of OXHS2 may affect the growth of rice and cause harm,thus affecting the drought resistance of rice.3.The transient expression vector OXHS2-GFP-HBT and ZXHS2-GFP-HBT were constructed and transformed into protoplasts,respectively.Fluorescence observation showed that protein OXHS2 was located in the cytoplasm,while The protein ZXHS2 that was added to the Zf structure was located in the nucleus.The results suggested that nuclear localization signal presents in Zf-XS domain.