Isolation And Functionalcharacterization Of OsGPDH1 In Rice

Rice is one of the world's most important food crops. Drought is one of the major limiting factors affecting the yield and quality of rice. Water shortage has become an important factor restricting the development of agriculture. And rice is the major water users. Reducing agricultural water use, particularly reducing water use in rice has become the consensus of the world. Therefore, to study the mechanism of drought resistance in rice, to excavate and to identify of candidate genes for drought resistance are significant.Previous studies showed that glycerol-3-phosphate dehydrogenase genes had been involved in the response process of abiotic and biotic stresses. This indicates that the gene has a potential value in environmental stresses. So far, research on the gene in rice has been reported rarely. In order to understand the roles of glycerol-3-phosphate dehydrogenase gene in stress tolerance in rice, a gene encoding a glycerol-3-phosphate dehydrogenase, named as Os GPDH1, was cloned from Nipponbare(Oryza sativa L. ssp.Japonica)in this study. We analyzed the expression levels of Os GPDH1 under various stresses and hormone treatments.We also carried out the germination tests of Os GPDH1-overexpression transgenic plants under high salt environment and counted the survival rate of Os GPDH1-overexpression transgenic plants under drought stress. We preliminarily identified that the gene may be involved in the response to salt stress and drought stress. The main findings are as follows:1. Target protein has two functional domains by the NCBI CDD(conserved domain database), namely NAD(P) binding domain and bottom binding domain. The two domains are highly conserved.2. The expression levels of Os GPDH1 were analyzed by the real-time quantitative PCR.The results showed that the expression of Os GPDH1 occurred in multiple tissues and organs of Nipponbare including the highest expression level in the flag leaf and the lowest expression level in the spikelet.In addition, Os GPDH1 could be induced by PEG6000,hydrogen peroxide, cadmium as well as various plant hormones, such as indoleacetic acid,salicylic acid,jasmonic acid and so on,but insensitive to ABA.3. The full length c DNA of Os GPDH1 was cloned by RT-PCR method and the over-expression vectors were constructed by gateway system. Then we transformed the vector into Nipponbare(Oryza sativa L.ssp. Japonica)and got the transgenic plants. Next,we examined the copy number and expression levels of the target gene in transgenic plants.4. The germination test under exogenous 0.2mol/L NaCl salt stress showed that transgenic rice germination rate was significantly higher than the wild type, indicating that enhancing Os GPDH1 expression could improve rice to the salt-stress resistance.5. The survival rate of the over-expression transgenic plants was significantly superior to the wild-type plants under the 20%PEG6000 stress treatment at seedling stage. It indicatedthat enhancing Os GPDH1 expression can increase the drought-stress resistance at the seedling stage.