Mechanisms Of Rice Unconventional G Protein OsYchF1 In Response To High Salinity And Water Stress

OsYchF1 belongs to rice unconventional G protein and plays a negative regulatory role in rice stress resistance.However,the current research on OsYchF1 mainly uses model plants Arabidopsis thaliana and tobacco as materials,and relatively few studies in rice.High salinity and water stress are the main abiotic stresses in rice growth and development.The response mechanism of rice OsYchF1 in response to high salinity and water stress,and the interaction region between OsYchF1 and its regulatory protein OsGAP1 are studied,it is of great significance to reveal the molecular mechanism of rice stress resistance and to improve rice resistance by genetic engineering.Our main findings are as follows:1.After treatment with 150 mM NaCl and 20% PEG 6000,the growth phenotype of rice Osychf1 mutant was better than that of wild type rice,and the chlorophyll content,fresh weight and dry weight were higher than that of wild type rice.However,the overexpression lines of OsYchF1 were contrary to their mutant growth phenotypes.The overexpression lines almost died after NaCl treatment,and after PEG 6000 treatment,the OsYchF1 overexpression lines were significantly shorter than the wild type.The chlorophyll content,root length,fresh weight and dry weight of the two treatments were almost significantly or very significantly lower than those of the wild type rice.The results also showed that rice Osychf1 mutants were more resistant to high salt and water stress than wild type rice,while rice OsYchF1 overexpressing lines were more sensitive to stress.2.After treatment with 150 mM NaCl and 15% PEG 6000,the SOD(superoxide dismutase)enzyme activity of rice Osychf1 mutant was significantly or very significantly higher than that of wild type rice,CAT(catalase)and POD(peroxidase)enzyme activity was also higher than those of wild type,and the content of MDA(malondialdehyde)was lower than that of wild type rice,and there were significant differences;on the contray,the SOD activity of rice OsYchF1 overexpressing lines was significantly or very significantly lower than that of wild type.The results showed that under high salt and water stress,the antioxidant stress ability of Osychf1 mutant was higher than that of wild type,while that of OsYchF1 overexpressing line was lower than that of wild type.3.In pot experiment,compared with wild type rice,the tiller number of rice Osychf1 mutant was significantly higher than that of wild type,and the panicle number,grain number per panicle,seed setting rate and yield of OsYchF1 overexpressing line were lower than that of wild type rice,and there were significant differences.4.Previous studies showed that rice OsYchF1 protein could interact with OsGAP1,and ultimately inactivate OsYchF1 protein.OsGAP1 may participate in rice stress resistance as a positive regulatory factor.Our preliminary results showed that under 150 mM NaCl and 15% PEG 6000 treatments,rice Osgap1 mutant was more tolerant to stress than wild type rice,and its root length,fresh weight and dry weight were significantly or very significantly lower than those of wild type rice.These results suggest that OsGAP1 mutation may not regulate the activity of OsYchF1,resulting in Osgap1 mutant more tolerant to high salinity and water stress than wild type,and further suggest that OsGAP1 may participate in drought and salt tolerance response as a positive regulator.5.In order to study the interaction region between OsYchF1 protein and OsGAP1,we predicted the possible interaction model of OsYchF1 and OsGAP1 in space,then detected them by pull-down technique.In the interaction region,OsYchF1 interacts with OsGAP1 through its G domain.These results suggest that OsYchF1 plays a negative regulatory role in response to high salinity and water stress in rice.Osychf1 mutant of rice is more tolerant to high salinity and water stress than wild type rice.Overexpression lines of OsYchF1 in potted rice are lower in yield than wild type rice.In addition,OsGAP1 may be a positive regulator of drought and salt tolerance in rice.OsYchF1 protein interacts with OsGAP1 through its G domain.Therefore,rice OsYchF1 and its interaction protein OsGAP1 may be the key factors regulating drought and salt tolerance in rice.