Function Analysis Of Stress Tolerance Gene OsSTAP1 In Rice

Ethylene responsive factor(ERF) genes encode plant-specific transcription factor(TF), which is widely involved in plant growth, development and metabolism as well as response to different environmental stresses. Stress response in plants is a complicated process regulated by many different signaling pathways. Identifying functional candidate genes for stress resistance in rice will provide valuable information to dissect the signal pathway, physiological and molecular regulation mechanisms of rice responding to environmental stress.In previous study, forty-two AP2/EREBP TF genes were identified as functional candidate genes involved in abiotic stress responses by using microarray analysis, of them, two genes including OsSTAP1 were found to be responding to all stresses including salt, cold and drought. In this study, the function of OsSTAP1 was further characterized. The complete coding sequence(CDS) with a length of 1005 bp of OsSTAP1 was amplified from Nipponbare. Bioinformatics analysis indicated that the OsSTAP1 protein has a conserved AP2 DNA binding domain with specific GCC-box binding domain and the AP2 domain of OsSTAP1 protein has two conserved amino acid residue-A14 and D19. All these results indicated that OsSTAP1 belongs to ERF member of AP2/EREBP TF. Further cluster analysis showed that OsSTAP1 belongs to subgroupⅣ with a homologous protein AT1g53910 in Arabidopsis. The proximal promoter region of OsSTAP1 contains many plant hormones response elements and stress response elements. GFP-OsSTAP1 subcellular localization implied that OsSTAP1 protein was localized in nucleolus. Gene expression profiling showed that OsSTAP1 gene was induced by various plant hormones and different abiotic stresses.The function of OsSTAP1 gene was further characterized by transformation of Nipponbare mediated by Agrobacterium. Both of PCR and Southern blot results confirmed that the target gene had been integrated into the genome of transgenic rice lines; The expression of OsSTAP1 in all transgenic plants were evidently over-expressed, and the transgenic plants with over-expression of OsSTAP1 exhibited significant salt stress tolerance with high activities of oxidoreductase. In conclusion, the OsSTAP1 gene can be induced by various plant hormones and abiotic stresses, and functioning in cell nucleus by binding to GCC-box of downstream genes. The high expression of OsSTAP1 gene in transgenic plants could result in increasing the oxidoreductase activities, and scavenging oxygen free radicals caused by salt stress, than alleviating oxidation stress, and enhancing the salt tolerant capacity.