Cloning And Functional Analysis Of CdSAP1 In Bermudagrass

Bermudagrass(Cynodon dactylon)is widely distributed in tropical and subtropical regions,it is a good warm-season turgrass of heat resistant,drought resistance,trampling resistance and excellent characteristics.There are a number of strong salt tolerance genotypes in Bermudagrass.Bermudagrass has great application prospect in saline and salinization soil.However,the study of Bermudagrass salt tolerance mainly focused on salt-tolerant germplasm resources evaluation and physiological mechanism,the molecular mechanism of salt tolerance is still missing.SAP(Stress associated protein)can encode a protein which contains A20/AN1 zinc finger protein domain.SAP can involve in the stress response process of plants,but the molecular mechanism of regulation is still unclear.We cloned a stress associated protein CdSAP1 from the bermudagrass,we analyzed the sequence encoding the protein,expression characteristics and the physiological and molecular mechanisms of salt tolerance.The main results were as follows:(1)We cloned CdSAP1 from bermudagrass.The CdSAP1 full-length cDNA is 811bp,the open reading frame(ORF)is 516 bp.The gene encoding a protein with 171 amino acids.A phylogenetic tree revealed that the gene is a putative ortholog of OsSAP8,OsSAP4 in rice and AtSAP2 in Arabidopsis thaliana.qRT-PCR data demonstrated that NaCl,ABA,PEG significantly induced the CdSAP1 expression in leaves,at 12h the expression was the highest.(2)We transformed CdSAP1 heterologous gene into Arabidopsis.CdSAP1 can significantly improved salt tolerance in Arabidopsis according to the forensic analysis.Further studies showed that under salt stress,transgenic plants can significant increase seed germination rate and reduce the leaf scorch rate and the electrolyte leakage.Transgenic plants can maintain higher chlorophyll content,higher photochemical efficiency,higher photo synthetic rate and lower intercellular CO2.Transgenic plants significantly reduces the accumulation of Na+ under salt stress,in order to maintain lower Na+/K+.Transgenic plants can promote the accumulation of proline and soluble sugar and reduce the accumulation of H2O2 and O2-.(3)The expression of the salt tolerance related genes function analysis showed that under salinity conditions CdSAP1 overexpression significantly increased expression level of AtNHX1,AtSOS1,AtP5CS,AtAPX,AtSOD and AtPOD genes in leaves,but the expression of AtAKTI and AtBADH genes were not affected remarkably.In roots,CdSAP1 overexpression significantly increased expression level of AtNHX1,AtBADH,AtAPX,AtSOD,AtPOD genes,but the genes expression of AtSOS1,AtAKTI and AtP5CS were not affected remarkably.