The Function Of NHX1 And SOS1 Genes And Their Promoters Of Three Poplars

Populus euphratica, P. russkii and P. bollena were used as materials in this research. The expression level of four selected genes under salt stress were studied. We cloned PeNHX1 and PeSOS1, and constructed the yeast expression vectors to analyze their functions. In order to further reveal the functions of NHX1 and SOS1 in Na+ transport regulation of poplars, the promoters of PeNHX1, PeSOS1, PrSOS1, PbSOS1 were cloned too. It will have important implications for the distribution of Na+ and salt resistance of poplar, and provide guidance and theoretical support for the salt tolerance breeding of crops in future. The main conclutions are as follows:The differences of expression of related genes under salt stress were analysed by RT-PCR. PeNHX1 expression decreased and the expression level of PeSOS1 gene increased nearly 3 times to the original. The expression variations of salt stress related genes of P. russkii is not obvious. HKT1-1 and HKT1-2 show a trend that first increased and then decreased. The increase of expression of HKT1-1 and HKT1-2 in a short time can provide a signal for plants to adapt to the long-term stress, and impel the plant to synthesize other osmotic regulators.PeNHX1 and PeSOS1 were cloned. By analysis the transmembrane domains we found that PeNHX1 had 10 transmembrane domains and PeSOS1 had 12 transmembrane domains. In order to verify the function of NHX1 and SOS1 genes, two genes were digested and ligated to the yeast expression vector pYES2, and transformed into salt sensitive phenotype yeast G19 to express PeNHX1 and PeSOS1 genes in heterology. But PeNHX1 and PeSOS1 cann’t completely replace the function of the yeast ScNHX1 protein.Four promoters— pPeNHX1, pPeSOS1, pPrSOS1 and pPbSOS1 were cloned. To analyze the biological information, the results showed that they are obvious differences in the sequences. The numbers and locations of cis-acting elements have certain differences. But they all have GT1-motif which is related to salt stress. The promoter :: GUS gene fused expression vectors—PeNHX1Pro:: GUS, PeSOS1Pro:: GUS, PrSOS1Pro:: GUS and PbSOS1Pro:: GUS were constructed and transferred into P. russkii. The P. russkii leaves were used as explants for inducing callus, the conditions of subculture and differentiation were optimized, regenerated plants were obtained.