Study On Salt Tolerance Of Suaeda Dehydrin Gene (SsDHN)

In this study,the wild-type tobacco NC89 and the tobacco transferred to the Suaeda dehydrin gene(DHN-1?DHN-2?DHN-3?DHN-4)were used as experimental materials.The Western-blot technique and real-time fluorescent quantitative PCR technique were used to detect the transgenic materials obtained at the molecular level.Under stress conditions,the expression of exogenous genes in transgenic tobacco plants and physiological and biochemical levels of plants were studied and explored to reveal the stress resistance mechanism of dehydrin genes in plants.The results of the study are as follows:1.The positive control of Phalaenopsis of Panjin Red Beach and the negative control of wild-type tobacco were used to detect the expression level of PCR-positive DHN-1,DHN-2,DHN-3 and DHN-4 four transgenic strains by Western blot.All the four transgenic tobaccos were positive,indicating that the exogenous dehydrin gene successfully expressed dehydrin protein in tobacco.2.The qRT-PCR technique was used to determine the expression of dehydrin genes in roots and leaves of transgenic tobacco under low temperature and salt stress conditions.The results showed that the SsDHN gene was up-regulated in the four transgenic plants under low temperature stress,but the expression of dehydrin gene in leaves of DHN-1 was the highest at12 h,and the dehydrin gene expression in leaves of DHN-2,DHN-3 and DHN-4 was 24 h at the treatment time.At the highest point,the expression of dehydrin gene in DHN-1 root was the highest at 24 h,and the dehydrin gene expression in DHN-2,DHN-3 and DHN-4 roots was highest at 12 h treatment time.The results of salt stress indicated that SsDHN was expressed in four transgenic plants.All genes were up-regulated.The expression of dehydrin gene in leaves of DHN-1 was highest at NaCl concentration of 100 mM.The expression of dehydrin gene in leaves of DHN-2 was highest at NaCl concentration of 200 mM,and the expression of dehydrin gene in leaves of DHN-3 and DHN-4 was at Na Cl concentration.300m M peaked,and the dehydrin gene expression levels in DHN-1,DHN-2,DHN-3 and DHN-4roots were highest at Na Cl concentration of 300 mM.3.Through the statistics of the germination rate and root length of wild-type tobacco and dehydrin-transgenic tobacco on MS medium with different salt concentrations,the germination rate of transgenic tobacco was higher than that of wild-type tobacco at the same salt concentration,and was found by comparing the root lengths.The wild-type tobacco root cultured on the MS-free MS medium grew longer than the transgenic tobacco,but compared with the same salt concentration,the root length of the transgenic tobacco was longer than that of the wild type,indicating that the SsDHN gene can increase the salt tolerance of tobacco;At 200 m M NaCl concentration,leaf shrinkage occurred in both wild-type and transgenic tobacco plants.The seedlings were transferred to normal medium.After 6 days,transgenic tobacco returned to normal and wild-type tobacco recovered after 10 days.4.The contents of K~+and Na~+in leaves and roots of wild-type and transgenic tobaccos under different salt concentrations were measured.It was found that under different NaCl concentrations,the content of K~+in transgenic tobacco increased,and the transgenic tobacco DHN3 was under salt stress.The content of cadmium was higher than that of wild type.When NaCl concentration was 400 mM,the K~+content in transgenic tobacco roots tended to be 0;the content of Na~+in transgenic tobacco under salt stress conditions was higher than that under normal conditions,but under the same concentration of Na Cl,the transgene was transformed.The content of Na~+in tobacco is lower than that of wild type,indicating that the sSDHN gene can maintain the balance of intracellular K~+and Na~+and protect the plant from ion toxicity.