Functional Analysis Of Soybean SOS1 Gene In Salt Tolerance By Hairy Rooting Technology

Salt damage is one of the abiotic factors that seriously affects the growth and development of plants.The soil salinization can accumulate large amount of Na+in plants,and thus affects the growth development and yield of plants.However,some plants can grow normally in the saline environment,so the study of salt tolerance gene is of help for understanding the salt tolerance mechanism of plants and can be used to improve the salt tolerance of plants.The GmsSOS1 is a gene cloned from Cultivating and wild soybean by our research group encoding the Na+/H+ antiporter on plasma membrane.Nie et al(2015)cloned the GmsSOS1 from wild soybean and proved that GmsSOSl expression inArabidopsis could significantly increase its salt tolerance by transferred it into Arabidopsis thalianasos1mutant.Zhao et al(2016)demonstrated that the expression of GmsSOS1 in yeast could significantly improve the salt tolerance of yeast by yeast complementary experiments.In this experiment,the GmsSOS1 gene was overexpressed in soybean hair roots(including rooting combination plants and cotyledon roots)by rooting technique,which further verifies the function of GmsSOS1 in salt tolerance.The GmsSOS1 gene was constructed into a plants expression vector pCambia1304,and was transformed into soybean by Agrobacterium rhizogenes.It was verified by PCR that the T-DNA region include GmsSOS1 of the plants expression vector has been integrated into the soybean genome,and GmsSOS1 was overexpressed in the hairy roots under the action of CaMV35S promoter.Two kinds of soybean(Lee68,N23674)with different salt resistance were selected,and theirsoybeanhairy root compositeplantswere established.After 8 days in l00mM and 150mM NaCl treatments,the relative water contend relative conductivity,Na+ and K+contents,antioxidant enzyme activity and chlorophyll content were analyzed.The results indicate that after NaCl treatment,the relative water content and chlorophyll content of true leaves of trans-GmsSOS1 hairy rootcomposite plants were higher than that of trans-vector.The relative electrical conductivity of hair root and leafin trans-GmsSOS1 hairy root compositeplants was significantly lower than that in trans-vector.The Na+content of roots,stems and leaves of trans-GmsSOS1 hairy root composite plants were significantly lower than that in trans-vector.The K+content of hair root processed by 100mM,150mM NaCl and the stem,leaf processed by 150mM NaC1 in trans-GmsSOS1 hairy root composite plants were significantly higher than that in trans-vector.After the same NaCltreatment,the activities of antioxidant enzymes SOD,POD,CAT,APX of trans-GmsSOS1 hairy root compositeplants are significantly higher than that of trans-vector.The soybean cotyledon hairy roots of the overexpression GmsSOS1 were researched.The result shows that after salt treatment,the cotyledon hair roots maximum hair root length and root fresh weight of trans-GmsSOSI were significantly higher than that of trans-vector.The Na+content of cotyledon roots of trans-GmsSOS1 was significantly lower than that of trans-vector,and the K+ contentis significantly higher than that of trans-vector.In summary,by means of decreasing the content of Na+content to improving the relative water content,reducing the relative conductivity,enhancing the activities of antioxidase SOD,POD,APX,CAT,and so on,and increasing the K+content,the overexpression of GmsSOS1 can reduce the salt damage of soybean hair root,so as to improve the salt tolerance.