Functional Study Of HgS5 Gene Of Salt Stress Response In Halogeton Glomeratus

Halogeton glomeratus belongs to the annual Halogeton genus plant of Chenopodiaceae family,which has strong drought and salt tolerance.It is an important wild resource for obtaining genes of drought resistance and salt tolerance.In this study,the function of salt stress response gene HgS5 in Halogeton glomeratus was studied.The main conclusions are as follows:1.The gene HgS5 was cloned from Halogeton glomeratus and bioinformatics analysis was carried out.Results showed that the full length of HgS5 is 1738 bp,and its cDNA coding sequence contains 1110 bp and encods 370 amino acids.There is no transmembrane region in the protein encoded by this gene,which belongs to nontransmembrane protein.The coding protein of HgS5 is hydrophilic protein by online software analysis combined with average hydrophobicity and fat coefficient analysis.According to the secondary structure prediction,the ratio of random coil is the most,reached 64.05%,and the ratio of ?-turn is only 1.62%.There are sites of Serine and Tyrosine in the coding protein.Subcellular localization showed that the protein of HgS5 is mainly located in the nucleus.2.The overexpression vector p Cambia2301-HgS5 was successfully constructed according to the full length of cDNA of HgS5 gene and the overexpression vector p Cambia2301,and the genetic transformation was carried out by infecting Arabidopsis thaliana with Aturobacterium-mediated soaking method.The T2 positive transgenic strains were obtained by Kan resistance screening and PCR identification.3.T2 transgenic Arabidopsis thaliana of HgS5 had significant drought resistance under drought stress,without salt tolerance under Na Cl stress.There was no significant difference for seeds germination between transgenic and wild-type Arabidopsis thaliana under low concentration PEG stress treatment(5%PEG and10%PEG).Under the higher PEG concentration stress treatment(15%PEG),the germination potential of transgenic Arabidopsis thaliana seeds was significantly higher(P<0.05)than that of wild-type Arabidopsis thaliana seeds,and up to 98.89%,but there was no difference in germination rate between transgenic and wild-type Arabidopsis thaliana.Under high concentration stress treatment(20%PEG),the germination rate of transgenic Arabidopsis thaliana seeds was 22.13% higher than that of wild-type Arabidopsis thaliana seeds,and reached a significant level(P<0.05).The activity of Superoxide dismutase(SOD),Peroxidase(POD)and Catalase(CAT)increased firstly and then decreased with the extension of drought stress.Under mild drought stress(0d-6d,the soil water content was from 50% to 30%),the content of oxidase in plants began to accumulate and the content of three kinds of oxidase in transgenic Arabidopsis thaliana was lower than that in wild-type Arabidopsis thaliana.Under severe drought stress(6d-12 d,the soil water content was from 30% to 5%),the content of oxidase in plants decreased in varying degrees,and then the content of three kinds of oxidase in transgenic Arabidopsis thaliana was higher than that in wild-type Arabidopsis thaliana.From the above experimental data,it can be concluded that HgS5 gene has the function of improving the drought resistance of transgenic Arabidopsis thaliana.4.Real time fluorescence quantitative PCR analysis showed that the expression level of HgS5 gene in roots was significantly higher than that in leaves for transgenic Arabidopsis thaliana under drought stress(P<0.05).5.The subcellular localization vector PBI121-GFP-HgS5 of HgS5 was transformed into tobacco by Agrobacterium tumefaciens.The distribution of green fluorescence was observed.The results showed that HgS5 was mainly expressed on cell membrane.