Analysis Of Drought Resistance And Flowering Function Regulated By Soybean GmANKTM21 Gene

Soybean(Glycine max(Linn.)Merr.)is a widely grown food and cash crop,and soybean yield is highly susceptible to environmental stresses such as drought.Therefore,to explore the function of drought tolerance genes in soybeans and to discover the mechanism of drought resistance have great significance for soybean breeding and stable yield.In our previous study,it is found that WRKY20 gene can increase soybean drought tolerance and regulate soybean flowering time.Upregulated expression of the Gm ANKTM21 gene was found in the transcriptome sequencing of WRKY20 overexpressing soybean.The Gm ANKTM21 protein contains ANK domain and transmembrane domain,and belongs to the ANKTM(Ankyrin repeats transmembrane)family.In order to clarify whether Gm ANKTM21 gene has stress resistance function,this study carried out genome-wide analysis of soybean ANKTM family members.Expression of Gm ANKTM21 gene in different tissues and under drought stress were analyzed;Analysis of the subcellular localization of Gm ANKTM21 was performed.The coding sequence of Gm ANKTM21 was cloned and the plant expression vector was constructed.Then Gm ANKTM21 gene was transferred into the soybean variety Dongnong 50 by using Agrobacterium transformation method.Transgenic plants overexpressing Gm ANKTM21 was obtained,and the plant development and drought tolerance were detected.The main findings obtained are as follows:(1)The protein encoded by Gm ANKTM21 gene contains 591 amino acids with a molecular weight of 66421.51 Da and an isoelectric point of 8.27.The protein encoded by the Gm ANKTM21 gene contains five ANK motifs and four transmembrane domains.The promoter region of the Gm ANKTM21 gene contains four hormone-related elements,six photoresponsive elements,and two stress response-related elements.(2)The Gm ANKTM21 gene is specifically expressed in leaves and roots,and expressed in some tissues such as flowers,beans,stems,and pods at low level.Moreover,the expression of Gm ANKTM21 gene was affected by salt,alkali and drought stress,but the response to low temperature stress was not obvious.The Gm ANKTM21 gene was found to be localized in the nucleus and cell membrane.(3)The Gm ANKTM21 gene was cloned and the overexpressing plant expression vector was constructed.The soybean plants were transformed by the Agrobacterium transformation method and obtain 3 copies of the gene overexpressing plants.(4)Overexpression of Gm ANKTM21 gene resulted in early flowering,and the expression levels of Gm FT2 a,Gm FT5 a and their downstream floral meristem genes Gm AP1 a and Gm AP1 b were significantly increased in transgenic plants.At the same time,overexpression of Gm ANKTM21 gene enhanced drought tolerance.The contents of antioxidant enzymes(SOD,POD,CAT)and osmotic regulators(soluble sugar,proline)increased and meanwhile,the degree of membrane lipid damage was reduced significantly in transgenic plants,indicating that protective enzyme system may play an important role in improving drought resistance in transgenic plants.