Functional Analysis Of Grape VvABF2 Gene In Arabidopsis Osmotic Stress

Grape is one of the most cultivated fruit trees in the world,with an annual output of 700 million tons and a harvest area of more than 700 million hectares.Grape is mainly used for fresh grapes,wine making,drying raisins,etc.However,in the process of fruit tree cultivation,it often encounters stress such as drought,high temperature,cold damage,disease and soil salinization,which seriously affects the normal growth and development of the grapevine.Studies have shown that the bZIP transcription factor can effectively regulate the expression of stress-related functional genes in response to abiotic stresses in plants so as to improve plant stress resistance.In this study,a bZIP gene,VvABF2,was cloned from sequenced grape genotype Pinot Noir(PN40024)and transformed into Arabidopsis thaliana by floral dip method,and the function was studied.The main findings are as follows:1.Through the analysis of the grape genome database and the phylogenetic tree of the bZIP gene family,with that of Arabidopsis,the VvABF2 gene was cloned from Pinot Noir(PN40024).This gene is highly homologous to Arabidopsis AtABF2 gene and is therefore named VvABF2.The open reading frame of VvABF2 was 1344bp,encoding 447 amino acids.The predicted molecular weight of VvABF2 was 47.88 kDa and the isoelectric point was 9.41.In this paper,functional verification of VvABF2 gene under salt stress conditions was carried out.2.Transgenic Arabidopsis lines with octopic expression of VvABF2 were used as experimental materials to investigate the resistance of transgenic Arabidopsis thaliana for abiotic stress.The results showed that the phenotypes of transgenic Arabidopsis after ABA treatment were significantly different from those of wild type.After 10 days of salt treatment,the wild-type leaves were generally stressed while the transgenic Arabidopsis plants were relatively green.After 20 days,Wild-type Arabidopsis all died,while the transgenic Arabidopsis plants survived,showing significantly higher than wild-type Arabidopsis thaliana.Simulated drought and spraying ABA treatment for one week,transgenic Arabidopsis thaliana relative to the wild type plants,grew relatively better;and simulated drought without ABA treatment for one week,the transgenic and wild-type Arabidopsis phenotypes had not shown much difference.The growth of transgenic plants was poor,indicating transgenic Arabidopsis drought resistance is dependent on exogenous ABA stimulation.Therefore,it was demonstrated that VvABF2 transcription factor plays an important role in response to abiotic stress in plants,the response to drought stress is ABA-dependent.3.In order to further explore the response mechanism of VvABF2 transcription factor gene in drought stress,the physiological indexes of transgenic Arabidopsis thaliana and wild type Arabidopsis were measured after simulated drought and high salinity treatments.In addition,the leaves on the stoma size and density were measured,and the results showed that the pore size of the transgenic seedlings was larger than that of the wild type under drought stress.Compared with wild-type Arabidopsis,transgenic Arabidopsis had lower MDA content after high-salt treatment and higher activities of antioxidant enzyme such as SOD/POD/CAT.In addition,Transgenic Arabidopsis also had higher proline content.Similarly,the transgenic Arabidopsis had higher antioxidant enzyme activity and proline content and lower MDA content after simulated drought stress,which indicated that transgenic Arabidopsis plants have enhanced stress resistance by enhancing ROS scavenging capacity and inhibiting the accumulation of reactive oxygen species(ROS)to regulate gene expression associated with stress tolerance.