| China is the origin country and the largest producer of peach in the world.In recent years,abiotic stress has become an important factor restricting the development of the peach industry.As one of the most abundant and conserved families in eukaryotes,TST sugar transporters are mainly involved in various physiological processes such as plant biotic and abiotic stress responses,growth and development.However,the biological functions of TST sugar transporters in peach have not yet been established.We cloned the PpTST2-T gene and performed bioinformatics analysis,and then detected the expression of PpTST2-T under adverse conditions,and found that drought,salt,high temperature and ABA can induce the expression of PpTST2.Then,using wild-type tomato and 35S:PpTST2-T transgenic plants as materials,the plant phenotype,growth state and physiological indicators under drought stress were determined and analyzed.In addition,the yeast single-hybrid assay and dual-luciferase assay demonstrated that Pp ABRE1 can activate the expression of PpTST2.The main results are as follows:（1）PpTST2-T is in the same subfamily with At TST1 and At TST2 of Arabidopsis TST family.The amino acid sequence similarity shows that At TST2 has the highest amino acid similarity with PpTST2-T.The total length of the c DNA of PpTST2 is 2220 bp,encoding 740 amino acids,the predicted molecular weight of the encoded protein is 78.91 k Da,and the isoelectric point is 4.8.Analysis of promoter elements showed that it has various functional elements involved in drought stress,hormone response,light response and sugar response.（2）The PpTST2-T gene was cloned and its expression specificity was analyzed.It was found that PpTST2 was expressed in all tissues,and the expression level was higher in flowers and pulp,followed by peel and leaves.The expression of PpTST2 gene can be induced by drought,salt,high temperature and ABA treatments.（3）A total of 5 lines of 35S: PpTST2-T transgenic tomato plants and 2 lines of transgenic apple calli of 2 transgenic varieties were identified by q RT-PCR technology and PCR technology.Overexpression of PpTST2-T in apple callus increased the total soluble sugar content of the callus.Then we detected the content of glucose,fructose and sucrose,all of which were increased.Transgenic tomatoes grew faster,bloomed earlier,had higher sugar content in leaves and fruit,decreased fruit organic acids,and increased 1000-kernel weight than wild-type tomatoes.（4）Overexpressing PpTST2-T tomato and the wild type were treated with drought stress.Physiological stress indicators the transgenic plants had better drought tolerance.The results showed that the content of malondialdehyde and relative conductivity in wild-type tomato plants were higher after drought treatment,while the content of chlorophyll,soluble protein and POD activity in transgenic tomato plants were higher.Which indicated that overexpression of PpTST2-T gene improved tomato tolerance to drought.（5）The yeast single-hybrid experiment identified that Pp ABRE1 could activate the expression of PpTST2,and the dual-luciferase assay further confirmed that Pp ABRE1 could activate the expression of PpTST2. |
