| Begonia semperflorens is a perennial herbaceous flower of great value in the landscape,but is subject to a variety of abiotic stresses during growth and reproduction.At present,most of the research on Begonia semperflorens is focused on cultivation and propagation,pest and disease control and biological characteristics,but there are few reports on its molecular regulation mechanism,cultivation of good traits,acquisition of important genes and functional research under adversity stress.In this study,the location of MYB62 protein in Begonia semperflorens was determined by subcellular localization analysis;then the tissue-specific analysis of Bs MYB62 gene was performed by fluorescence quantitative PCR.In addition,an overexpression vector for the gene in plants was constructed,and Arabidopsis thaliana was heterologously transformed by inflorescence infiltration,and finally a transgenic pure Arabidopsis thaliana strain overexpressed by the Bs MYB62 gene was obtained,which laid the foundation for the functional study of Bs MYB62 gene at a later stage.The relevant results of this study are as follows:1.The RNA was extracted from leaves,roots,stems,male flowers and female flowers of Begonia semperflorens plants for fluorescence quantitative PCR assays.The results showed that Bs MYB62 gene was expressed in five tissue sites of Begonia semperflorens.Among them,the expression level is the highest in the stem,followed by the root,female flower and male flower,and the expression level in the leaf is the lowest.2.The GFP expression vector of MYB62 protein in Begonia semperflorens and the nuclear Marker protein expression vector as a control were successfully obtained,and they were transiently expressed in tobacco leaves.The fluorescence distribution was observed by laser confocal microscopy,and the results showed that the fluorescence signal of the MYB62 protein was localized to the nucleus of Begonia semperflorens.3.An overexpression vector of Bs MYB62 gene was constructed,and the target gene was transferred into wild-type Arabidopsis thaliana by Agrobacterium-infected inflorescence method to obtain a transgenic Arabidopsis thaliana line with Bs MYB62 overexpression.Finally,the T3 homozygous line of Arabidopsis thaliana overexpressing Bs MYB62 was successfully screened using hygromycin-resistant medium,and it was used for subsequent gene function study.4.From the response of Bs MYB62 transgenic Arabidopsis thaliana to drought stress during germination,it was found that overexpression of Bs MYB62 gene made transgenic Arabidopsis thaliana grow better than wild-type Arabidopsis thaliana under drought stress,and also promoted the germination of transgenic Arabidopsis thaliana seeds and the growth of primary as well as lateral roots,which significantly enhanced the tolerance of Arabidopsis thaliana to drought stress during germination.Drought stress on Arabidopsis thaliana seedlings revealed that plants of three Bs MYB62 overexpression lines were less damaged compared to wild-type Arabidopsis thaliana.The Fv/Fm of all strains gradually decreased under drought stress,and the Fv/Fm of the three overexpression strains was always higher than that of wild-type Arabidopsis thaliana,indicating that the Bs MYB62 gene could improve the photosynthetic potential and stress resistance of Arabidopsis thaliana.In addition,chlorophyll content,proline(Pro)content,and superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)activities were significantly higher in the three overexpression lines than in wild-type Arabidopsis thaliana after drought stress,while malondialdehyde(MDA)content was much lower than in wild-type Arabidopsis thaliana.The above results indicate that the transgenic strain has a stronger ability to scavenge reactive oxygen species during drought stress,making its damage by drought stress lower than that of wild-type Arabidopsis thaliana,which indicates that overexpression of Bs MYB62 gene can improve the drought resistance of transgenic Arabidopsis thaliana.5.The relative expression of Bs MYB62 gene in the three overexpression lines under drought stress was found to be increasing by fluorescence quantitative PCR assay,and the Bs MYB62 gene was significantly induced under drought stress,suggesting that Bs MYB62 gene was involved in the drought stress response process in Arabidopsis thaliana.6.The response test of Bs MYB62 transgenic Arabidopsis thaliana to salt stress revealed that overexpression of Bs MYB62 gene can improve the seed germination rate and promote the growth of primary roots in Arabidopsis thaliana under salt stress.7.From the response test of Bs MYB62 transgenic Arabidopsis thaliana to low phosphorus stress,it was found that overexpression of Bs MYB62 gene increased the germination rate of Arabidopsis thaliana seeds under low phosphorus conditions,and promoted the growth of Arabidopsis thaliana taproot,lateral roots and root hairs.thus suggesting that the Bs MYB62 transgenic lines may have stronger resistance to low phosphorus stress than wild-type Arabidopsis thaliana. |
