The Function Of BpTCP11 And BpTCP19 Genes On The Regulation Of Leaf Senescence In Betula Platyphylla

TCP was a plant-specific type of transcription factor.Members of this family were involved in the development of leaf and flower organs,the differentiation and formation of ductal xylem duct molecules,and stress response processes.In this study,the expression patterns of BpTCP11 and BpTCP19 genes were analyzed,and plant overexpression vector was constructed and genetic transformation was carried out..The leaf senescence was carried out on the transgenic bptcp19 gene lines,and the downstream regulatory genes were identified by transcriptome and yeast single hybrid to reveal the leaf senescenceand provide theoretical support for post-woody plants to leaf senescence.The results were as follows:1.The expressions of two PCF subclass genes BpTCP11 and BpTCP19 in different tissues(leaf,terminal bud,axillary bud,tender stem,xylem and phloem),leaves and stem nodes at different developmental stages.and their response patterns to different hormone and abiotic stress were analyzed by qPCR.T The analysis results showed that BpTCP11 and BpTCP19 genes were highly expressed in the xylem and phloem of Birch;they showed similar expression patterns in leaves and stem nodes at different developmental stages,and responded to a variety of hormones and abiotic resistance responses.2.Gateway technology was used to construct plant overexpression vectors for BpTCP11 and BpTCP19 genes.The Agrobacterium-mediated transformation was used to genetically transform B.platyphylla,and finally 6 transgenic BpTCP11 overexpressing transgenic lines and 6 transgenic BpTCP19 overexpressing transgenic lines were successfully obtained.Seedling height,ground diameter,pitch,leaf morphology and endogenous hormones of BpTCP19 over-expressed and WT lines were measured.The results showed that the leaf lengthleaf width,seedling height,ground diameter,and node spacing of most transgenic lines became larger than those of WT lines,and the chlorophyll content was significantly higher than that of WT lines,endogenous IAA and JA contents were higher than WT lines,and ABA contents were lower than WT lines.3.Leaf senescence of BpTCP19 over-expressing lines were induced by dark,the SOD activity,H2O2 content,and chlorophyll changes of each line were measured,and DAB and NBT staining were performed;In addition,under dark and hormone treatments,chlorophyll content,and the expression patterns of genes related to senescence,chlorophyll catabolism and hormone signal transduction on the leaves of transgenic and WT lines were analyzed.The results showed that after dark treatment,the leaves of the over-expressing lines showed a delayed senescence.WT lines showed a larger amount of H2O2 and O2-accumulation than transgenic lines.At the same time,the SOD and H2O2 contents also changed significantly.Under dark,ABA,JA,and ACC treatments,compared with the WT line,the leaves of the transgenic line showed green characteristics,and the expression levels of senescence and chlorophyll degradation genes were lower than those of WT line.Under SA treatment,there was no significant difference between the lines.4.Transcriptome libraries of young and functional leaves of BpTCP19 overexpression and WT lines were established,respectively.The differentially expressed genes of the transgenic and control lines in the two tissue sites were 2519 and 3316,respectively,and the expression levels of genes related to the pathways were changed,such as cell cycle,defense mechanism,and hormone signal transduction5.The BpTCP19 gene was cloned into the effector vector pGADT7-rec2 vector,and the proBpWRKY53 and proBpNAC2 sequences containing the TCP binding element were constructed into a reporter vector.Through yeast one-hybrid screening,it was found that the BpTCP19 transcription factor can bind to the BpWRKY53 promoter region.