Isolation And Functional Analysis Of The BpCUC2 Gene And Its Promoter In Betula Pendula

CUP-SHAPED COTYLEDON 2 (CUC2), a member of the plant-specific NAC transcription factor family, is required for shoot apical meristem (SAM) formation and specification of the organ boundary. In recent years, it has attracted more and more attention. However, the study of the CUC2 gene almost focused on the model plant Arabidopsis thaliana and some other cash crops. So far, it has not been reported on woody plants. To help people learn more about the exact mechanism of growth and development of Betula pendula and use the BpCUC2 gene to rebuild plant form, in this research, we preliminary analysis function and expression profiles of the BpCUC2 gene in Betula pendula.In this research, first, we clone the BpCUC2 gene using PCR technology, construct the plant expression vector containing the CaMV 35S strong promoter and analyze the gene sequence. Next, a real-time PCR is used to quantify the BpCUC2 gene expression of different tissues of half-year-old Betula pendula seedlings. Then, we clone the BpCUC2 gene promoter from the gDNA of Betula pendula, connect it with the Luc2 reporter gene and fuse it into Arabidopsis thaliana. Using the plant imaging system, we analyze the tissue specificity of the BpCUC2 gene expression. At last, we fuse the BpCUC2 gene into Arabidopsis thaliana and observe the phenotype changes of the transgenic Arabidopsis thaliana strains which have high-level expression of the BpCUC2 gene.The results indicate that:1.Forecast showed that the BpCUC2 gene contained three exons and two introns,2126bp of full-length sequence,52bp of 5’UTR,204bp of 3’UTR and 1065 bp of CDS.2. There was a significant difference of the BpCUC2 gene expression among different tissues of Betula pendula seedlings. In descending order, the expression level of the BpCUC2 gene were stem tips, stems, roots and leaves, and the expression of stem tips was 6 times higher than that of leaves.3. The BpCUC2 core promoter only contained TATA box and initiator, and the whole promoter sequence also had so many kinds of cis-acting elements, including tissue specific expression, phytohormone and environmental stress response, transcription factor binding, etc.4. The BpCUC2 promoter drove the Luc2 reporter gene to express in SAM, leaf margins and flowers, of which the expression in SAM was the highest.5. The phenotype of BpCUC2-overexpressing plants exhibited multiple SAMs, divided cotyledons, increased rosette leaves and main stems, smaller organs, shrunken plant height, delayed development etc.The results suggest that the BpCUC2 gene mainly expresses in meristem. Throughout the growth cycle of Betula pendula, it plays an important role.