Function Analysis Of BpSPL9 Gene In Betula Platyphylla

SQUAMOSA PROMOTER BINDING PROTEIN-LIKE(SPL)gene encodes a plant-specific transcription factor,and participates in the process of plant responses to biotic and abiotic stress in herbaceous plant.However,the function of SPL was less revealed in woody plant.In this study,Birch BpSPL9 gene was constructed into an overexpression vector,and integrated into the birch genome using genetic transformation.To verify the role of Birch BpSPL9 gene,salt and drought stress were carried on to the transgenic lines.The main research included:1.Based on 45 Birch transcriptome database,12 BpSPL genes were obtained and bioinformatics were analyzed,the results showed that genetic characteristics of Birch BpSPL were difference,ranging from the number of intron and exon,the genes were distributed in 8 chromosomes of Birch.All genes contained a typical SBP domain.7 of Birch BpSPL genes had the sites recognized by miR156.2.Using real-time quantitative PCR,expression patterns of 12 BpSPL gene were analyzed in leaves,buds,stems,male inflorescences and female inflorescences of birch.The expression patterns in different tissues were different,the genes with highly homologous shared with similar expression patterns.The expressions of miR156 and its targets BpSPL genes were certain interaction in buds,stems and male inflorescences.The expression of BpSPL9 gene in roots and leaves had changed under NaCl and PEG treatments,suggested that BpSPL9 was involved in the stress response.3.Appling Gateway technology,a plant overexpression vector containing BpSPL9 gene was constructed and transformed into birch via agrobacterium tumefaciens-mediated.The transgenic plants were identified by PCR,Q-PCR and Northern blotting analysis,the result showed that BpSPL9 gene was successfully integrated into the plant genome and expressed steady.The gene expression levels of BpSPL9 transgenic lines was far higher than the non-transgenic lines.4.Birch transgenic and non-transgenic lines were implemented 1.0%NaCl and 15%PEG stress treatment.DBA and NBT staining analysis,the activity of SOD and POD and the content of H2O2 were measured under different conditions of stress treatments.The results showed that,transgenic lines showed higher stress resistance than non-transgenic lines under abiotic stress conditions.