Functional characterization of BpMADS3 gene from Betula platyphylla.

In this study, we performed RT-PCR to compare expression level of BpMADS3 gene in different tissues of Betula platyphylla. The results showed that BpMADS3 was strongly expressed in inflorescences but not stem and leaves. A 1 426 bp sequence upstream of BpMADS3 gene was cloned from the genomic DNA of B. platyphylla by PCR based on the genome walking method. Transgenic Arabidopsis lines containing a BpMADS3 promoter: GUS construct were obtained, which only exhibited strong GUS staining in sepal and carpel. Overexpressed BpMADS3 in Arabidopsis ap1 mutant, the results showed the phenotype of ap1 was recovered. Ectopic expression of BpMADS3 significantly enhanced the flowering of transgenic tobacco, and the expression level of some flowering-related genes was significantly up-regulated in transgenic tobacco compared with the wild-type