Abstract: 【Objective】The objective was to clone genes encoding new MYB transcription factors,to analyze their sequences and to explore their function primarily.【Method】RT-PCR was used to isolate cDNA complete sequences of MYB genes and to analyze their expression in plants;The transcriptional activties of the MYB proteins were detected by yeast one-hybrid system.【Result】A pair of degenerate primers was designed according to the conserved regions which encode the MYB DNA binding domains in plant MYB genes. Two 168 bp fragments were amplified from the leaves of soybean (ZhongDou-27) using the method of RT-PCR. GmMYBZ1 and GmMYBZ2 , two new MYB genes were isolated by RACE method. The transcriptional activation abilities of GmMYBZ2 protein was confirmed by the yeast one-hybrid system,its β-galactosidase activity assayed to be 10.39. The resoults of quantitative RT-PCR showed that GmMYBZ2 gene was expressed in roots, stems, leaves and immature seeds of soybean, whereas GmMYBZ1 gene was expressed only in the stems and leaves. quantitative RT-PCR analysis indicated that the expression of GmMYBZ2 may also responses to UV-B radiation .【Conclusion】It was hypothesized that the conserved motif pdLNLD/ELXiG/S in the C-terminal region of GmMYBZ2 resulted in the weak transcriptional activation; The expression of GmMYBZ2 was downregulated by exposure to UV-B light.

Key words: Soybean, MYB transcription factors, gene expression and regulation