Abstract: Through the contrast of the stigma protein expression profiling between after self-pollination and none-pollination of Brasscia oleracea L. SI line A1，an up-regulated protein was identified，which was named BosiPA1 protein. The full-length DNA of this gene was 3 730 bp，and the ORF（open reading frame）was 1 092 bp. The gene contained six exons and five introns，encoded 363 amino acids，the amino acids sequence analysis showed that BosiPA1 contained a typical basic helix-loop-helix（bHLH）domains，which can recognize and bound the E-box（CANNTG）sequence. There are the E-box sequence in the promotersequences upstream of the ATG of SCR，SRK，Exo70A1. Phylogenetic tree analysis showed that Brassica oleracea L. BosiPA1 was most close to AtbHLH128，and grouped into one clade with AtHEC1/2/3 and TgGBOF-1. RT-PCR analysis indicated that BosiPA1 was expressed in petal，sepal，pollen，stigma and leaf，the further real-time fluorescence quantitative PCR analysis showed that the relative expression level of BosiPA1 in the stigma increased continually after 10 min，30 min，1 h self-pollination. All the results indicated that BosiPA1 may be a transcription factor related with SI and involved in multi-organs development in Brasscia oleracea L.

Key words: Brassica oleracea, bHLH transcription factor, gene cloning, expression analysis