Abstract

Plant MYB Transcription factors play important roles in defense responses. We described here a novel gene BrMyb encoding MYB transcription factor homologue was isolated from Erwinia carotovora subsp. Carotovora (Ecc) pathogens diseased Chinese cabbage (Brassica rapa subsp. pekinensis) and named as BrMyb. The nucleotide sequence of the cloned BrMyb revealed a single open reading frame of 1047 bp coding for 348 amino acids with a theoretical protein size of 48 kDa. The deduced amino acid sequence showed significant homology with Brassica oleracea brassica MYB protein and Arabidopsis thaliana minor MYB protein by 89.2 and 81.2% amino acid sequence identity, respectively. The protein showed significant alignments with a SANT/Myb DNA binding domain in members of MYB family proteins from dicotyledon and monocotyledon. The expression of BrMyb could be detected in developmental leafstalks and enhanced by Ecc infection, injury, methyl jasmonic acid and salicylic acid treatments, respectively. These results suggested that BrMyb might be an old plant gene, and plays roles not only in plant development but also in the response to pathogen infection and other stresses.

Key words: Transcription factor, Erwinia carotovora subsp. carotovora, Brassica rapa subsp. pekinensis, methyl jasmonic acid, salicylic acid.