Abstract: On the basis of one cDNA-AFLP differential fragment isolated from the fertile Bline of
Chinese cabbage-pak-choi (Brassica campestris L. ssp. chinensis Makino) nuclear recessive sterile A /B line
(Bajh97201A /B) , the full length DNA and cDNA of BcMF6 gene encoding pollen2specific polygalacturonase
were cloned by rapid amplification of cDNA ends (RACE). The gene consisted of 1 194 bp encoding a
protein of 397 amino acids and was interrup ted by three introns of 81 bp, 95 bp and 127 bp in length.
Sequence analysis revealed that it has three N-glycosylation sites, four protein kinase Cphosphorylation site,
five casein kinaseⅡphosphorylation site, ten N-myristoylation sites and one polygalacturonase active position
(²²⁷RVTCGPGHGIS1 IGS²⁴⁰ ). And the first 22 amino acids of the predicted BcMF6 protein form a N-terminal
hydrophobic domain which disp layed the p roperties of a signal peptide and four parallel beta-helix repeats
followed behind. Four domains which were highly conserved in all p lant and fungal PGs was p resent in
BcMF6. Phylogenetic analysis showed that BcMF6 falls into the category of clade2C, which included PG
related to pollen. These results showed that BcMF6 acts as pollen-specific polygalacturonase. Furthermore,
the exp ression using RT-PCR discovered that BcMF6 was exclusively exp ressed in middle and big flower bud,opened flower and slow pod of fertile line (wild type) , which showed BcMF6 closely related with the develop
ment of flower.

Key words: Chinese cabbage-pak-choi, Brassica campestris ssp. chinensis, BcMF6, Pollen, Polygalacturonase, Clone