Abstract:

【Objective】 This paper aims at cloning a pectin methylesterase gene in order to provide assistance to study the roles of the pectin metabolism in the fertility regulation of Chinese cabbage.【Method】Analysis of gene differential expression was performed by cDNA-AFLP in the genic male sterile line ‘AB02’of Chinese cabbage, and a differentially expressed cDNA fragment, TDF-24, was found only in fertile plants. The full-length cDNA of the gene related to TDF-24 was amplified by RACE and RT-PCR, and the characteristics of the deduced protein were analyzed using bioinformatics softwares. Gene expression characteristics were proved by Real-time PCR 【Result】 The novel pectin methylesterase (PME,EC 3.1.1.11) cDNA(BrPME1, GenBank accession number HM185497), was isolated from Chinese cabbage. The cDNA was 1 290 bp long, encoding a putative preprotein of 363 amino acids with a signal peptide of 23 amino acids, which contains ten phosphorylation sites, six N-myristoylation site, one amidation site and one conserved PME domain, but no PMEI (pectin methylesterase inhibitor) site. BrPME1 was highly expressed in big flower buds and mature anthers of fertile plants, with an extremely low expression level in sterile buds.【Conclusion】 The results indicated that BrPME1 is a member of the PME gene family inhibited by genic male sterile gene in Chinese cabbage.

Key words: Chinese cabbage [Brassica campestris L. ssp. pekinensis(Lour.)Olsson, multiple allele, genic male sterility, pectin methylesterase, gene expression