Functional analysis of a pollen-expressed polygalacturonase gene BcMF6 in Chinese cabbage (Brassica campestris L. ssp. chinensis Makino).

In our earlier work, a pollen-expressed polygalacturonase gene BcMF6 was isolated from floral bud of Chinese cabbage (Brassica campestris L. ssp. chinensis Makino) by cDNA-amplified fragment length polymorphism (cDNA-AFLP) transcript profiling and rapid amplification of cDNA ends (RACE). To unravel the biological function of BcMF6 gene, the antisense fragment from the BcMF6 gene with A9 promoter and CaMV35S promoter was transferred into flowering Chinese cabbage (B. campestris ssp. chinensis var. parachinensis). Out of transgenic plants transformed with the antisense gene constructed from the BcMF6, transgenic line with A9 promoter have a similar appearance to that with CaMV35S promoter. Morphological investigations showed that the transgenic plants developed the smaller floral organ with thin anther and less pollen. Pollen germination test indicated that only near 50% the pollen from the transgenic line could normally germinate. Further scanning electron microspore analysis of transgenic plants confirmed that half of pollen was abnormal. Cytological comparisons of microspore development also demonstrated that process of microsporogenesis was held up, microspores maturation was disrupted and pollen grain fail to separate, finally. In a word, the present study revealed that BcMF6, as a polygalacturonase gene, has a role in pollen maturation and pollen tube growth.