Functional analysis of a novel male fertility CYP86MF gene in Chinese cabbage (Brassica campestris L. ssp chinensis makino)

In our earlier work, a cytochrome P450 CYP86MF gene was isolated from floral bud of Chinese cabbage (Brassica campestris L. ssp. chinensis Makino, syn. B. rapa L.) by mRNA differential display PCR (DD-PCR) and rapid amplification of cDNA ends (RACE). To unravel the biological function of CYP86MF gene, the antisense fragment from the CYP86MF gene was transferred into Chinese cabbage pak-choi (B. campestris ssp. chinensis var. communis Tsen et Lee). Out of 22 plants transformed with the antisense gene constructed from the CYP86MF, 20 reached to flowering stage. Morphological investigations showed that the transgenic plants developed the normal floral organ. However, they remained self-infertile, even when artificial self-pollination was performed in the bud stage. Pollen germination test indicated that the pollen from the transgenic line TB-2 could not germinate normally. Further physiological, biochemical and cytological analyses showed that only significant difference was detectable in contents of the endogenous hormones, and a layer of unknown material adhered to the surface of microspore. The present studies thus provided valuable clues for understanding the biological function of the CYP86C subfamily genes. Furthermore, our studies also demonstrate a novel method for obtaining artificial male sterility line of Chinese cabbage.