Functional Analysis of a Novel Male Fertility Lipid Transfer Protein Gene in Brassica campestris ssp. chinensis

In our previous work, a novel gene ( BcMF15 ) encoding a lipid transfer protein (LTP) was isolated from floral buds of Chinese cabbage pak choi ( Brassica campestris ssp. chinensis , syn. B. rapa ssp. chinensis ) by cDNA-amplified fragment length polymorphism transcript profiling and rapid amplification of cDNA ends PCR. This LTP gene was exclusively expressed in the fertile line, indicating that this gene was related to male sterility. Functional analysis by RNA interference showed aberrant development and precocious degeneration of the tapetum. Pollen germination tests indicated that only 36 % of pollen from the transgenic lines can normally germinate. Morphological investigations showed that the transgenic plants developed smaller floral organs with thin anthers and lower amounts of pollen. Scanning electron microscopy revealed that the transgenic plants had higher numbers of abnormal pollen grains. Histological observations also demonstrated that microsporogenesis was suppressed and resulted in the failure of microspore maturation. These results demonstrated that BcMF15 played a major role in tapetum development, thereby providing valuable information on the biological function of LTP genes during pollen development.