BcMF23a contributes to pollen wall development via influencing intine construction, which, in turn, influences pollen tube growth. Pollen wall, the morphological out face of pollen, surrounds male gametophyte and plays an important role in plant reproduction. Pectin methylesterases (PMEs) are involved in pollen wall construction by de-esterifying pectin of the intine. In this study, the function of a putative pectin methylesterase gene, Brassica campestris Male Fertility 23a (BcMF23a), was investigated. Knockdown of BcMF23a by artificial microRNA (amiRNA) technology resulted in abnormal pollen intine formation outside of the germinal furrows at the binucleate stage. At the trinucleate stage, 20.69% of pollen possessed the degradation of nuclei, cytoplasm and the intine, resulting in shrunken pollen, whereas the remaining 75.86% were wall-disrupted with degrading cytoplasm and broken exine inside the germinal furrows. In addition, pollen abortion in transgenic plants caused germination percentage reduction by 19% in vitro and pollen tube growth disruption in natural stigma in vivo. Taken together, BcMF23a is involved in pollen development and pollen tube growth, possibly via participating in intine construction. This study may contribute towards understanding the function of pollen-specific PMEs and the molecular regulatory network of pollen wall development.
Keywords: Brassica campestris; Intine; PMEs; Pectin methylesterases; Pollen development; Pollen tube.