Members of the arabinogalactan protein (AGP) gene family have important functions in plant growth and development, especially in plant reproduction. Lin et al. examine expression of Brassica campestris male fertility 8 (BcMF8) in pistils of Chinese cabbage (B. campestris ssp. chinensis), and find that it encodes a putative AGP that is located in the cell wall and is expressed in pollen grains and pollen tubes. Functional interruption of BcMF8 by antisense RNA technology results in misshapen pollen with abnormal intine development and aperture formation, and a decrease in germination percentage. Where germination does occur, pollen tubes are unstable, abnormally shaped and burst more frequently relative to controls. The results suggest a crucial function of BcMF8 in modulating the physical nature of the growing pollen tube wall and in helping to maintain the integrity of the tube wall matrix.