Sy. Park et al., A lipid transfer-like protein is necessary for lily pollen tube adhesion to an in vitro stylar matrix, PL CELL, 12(1), 2000, pp. 151-163
Flowering plants possess specialized extracellular matrices in the female o
rgans of the flower that support pollen tube growth and sperm cell transfer
along the transmitting tract of the gynoecium. Transport of the pollen tub
e cell and the sperm cells involves a cell adhesion and migration event in
species such as lily that possess a transmitting tract epidermis in the sti
gma, style, and ovary. A bioassay for adhesion was used to isolate from the
lily stigma/stylar exudate the components that are responsible for in vivo
pollen tube adhesion. At least two stylar components are necessary for adh
esion: a large molecule and a small (9 kD) protein. In combination, the two
molecules induced adhesion of pollen tubes to an artificial stylar matrix
in vitro. The 9-kD protein was purified, and its corresponding cDNA was clo
ned. This molecule shares some similarity with plant lipid transfer protein
s. Immunolocalization data support its role in facilitating adhesion of pol
len tubes to the stylar transmitting tract epidermis.