Abstract
In the Brassicaceae, a compatible pollen grain adheres to and hydrates on a papilla cell of the stigma. The hydrated pollen grain germinates, and the pollen tube penetrates into the papilla cell wall to deliver the sperm cells to the embryo sac for fertilization. During cross-pollination, water and ions are transported from the papilla cell to the pollen grain. However, its mechanism is unclear. In this research, we characterized the water channels, which are essential for pollen hydration. First, pharmacological analysis using HgCl2, an inhibitor of aquaporin, suggested that the stigmatic aquaporin(s) are involved in the water supply. Next, we identified aquaporins, which are highly expressed in stigmatic papilla cells, by micro array. We also examined the molecular dynamics of these aquaporins during pollination by expressing Venus fusions in the papilla cells.
