Abstract
The pollen coats are sticky substances composed of lipids and proteins, covering the surfaces of pollen grains of many higher plants. They are believed to have many roles in pollen function, such as adhesion to pollinators and stigmas, recognition by stigmas, and water transport for pollen germination. The EXTRACELLULAR LIPASE4/6 (EXL4/6) and GLYCINE-RICH PROTEIN17 (GRP17) are two major proteins in Arabidopsis pollen coat, and are necessary for complete fertility of pollen grains. To examine the mechanism how these proteins synthesized in tapetal cells are incorporated into pollen coat, we started to analyze the subcellular localization of EXL4-GFP fusion protein in Arabidopsis and Brassica tapetal cells. It has been established that the GRP17 is accumulated in tapetosomes, which are specific oil-accumulating organelles in tapetal cells. The developing tapetosomes in Brassica anthers were visualized by GRP17-GFP protein. We attempted to isolate the tapetosomes by affinity purification using GFP antibody.
