Molecular Mechanisms Underlying A GPI-anchored Protein(COBL-10)-Regulated Pollen Tube Growth And Guidance

Reproduction of flowering plants requires successful pollination and fertilization, in which pollen tube growth is a key step. The cylindrical shape of pollen tubes, similar to that of root hairs and fungal hyphae, results from asymmetric cell expansion called tip growth in which elongation is restricted to a small area at the surface of the cell. Pollen tubes could growth in vitro in media of simple compositions but achieve rapid growth when grow inside nutrient-rich pistils. In addition, pollen tubes could sense female guidance cue and change their growth directions accordingly. A deep understanding of this fascinating process is not only potentially important for crop genetic engineering but also help answer some fundamental biological questions such as asymmetric cell growth and cell-cell communication. COBL10is a glycosylphosphatidylinositol-anchored protein (GPI-AP) that belongs to a plant-specific GPI-AP family. We found out that its mutants are defective in pollen tube in vivo growth. We found the molecular mechanisms underlying COBL10-regulated pollen tube in vivo growth. Furthermore, GPI-APs exist in large numbers in eukaroytes. Although a few GPI-APs were reported by mutational studies, there is hardly any information regarding their processing, subcellular localization and genetic networks in which they function. Therefore, we used COBL10to explore these neglected but critical aspects. Knowledge gained from this study will not only provide a better understanding of signaling networks regulating pollen tube-pistil interaction but also provide a case study for a large number of functional unknown GPI-APs in plant.