The 30th International Conference on Arabidopsis Research (ICAR 2019)

457 / 2019-02-26 15:24:11

MAS integrates ovular signals and exocytosis to guide pollen tube

membrane fusion,pollen tube,exocytosis,cell-to-cell communication

Plenary track > Cell Biology

Plants use Ca2+ signaling to trigger universal cellular signaling pathways in development and response to the environment. But how the extracellular signals are translated to trigger the Ca2+ flux is poorly understood. The pollen tube as an invasive growing cell is beaconed by diverse female signals and transduces these signals into the intracellular growth machineries, such as the Ca2+ signaling, for the navigation into the embryo sac. How the pollen tube realizes this molecular integration from outside to the inside Ca2+ dynamics for the guided growth is unknown and important to understand the reproduction and adaption strategies of plant cells. Here we report a mechanism for the directional exocytosis of cargos in pollen tube response to the female signals. Mutants of MALE SENSOR (MAS), which encodes a plasma membrane protein, show abnormal pollen tube response to the secreted ovular cues in Arabidopsis thaliana. Molecular and biochemical studies reveal that MAS selectively tether Ca2+-related cargos to the plasma membrane where the extracellular signals are perceived through the SNARE proteins in a trans mode. These results reveal a mechanism of molecular integration of extracellular cues and selective exocytosis, and will shed light on the general regulation of cell response to the environment.