Session 3, 2 p.m.:

Abstract: Since 1900, the most widely-accepted model for plant gravity sensing has been the starch-statolith model which proposes that sedimenting intracellular particles are the gravity sensors. A shortcoming of this model is that there are examples of gravity-responsive plants and plant tissues which do not contain sedimenting statoliths. We proposed an alternative model for plant gravity sensing (the gravitational pressure model) in which the entire protoplast is suggested to be the gravity sensor and that the gravity signal is perceived by sensing differential pressure between the protoplast and the extracellular matrix at the top and the bottom of the cell. I will summarize data from experiments designed to distinguish between these models.