9422615 Thompson The phloem tissue plays a central role in the long-distance transport of carbohydrates, hormones, amino acids, and other organic compounds that are essential for plant growth. A further understanding of the molecular basis for the structural and physiological changes that occur during phloem differentiation will provide a basis for the development of innovative methods to improve plant growth and productivity. P-proteins are an intergral component of sieve elements in most plants, however the significance of these proteins in phloem development and function has not been experimentally tested. The ultimate goal of this proposed project is to determine the role(s) of two P- proteins, PP1 and PP2, in phloem physiology. Dr. Thompson will test the hypotheqis that P-protein filaments plug wounded sieve elements maintaining turgor within the sieve tube to preserve the functional integrity of the phloem. The proposed experiments are also designed to evaluate physiological roles for P-proteins during phloem differentiation in unwounded plants.
