The ability to tolerate saline conditions is a variable and complex trait in plants. Salinity tolerance includes the ability to respond to osmotic stress and resistance to toxicity of individual ions. These traits are significant in determining the natural distribution of plants, and are important in agriculture, because salinity may limit productivity, especially in irrigated soils. The study will be done on Charophytes, complex macrophytic algae closely related to the line which gave rise to higher plants. These algae have large internodal cells, permitting experimental manipulations not possible in other plants. Two closely related species, Chara corallina, an obligate freshwater species, and C. buckellii, a species collected from a salt lake which can be cultured in fresh or salt water will be studied. The two species differ in their ability to regulate turgor and in their tolerance to sodium and magnesium. Dr. Bisson will study ion fluxes and the mechanism by which they occur in intact cells, cells with permeabilized plasmalemma, cells whose internal contents have been perfused away and replaced by controlled solutions, isolated vesicles of membrane, and patches of membrane. The aim is to elucidate the mechanism of movement and how this movement is controlled by environmental and cytoplasmic factors to confer resistance to salt toxicity.//
