Changes in the relaxation times of water protons in fungal cells indicate fungicide effects on membrane water permeability

Abstract

Water proton spin-lattice relaxation times and spin-spin relaxation times were measured in the mycelial cells of Botrytis cinerea. The relaxation patterns show that the cellular water consists of two components. The major water component has longer relaxation times and this is considered to be the cytoplasmic water. The minor component with shorter relaxation times is considered to be the cell wall hydration water and the water between the cell wall and the cell membrane. When the mycelia were treated with three kinds of fungicides, benomyl, edifenphos, and procymidone, the relaxation times of the major water component decreased. Changes in the amounts of cellular water, soluble protein, soluble saccharide, and soluble paramagnetic metals by the fungicide treatments are not large enough to account for the shorter relaxation times. Acceleration of water exchange through the membrane as a result of increased membrane permeability is considered to be the primary cause of relaxation time shortening by fungicides.