Water Permeability during Tomato Fruit Development in Normal and rin Nonripening Mutant.

This work tested one aspect of the relations between membrane permeability and fruit ripening. Membrane permeability was measured as [(3)H]water efflux rate from preloaded fruit pericarp disks. Different stages of fruit development were compared between two tomato (Lycopersicon esculentum Mill) strains: the normal Rutgers and the isogenic nonripening rin strain. The first significant increase in permeability was measured in Rutgers tissue at 110% of development, after fruit ripening had already begun as indicated by ethylene and CO(2) evolution and lycopene synthesis. The rin did not show any increase in tissue permeability during fruit development or maturation.Our results do not support the idea that the first event of the ripening process is an increase in membrane permeability. Nevertheless, the nonripening mutant fails to show the normal increase in permeability.