The effects of GA3 and divalent cations on aspects of pectin metabolism and tissue softening in ripening tomato pericarp

Abstract

The ripening of discs cut from the pericarp of green tomato (Lycopersicon esculentum Mill.) fruits is inhibited by treatments with GA3 and several divalent cations, including calcium. Normal ripening is marked by an increase in the solubility of wall pectins. Calcium and GA3 alter the pattern of pectin solubility changes. In part this may be because polygalacturonase synthesis and/or secretion to the apoplast is reduced. The impact of divalent cations on ripening-related tissue softening appears to have a nonmetabolic component. Ripening-inhibiting ions rapidly reduce tissue softening, pectin solubilization and the normal ripening-related decrease in cellular turgor