THE EFFECTS OF GA(3) AND DIVALENT-CATIONS ON ASPECTS OF PECTIN METABOLISM AND TISSUE SOFTENING IN RIPENING TOMATO PERICARP

The ripening of discs cut from the pericarp of green tomato (Lycopersi con esculentum Mill.) fruits is inhibited by;treatments with GA(3) and several divalent cations, including calcium. Normal ripening:is marke d by an increase in the solubility of wall pectins. Calcium and GA(3) alter the pattern of pectin solubility changes. In part this may be be cause polygalacturonase synthesis and/or secretion to the apoplast is reduced. The impact of divalent cations on ripening-related tissue sof tening appears to have a nonmetabolic component. Ripening-inhibiting i ons rapidly reduce tissue softening, pectin solubilization and the nor mal ripening-related decrease in cellular turgor.