Action of the Ripening Inhibitor (rin) on Fruit Ripening of Tomato

Abstract

The experiment was carried out to clarify the physiology of the fruit ripening regulated by ripening inhibitor gene, rin, of tomato (Lycopersicon esculentum Mill.). Changes in respiration, ethylene production, and ABA, IAA, soluble carbohydorate, titratable acid and free amino acid contents during ripening were investigated in detached fruits of tomato cv.‘Rutgers’and its nearly isogenic rin mutant stock.
1. Maximum production rates of carbon dioxide and ethylene production from ‘Rutgers’fruit were observed during storage but rin fruit showed little change in the production rates of carbon dioxide evolution and low rates of ethylene production.
2. Free ABA content in pericarp tissue during storage gradually increased and reached peak levels 9 days after harvest (dark pink stage) in both‘Rutgers’and rin fruits. Its content was higher in rin rather than in‘Rutgers’fruits. Bound ABA content changed in parallel with free ABA content in pericarp tissues of both ‘Rutgers’and rin although the former was always lower than the latter.
3. IAA in pericarp tissue increased during storage and reached a maximum level at dark pink stage of ripeness in‘Rutgers’fruit but, in rin fruit, only traces of it were observed.
4. Soluble carbohydorate and titratable acid content in pericarp tissue decreased during storage and no differences were observed between‘Rutgers’and rin fruits.
5. The predominant free amino acids in pericarp tissue during storage were aspartic acid, threonine+serine fraction, glutamic acid, phenylalanine and γ-amino-butyric acid. Contents of aspartic acid and glutamic acid progressively increased during storage in both‘Rutgers’and rin. In other amino acids, little changes were observed.