The natural tomato mutant 'Firme' from cv. Santa Clara presents a yellow-pale appearance when immature, firm texture and slow ripening. Some of the physiological changes throughout ripening of cv. Santa Clara and the natural mutant 'Firme' were evaluated on the vine. Fruit ethylene and CO2 production, locular and outer pericarp total soluble sugars content, ACC oxidase and poligalacturonase activities were evaluated in both genotypes at six maturity stages. Mutant fruits presented lower ethylene and CO2 production at all maturity stages. ACC oxidase activity showed a distinct pattern during ripening of the wild type and mutant fruits, nevertheless, the mutant and wild type presented similar final activity. Mutant fruits showed delay in the increment of poligalacturonase activity compared to wild type fruits at the onset of ripening. While the wild type fruits showed continuous rise in total soluble sugars through ripening, the mutant fruits showed trends of decrease. Mutant fruits had lower content of total soluble sugars in the outer pericarp at later stages of ripening.
Lycopersicon esculentum; ethylene; respiration; soluble sugars; ACC oxidase; poligalacturonase
