Regulation by Carbon Dioxide of Wound-induced Ethylene Biosynthesis in the Peel of Citrus Fruit

Abstract

The effect of carbon dioxide (CO2) on wound-induced ethylene biosynthesis in flavedo discs of mature orange fruits (Citrus sinensis L. Osbeck) is investigated. Wounding induced a marked and rapid increase on the rate of ethylene production, the content of 1-aminocyclopropane-1-carboxylic acid (ACC) and on the in vivo ACC oxidase (ACO) activity. Incubation of flavedo discs in a 15% CO2 atmosphere suppressed activation of these processes. Wound-induced ethylene production was inhibited by CO2 in a concentration-dependent manner but ACO activity was enhanced at concentrations between 1% and 5%. Kinetic analysis of the interaction between CO2 and ACO activity indicated that high CO2 acted as a noncompetitive inhibitor. Removal of CO2 after 24 h incubation did not restore normal rates of ethylene production. CO2 partially counteracted the increase in ethylene production and ACO activity induced by a pretreatment with an ethylene action inhibitor (STS, silver thiosulfate). This suggested that part of CO2 action on ethylene biosynthesis might be due to interfering ethylene action. Collectively, the results indicated that ACS activity appeared to be the major regulatory step by which CO2 suppresses wound-induced ethylene production. ACO was differentially modulated by CO2, which is being stimulated at low concentrations and inhibited at high concentrations.

Effects of Heat Treatment on Wound Healing in Gala and Red Fuji Apple Fruits

“…Thus, ethylene production is an indicator of wound healing. Previous study had shown that wounding induced a marked and rapid increase in the rate of ethylene production in citrus fruits (21). In this study, we found that the ethylene evolution of wounded Gala or Red Fuji apples in the control group (W-CK) sharply increased during the treatment (Figure 2A and B).…”

Biosíntesis de Carotenoides durante la Conservación Postcosecha de Frutos Citricos

“…Estudios de expresión génica en el flavedo de frutos cítricos indican que el etileno estimula y acelera algunos de los cambios que se producen durante la maduración natural del fruto (Trebitsh et al, 1993;Alonso et al, 1995;Zacarías y Alférez, 2007), pero no se puede concluir que el etileno sea el regulador natural de estos cambios. Dado el carácter no climatérico de los frutos cítricos, se ha sugerido que el papel de la hormona durante la maduración podría ejercerse mediante cambios en la sensibilidad a la misma (Alonso et al, 1995).…”