Malic enzyme and cyanide-resistant respiration in mango during ripening.
Reddy V. V., Srivastava G. C.
Author Affiliation: Division of Plant Physiology, Indian Agricultural Research Institute, New Delhi-110 012, India.
Indian Journal of Plant Physiology 3 : 185-187
Abstract : Respiration and malic enzyme activity were measured in mature green, partially ripe, ripe and full ripe fruits of mango cultivars Amrapali and Dashehari. Total respiration increased during ripening of fruits up to the ripe stage, after which it declined. Cyanide-resistant respiration peaked and was the biggest individual contributor to total respiration at the partially ripe and ripe stages, the opposite trend to that of cytochrome respiration. A considerable amount of residual respiration was also recorded at the partially ripe and ripe stages. Malic enzyme activity increased gradually from the mature green to the ripe stage and decreased thereafter. It is suggested that the increased activity of malic enzyme at the partially ripe and ripe stages provides a substrate for the respiratory pathway, leading to high reducing power, which may stimulate alternate oxidase and other oxygenases to accept electrons and further reduce oxygen to water.