The Respiration Climacteric in Apple Fruits

Abstract

SUMMARYThe activities of various mitochondrial enzymes in the peel of apples picked before the climacteric peak in respiration (R), were followed throughout the development of the climacteric in storage at 12° C; they showed an increase to the climacteric peak and beyond. In pulp tissue the peak values for mitochondrial activity occurred several days before the peak value of R. The soluble enzyme, malic enzyme (M.E.), reached a maximum in both peel and pulp at a point very close to the maximum value of R, while pyruvic carboxylase continued to rise past the climacteric peak.In fruit picked during the development of the climacteric on the tree and stored at 12° C, mitochondrial activity tended to follow changes in R; in the pulp a falling rate of mitochondrial activity probably commenced somewhat before the commencement of a fall in R. M.E. activity increased rapidly on picking in the early stages of the climacteric but little further increase occurred either in peel or pulp when fruit was picked near the point of maximum activity on the tree. This maximum activity on the tree was reached well before the peak in R and corresponded in time with the maximum rate of R ever reached in detached fruit.It is concluded that an increase in activity of M.E. and carboxylase is largely responsible for the climacteric rise in R up to the maximum rate attained in detached fruit, and that the excess respiration above this value 'on' the tree stems from other sources.

Volatile Ester Suppression and Recovery following 1-Methylcyclopropene Application to Apple Fruit

“…The preclimacteric and climacteric rates of CO 2 production reported are similar to those reported previously (Hulme, 1954;Hulme et al, 1963;Jones et al, 1965;Looney, 1969). Ethylene production rates are similarly consistent with previous research (Saftner et al, 2003).…”

Sorbitol Metabolism, the Climacteric, and Watercore in Apples

“…Although activities of ME generally increased there was no subsequent decrease until late in the season when activities dropped precipitously in the then senescent fruit. Despite other reports (13,16) of striking increases, e.g., 300%, in ME activity just prior to the climacteric in peel and pulp tissues of 'Cox's Orange Pippin,' our increases were less substantial and similar to those recently reported by Hartmann and colleagues (10) for excised pulp cylinders from 'Golden Delicious'.…”

“…This relationship was observed in both years of the study. It appeared here that SDH activities increase in association with the climacteric as do malic enzyme, pyruvate decarboxylase, and other enzyme activities (7,13,14,16). Although we do not have proof of de novo synthesis of SDH during the climacteric as is available for other pome fruit enzymes (9,14,15), our data indicate that the observed increases in SDH represent part of the complex of changes associated with the climacteric.…”

“…Although we do not have proof of de novo synthesis of SDH during the climacteric as is available for other pome fruit enzymes (9,14,15), our data indicate that the observed increases in SDH represent part of the complex of changes associated with the climacteric. Although SDH begins to increase prior to the onset of the climacteric, several tricarboxylic acid cycle enzymes also have been shown to reach peak activity several days before the respiratory peak is achieved (16). Also, aldose 6-phosphate reductase (sorbitol 6-phosphate dehydrogenase), another enzyme of sorbitol metabolism (21), increased in ethylene-treated loquat fruit (11).…”

Ripening and in Vitro Retention of Respiratory Control by Avocado and Pear Mitochondria

“…The absence, or near absence, of ultrastructural change in the mitochondria of ripening pear (1), apple (17), and tomato (9) fruits plus the persistent capacity of mitochondria to oxidize substrates and demonstrate respiratory control throughout the climacteric of many fruits, including avocado (10,14), tomato (8), apple (11)(12)(13), and banana (7) attest to the fact that mitochondria in senescing fruit cells remain functionally sound. Nonetheless, Romani et al (26) discerned a ripening, age-related change in the mitochondrial system based on the observation that mitochondria in climacteric pears can neither withstand nor recover from doses of ionizing radiation that are tolerated by mitochondria in preclimacteric fruit.…”