Ion Relations of Apple Fruit Tissue During Fruit Development and Ripening. II. Phosphate Uptake

Abstract

Phosphate uptake by discs of cortical tissue from apple fruit was followed during fruit development and ripening. Uptake from 10^-3 M phosphate could be separated into a rapid, free-space uptake phase, followed by a plateau in the uptake rate, and then an increase in rate which was under metabolic control. During fruit development, the metabolic component of phosphate uptake underwent the greatest change. Apple fruit tissue exhibited an aging response in phosphate uptake. Accelerated uptake was found after 6 h aging and, after 20 h aging, the rate of phosphate uptake by the tissue was greatly enhanced. Aged tissue incorporated ³²P into the ester fraction within 1 h, in contrast to fresh tissue where incorporation in 1 h was negligible.