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

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.

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Ion Relations of Apple Fruit Tissue During Fruit Development and Ripening. III. Calcium Uptake

Functional Plant Biology ◽

10.1071/pp9810259 ◽

1981 ◽

Vol 8 (3) ◽

pp. 259 ◽

Cited By ~ 11

Author(s):

IB Ferguson ◽

CB Watkins

Keyword(s):

Fruit Development ◽

Free Space ◽

Calcium Uptake ◽

Apple Fruit ◽

Cortical Tissue ◽

Metabolic Component ◽

Fruit Development And Ripening ◽

Ion Relations ◽

Calcium Loss ◽

Extracellular Environment

The ability of discs of apple cortical tissue to take up calcium from salt solutions declined during fruit development. This was true for both the cellular and free-space components of uptake. The extent of reduction was greatest in the slow, linear phase of uptake, which in young fruit had a metabolic component inhibited at 4°C. Free-space uptake contributed some 80% of the total uptake capacity and dominated calcium loss in wash-out experiments. The magnitude of calcium uptake was reduced in the presence of 10-3 M magnesium but not by equivalent concentrations of potassium. Because of the low rate of calcium uptake into the cytoplasm and vacuole, we suggest that the greatest effect of calcium treatments used to control disorders such as bitter pit is to change the extracellular environment.

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Ion Relations of Apple Fruit Tissue During Fruit Development and Ripening. I. Cation Leakage

Functional Plant Biology ◽

10.1071/pp9810155 ◽

1981 ◽

Vol 8 (2) ◽

pp. 155 ◽

Cited By ~ 7

Author(s):

IB Ferguson ◽

CB Watkins

Keyword(s):

Fruit Development ◽

Tissue Concentration ◽

Apple Fruit ◽

Divalent Ions ◽

Fruit Tissue ◽

Fruit Development And Ripening ◽

Ion Relations ◽

Calcium Magnesium ◽

Calcium And Magnesium ◽

Potassium Leakage

Leakage of calcium, magnesium and potassium from discs of cortical apple fruit tissue was followed through fruit development and ripening. Leakage of potassium always exceeded that of calcium and magnesium and was little affected by the external presence of the divalent ions. Calcium and magnesium leakage was markedly increased by the external presence of either ion. In tissue from both freshly picked fruit and that taken from storage, potassium and magnesium leakage increased when the fruit was in an advanced state of senescence, but calcium leakage decreased. During fruit development, leakage of all cations was closely related to availability as expressed in tissue concentration. There was a marked increase in potassium leakage in association with the respiratory climacteric.

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