Functional uncoupling of the tonoplast proton pump and its effect on the flesh gelling physiological disorder in papaya fruit

Diagram representative of the primary active transport of the plasma membrane and tonoplast and its relation to the flesh gelling physiological disorder in papaya. In the scheme shown are the P-ATPase (1) and V-ATPase (2) and V-PPase (3), responsible for the pumping of protons (water green circles) into the apoplast and vacuole. The primary transport allows potassium ions (light gray circles) and sugar (purple circles) to enter into the cytoplasm and on the vacuole through the potassium channels (4) and sugar transporter (5), respectively. The larger arrows indicate the movement of water (two dark water green color circles and a dark gray color circle together) flow of the cell through the water channels according to the potential gradient generated from the smaller input ions and sugar to the vacuole. The water output from the vacuole and its accumulation in apoplast is the cause of soaked appearance of the mesocarp and higher presence of plasmolyzed cells are typical of papaya pulp with the physiological disorder. A H+ leakage is shown in tonoplast symbolizing the possible loss of vacuolar membrane permeability in papaya gelled.