Phosphorylation in Avocado Fruit Slices in Relation to the Respiratory Climacteric

The rate of uptake of inorganic phosphate by tissue discs from both preclimacteric and climacteric peak avocados is linear for at least 60 minutes. The loss of (32)P upon excessive washing was much greater from peak than from preclimacteric tissue. Short incubation periods and, most important, rapid washing procedures are essential for meaningful comparisons.Phosphate esterification proceeded at a much greater rate in climacteric than in preclimacteric tissue. The phosphorylation was sensitive to 2,4-dinitrophenol (DNP). The ADP to ATP ratio decreased materially with the advance of ripening. It was concluded that neither uncoupling nor acceptor control can account for the onset of the respiratory rise. Changes in permeability appear to play an important role in fruit metabolism during the climacteric.