ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

The effect of hypoxia on the control of carbohydrate metabolism in ripening bananas.

Hill, S. A.; Rees, T. ap;

Planta Year: 1995 Vol: 197 Issue: 2 Pages: 313-323 Ref: 42 ref.

1995

บทคัดย่อ

In a study on the effects of hypoxia on the major fluxes of carbohydrate metabolism in climacteric bananas (Musa cavendishii), hands of bananas, not ethylene-treated, were allowed to ripen in air at 21 deg C in the dark. When the climacteric began, fruits were transferred to 15 or 10% oxygen and were analysed once the climacteric peak had been reached 8-12 h later. The rates of starch breakdown, sucrose, glucose and fructose accumulation, and CO2 production were determined, as were the contents of hexose monophosphates, adenylates and pyruvate. In addition, the detailed distribution of label was determined after supplying [U-14C]-, [1-14C]-, [3,4-14C]- and [6-14C]glucose, and [U-14C]glycerol to cores of tissue under hypoxia. The data were used to estimate the major fluxes of carbohydrate metabolism. There was a reduction in the rate of respiration. The ATP:ADP ratio was unaffected but there was a significant increase in the content of AMP. In 15% oxygen, only minor changes in fluxes were observe

d. In 10% oxygen, starch breakdown was reduced and starch synthesis was not detected. The rate of sucrose synthesis decreased, as did the rate of re-entry of hexose sugars into the hexose monophosphate pool. There was a large increase in both the glycolytic flux and in the flux from triose phosphates to hexose monophosphates. It is argued that the increase in these fluxes is due to activation of pyrophosphate:fructose-6-phosphate 1-phosphotransferase, and that this enzyme has an important role in hypoxia.