Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 1, 1995
Publication Date: N/A
Interpretive Summary: Low oxygen atmosphere has been shown to be desirable for maintaining quality of fresh produce. However, at the threshold level of extinction point, the point at which respiration is changing from aerobic to anaerobic, the enzymes responsible for the change is not clearly understood. This study showed that the enzyme PPi-phosphofructokinase, which has not been studied extensively in the past, appeared to regulate the glycolytic rate at the low oxygen level. This information is useful in better understanding the potential beneficial or deleterious effects of very low oxygen atmosphere.
Carrot (Daucus carota L.) shreds were stored under a continuous flow of 0.5 percent and 2 percent O2 (balance N2), or air for 9 days at 5 and 15C, and the resulting changes in respiration, levels of the glycolytic intermediates, and activities of ATP:phosphofructokinase (ATP-PFK) and PPi:phosphofructokinase (PPi-PFK) were monitored. Carrots under low O2 atmosphere exhibited an increase in RQ due to greater reduction in O2 consumption than CO2 production, and the increase in RQ was greater at 0.5 percent O2 than at 2 percent O2 atmosphere at both temperatures. Fructose 1,6-bisphosphate (F1,6P) accumulated with decreased O2 atmosphere and was two-fold greater at 0.5 percent O2 than at 2 percent O2 atmosphere at both temperatures. The levels of other glycolytic intermediates were not significantly influenced by the low O2. The changes in PPi-PFK activity occurred at the same time course as the F1, 6P accumulation. Similar correlation was not found with ATP-PFK. These results suggest that PPi-PFK may be involved in regulation of glycolysis under low O2 atmosphere.