Submitted to: American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 1, 1995
Publication Date: N/A
Interpretive Summary: Low oxygen atmosphere is desirable for maintaining the quality of fresh-cut fruits and vegetables; however, when the oxygen level is too low, anaerobic respiration is induced and results in injury to the product. An understanding of the enzymes or the reactions that triggers the anaerobic respiration will be helpful in selecting the minimal acceptable oxygen level for different commodities under various storage conditions; thus, a study was undertaken to determine the chemical components in carrots that may be associated with an enzyme that is affected by low oxygen. Results indicated that the necessary components were present to activate the enzyme PPi:phosphofructokinase that favors anaerobic respiration. This information will be useful to scientists who are undertaking research to better understand the physiology and biochemistry of plants as affected by controlled or modified atmosphere.
Fructose 2,6-bisphosphate (Fru-2,6-P2), through activation of pyrophosphate-dependent:phosphofructokinase (PPi-PFK) to glycoltyic direction, makes a major contribution to the control of flux between fructose 6-phosphate and fructose 1,6-bisphosphate (Fru-1,6-P2). This study was undertaken to determine the effect of low O2 atmosphere on the concentration of Fru-2,6-P2 and to determine if Fru-2,6-P2 was involved in the accumulation of Fru-1,6-P2. Results indicated that Fru-2,6-P2 remained unchanged in carrot root shreds (Daucus carota L.) held in air, but it increased 3.0- and 5.3-fold at 2 percent and 0.5 percent O2 atmpsphere, respectively, at 5C, and the increase was almost twice as much at 15C. The concentration of PPi ranged from 17 to 33 nmol.g-1 fresh weight. which was 35-40 percent of the size of ATP pool. With this adequate level of PPi and increase level of Fru-2,6-P2, PPi-PFK may be induced to favor the reaction toward glycolysis under the low O2 atmosphere.