Abstract
When frozen flower buds of apple trees started to thaw, an abrupt decrease of levels of reduced glutathione and glucose-6-phosphate occurred, even without freezing injuries. With freezing injuries, a steep decrease in the levels of the above substrates was observed, suggesting that the level of generating peroxide depends on freezing temperatures. Enzyme systems involved in the regeneration of reduced glutathione also do not seem to function properly in poplar twigs in a frozen milieu. At about - 10°C, a decrease in levels of reduced glutathione was detected and this decrease was followed by a decrease in levels of glucose 6-phosphate. When twigs that contained depressed levels of reduced glutathione and glucose-6-phosphate were transferred to 4°C, overcompensation for the decrease in reduced glutathione and glucose-6-phosphate occurred and the resultant surplus appeared to reflect the metabolic dysfunction in the supply and demand for reduced glutathione and glucose-6-phosphate that occurs under frozen conditions. These results suggest that the sequence of reactions which starts from the reaction catalyzed by hexokinase, through reactions catalyzed by glucose-6-phosphate dehydrogenase and glutathione reductase, does not function properly under frozen conditions in perennial plants.
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Claims 6
Claim · model-written summary
Thawing frozen apple flower buds abruptly decreased reduced glutathione and glucose-6-phosphate even without injury.
- Taxon
- apple trees
Malus domesticae0 - Organ / stage
- flower budse0
- Treatment
- started to thawe0
- Outcome
- levels of reduced glutathione and glucose-6-phosphatee0
- Direction
- decreasee0
- Qualifier
- even without freezing injuriese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When frozen flower buds of apple trees started to thaw, an abrupt decrease of levels of reduced glutathione and glucose-6-phosphate occurred, even without freezing injuries”
Claim · model-written summary
Freezing injury was accompanied by a steep decrease in those substrates.
- Taxon
- apple treesMalus domesticat0
- Treatment
- freezing injuriese0
- Outcome
- levels of the above substratese0
- Direction
- decreasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With freezing injuries, a steep decrease in the levels of the above substrates was observed”
t0“frozen flower buds of apple trees started to thaw”
Claim · model-written summary
At about - 10°C poplar twigs lost reduced glutathione.
Verbatim
e0“At about - 10°C, a decrease in levels of reduced glutathione was detected”
t0“poplar twigs in a frozen milieu”
Claim · model-written summary
The glutathione decrease was followed by a glucose 6-phosphate decrease in poplar.
Verbatim
e0“this decrease was followed by a decrease in levels of glucose 6-phosphate”
t0“poplar twigs in a frozen milieu”
Claim · model-written summary
Transfer to 4°C produced overcompensation of reduced glutathione and glucose-6-phosphate in poplar twigs.
Verbatim
e0“When twigs that contained depressed levels of reduced glutathione and glucose-6-phosphate were transferred to 4°C, overcompensation for the decrease in reduced glutathione and glucose-6-phosphate occurred”
t0“poplar twigs in a frozen milieu”
Claim · model-written summary
The authors infer that the hexokinase to glutathione reductase reaction sequence malfunctions when frozen.
Verbatim
e0“the sequence of reactions which starts from the reaction catalyzed by hexokinase, through reactions catalyzed by glucose-6-phosphate dehydrogenase and glutathione reductase, does not function properly under frozen conditions in perennial plants”