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Published on: March 30, 2018
Endosperm acidification and related metabolic changes in the developing barley grain
1Commonwealth Scientific and Industrial Research Organization, Division of Plant Industry, Canberra, A.C.T., Australia.
Plant Physiology
|March 1, 1992
Summary
Barley grain (Hordeum vulgare L.) acidifies during maturation due to malate accumulation, linked to changes in enzyme activity. This suggests a mixed metabolism in the aleurone layer during grain development.
Area of Science:
- Plant Physiology
- Biochemistry
- Agricultural Science
Background:
- Barley grain (Hordeum vulgare L.) undergoes significant physiological changes during maturation.
- Acidification of the starchy endosperm (SE) is a key event in barley grain development.
Purpose of the Study:
- To investigate the physiological and biochemical changes associated with barley grain acidification during maturation.
- To understand the role of enzyme activity and metabolic pathways in this process.
Main Methods:
- Monitoring pH, organic acid accumulation (malate, citrate, lactate), and enzyme activities (phosphoenolpyruvate carboxylase, alcohol dehydrogenase [ADH]) in barley grain.
- Analyzing changes in ADH isozymes and cellular respiration rates (adenylate energy charge [AEC]) in the pericarp/testa/aleurone (PTA) and SE.
Main Results:
- Grain pH decreases significantly during maturation, correlating with malate and lactate accumulation in the PTA.
- Increased activity of phosphoenolpyruvate carboxylase and ADH in the PTA, with changes in ADH isozymes in both PTA and SE.
- PTA maintained high respiration and AEC, while SE showed low respiration and rising AEC, indicating hypoxia in the SE.
Conclusions:
- The observed changes suggest the development of a malate/ethanol fermentation (mixed metabolism) in the aleurone layer during barley grain maturation.
- Hypoxia in the starchy endosperm likely plays a role in regulating these metabolic shifts.
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