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Study of glucose starvation in excised maize root tips
R Brouquisse1, F James, P Raymond
1Institut National de la Recherche Agronomique, Station de Physiologie Végétale, BP 81, 33883 Villenave d'Ornon Cedex, France.
Plant Physiology
|June 1, 1991
Summary
Glucose starvation in maize root tips causes respiration to decrease, with tissues dying after 200 hours. This suggests respiration is limited by biosynthesis, not mitochondria, and starvation becomes irreversible after 90 hours.
Area of Science:
- Plant Physiology
- Biochemistry
- Molecular Biology
Background:
- Excised maize (Zea mays) root tips are a model system for studying cellular responses to nutrient deprivation.
- Prolonged glucose starvation impacts fundamental metabolic processes in plant tissues.
Purpose of the Study:
- To investigate the effects of prolonged glucose starvation on respiration, substrate utilization, and metabolic enzyme activity in excised maize root tips.
- To determine the point of irreversible damage and potential causes during starvation.
Main Methods:
- Monitoring respiration rate, energy charge, and substrate content over 200 hours of starvation.
- Assessing the activity of enzymes involved in sugar metabolism and the Krebs cycle.
- Evaluating the reversibility of starvation effects and changes in cellular parameters.
Main Results:
- Respiration rate declined to 30-40% within 20 hours and tissues died after 200 hours.
- Sugar content depleted by 120 hours; proteins and lipids became primary respiratory substrates.
- Enzymic activities decreased significantly, and starvation became irreversible after 80-90 hours, coinciding with osmolarity loss and dry weight reduction.
Conclusions:
- Respiration in excised maize root tips is primarily limited by ATP-utilizing biosynthesis rates, not mitochondrial abundance.
- Irreversibility of starvation, similar to senescence, may stem from altered membrane selective permeability.