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Increased Fatty Acid beta-Oxidation after Glucose Starvation in Maize Root Tips
M Dieuaide1, R Brouquisse, A Pradet
1Institut National de la Recherche Agronomique Centre de Recherche de Bordeaux Station de Physiologie Végétale, BP 81 33883 Villenave d'Ornon, Cedex, France.
Plant Physiology
|June 1, 1992
Summary
Glucose starvation significantly boosts fatty acid oxidation in maize roots, increasing beta-oxidation activity. This metabolic shift helps plants utilize lipids and proteins when carbohydrates are scarce, crucial for survival.
Area of Science:
- Plant Physiology
- Biochemistry
- Molecular Biology
Background:
- Plant root tips rely on carbohydrates for energy.
- Glucose starvation triggers metabolic adaptations in plants.
- Fatty acid oxidation is a key energy pathway.
Purpose of the Study:
- To investigate the impact of glucose starvation on fatty acid oxidation in maize root tips.
- To identify changes in key metabolic enzymes during starvation.
- To understand the role of beta-oxidation in plant response to nutrient deficiency.
Main Methods:
- Excised maize root tips were subjected to glucose starvation for 24 hours.
- Fatty acid oxidation rates were measured by monitoring CO(2) production from palmitic acid.
- Enzyme activities, including beta-oxidation enzymes, were quantified in crude particulate fractions.
- High-performance liquid chromatography (HPLC) was used to assay acetyl-CoA formation.
Main Results:
- Glucose starvation increased palmitic acid oxidation to CO(2) by 2.5-fold.
- Activities of beta-oxidation enzymes (crotonase, hydroxyacyl-CoA dehydrogenase, thiolase) and other enzymes (catalase, malate synthase, peroxisomal citrate synthase) were elevated post-starvation.
- Overall beta-oxidation activity, measured by [(14)C]acetyl-CoA formation, increased two- to fivefold in starved roots.
- No isocitrate lyase activity was detected, indicating the glyoxylate cycle is not operational.
Conclusions:
- Plant root beta-oxidation activity significantly increases under glucose starvation.
- This enhanced activity is a critical adaptation, allowing lipids and proteins to serve as primary respiratory substrates.
- The findings provide insights into metabolic adjustments in senescing plant tissues and response to nutrient stress.
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