Both foliar and residual applications of herbicides that inhibit amino acid biosynthesis induce alternative respiration and aerobic fermentation in pea roots

• Published in: Plant biology (Stuttgart, Germany) Germany), 2016-05, Vol.18 (3), p.382-390
• Main Authors: Armendáriz, O., Gil-Monreal, M., Zulet, A., Zabalza, A., Royuela, M.
• Format: Article
• Language: English
• Subjects: 5-Enolpyruvylshikimate-3-phosphate synthase; Accumulation; acetolactate synthase inhibitor; Aerobic conditions; Alternative oxidase; alternative respiratory pathway; Amino acids; Amino Acids - biosynthesis; Biosynthesis; Carbohydrate metabolism; Carbohydrates; Carbon; Cell Respiration - drug effects; Chain branching; Cytochrome; Ethanol; Fermentation; Fermentation - drug effects; Glycine - analogs & derivatives; Glycine - pharmacology; Glyphosate; Herbicides; Herbicides - pharmacology; imazamox; Imidazoles - pharmacology; imidazolinone; Inhibitors; Leaves; Metabolism; Metabolites; Mitochondrial Proteins - metabolism; Oxidoreductases - metabolism; Pisum sativum - drug effects; Pisum sativum - enzymology; Pisum sativum - physiology; Plant Leaves - drug effects; Plant Leaves - enzymology; Plant Leaves - physiology; Plant Proteins - metabolism; Plant Roots - drug effects; Plant Roots - enzymology; Plant Roots - physiology; Plants (botany); Pyruvic acid; Respiration; Roots; Sugar
• ISSN: 1435-8603; 1438-8677
• DOI: 10.1111/plb.12412

The objective of this work was to ascertain whether there is a general pattern of carbon allocation and utilisation in plants following herbicide supply, independent of the site of application: sprayed on leaves or supplied to nutrient solution. The herbicides studied were the amino acid biosynthesis-inhibiting herbicides (ABIH): glyphosate, an inhibitor of aromatic amino acid biosynthesis, and imazamox, an inhibitor of branched-chain amino acid biosynthesis. All treated plants showed impaired carbon metabolism; carbohydrate accumulation was detected in both leaves and roots of the treated plants. The accumulation in roots was due to lack of use of available sugars as growth was arrested, which elicited soluble carbohydrate accumulation in the leaves due to a decrease in sink strength. Under aerobic conditions, ethanol fermentative metabolism was enhanced in roots of the treated plants. This fermentative response was not related to a change in total respiration rates or cytochrome respiratory capacity, but an increase in alternative oxidase capacity was detected. Pyruvate accumulation was detected after most of the herbicide treatments. These results demonstrate that both ABIH induce the less-efficient, ATP-producing pathways, namely fermentation and alternative respiration, by increasing the key metabolite, pyruvate. The plant response was similar not only for the two ABIH but also after foliar or residual application.