title: Fermentative metabolism is induced by inhibiting different enzymes of the branched-chain amino acid biosynthesis pathway in pea plants.
abstract: The inhibition of branched-chain amino acid (BCAA) biosynthesis was evaluated in pea plants in relation to the ability for induction of fermentative metabolism under aerobic conditions. Chlorsulfuron and imazethapyr (inhibitors of acetolactate synthase, ALS, EC 4.1.3.18) produced a strong induction of pyruvate decarboxylase (PDC, EC 4.1.1.1) and alcohol dehydrogenase (ADH, EC 1.1.1.1) activities and a lesser induction of lactate dehydrogenase (LDH, EC 1.1.1.27) and alanine aminotransferase (AlaAT, EC 2.6.1.2) activities in roots. Inhibition of the second enzyme of the BCAA biosynthesis (ketol-acid reductoisomerase, KARI, EC 1.1.1.86) by Hoe 704 (2-dimethylphosphinoyl-2-hydroxyacetic acid) and CPCA (1,1-cyclopropanedicarboxylic acid) enhanced fermentative enzyme activities including PDC, ADH, and AlaAT. Fermentative metabolism induction occurring with ALS- and KARI-inhibitors was related to a higher expression of PDC. In the case of KARI inhibition, it is proposed that fermentation induction is due to an inhibition of ALS activity resulted from an increase in acetolactate concentration. Fermentative metabolism induction in roots, or at least ethanolic fermentation, appeared to be a general physiological response to the BCAA biosynthesis inhibition.
authors.affiliation: Departamento Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadia, Pamplona, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Zabalza
authors.forename: Esther M
authors.initials: EM
authors.lastname: González
authors.forename: Cesar
authors.initials: C
authors.lastname: Arrese-Igor
authors.forename: Mercedes
authors.initials: M
authors.lastname: Royuela
mesh_terms: D000095:Acetolactate Synthase / Q000037:antagonists & inhibitors; D000429:Alcohol Oxidoreductases / Q000037:antagonists & inhibitors; D000597:Amino Acids, Branched-Chain / Q000096:biosynthesis*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005285:Fermentation / Q000187:drug effects*; D050540:Ketol-Acid Reductoisomerase; D018532:Pisum sativum / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology / Q000378:metabolism
chemical_list: D000597:Amino Acids, Branched-Chain; D004791:Enzyme Inhibitors; D000429:Alcohol Oxidoreductases; D050540:Ketol-Acid Reductoisomerase; D000095:Acetolactate Synthase