3,7-dichloroquinolinecarboxylic acid inhibits cell-wall biosynthesis in maize roots

• Published in: Plant physiology (Bethesda) Vol. 112; no. 3; pp. 1383 - 1389
• Main Authors: Koo, S.J. (LG Chemical Limited Research Park, Taejon, Korea.), Neal, J.C, DiTomaso, J.M
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.11.1996
• Subjects: ACIDE GRAS; ACIDOS GRASOS; ADN; ANABOLISME; ANABOLISMO; ARN; Biochemistry and Enzymology; Biological and medical sciences; BIOSINTESIS; BIOSYNTHESE; Biosynthesis; Cell walls; CELLULE; CELULAS; Chemical control; Corn; CRECIMIENTO; CROISSANCE; DNA; DURACION; DUREE; Ethylene production; Fatty acids; Fundamental and applied biological sciences. Psychology; HERBICIDAS; HERBICIDE; Herbicides; Parasitic plants. Weeds; PARED CELULAR; PAROI CELLULAIRE; Phytopathology. Animal pests. Plant and forest protection; Plant roots; Plants; PLANTULAS; PLANTULE; RACINE; RAICES; RNA; Weeds; ZEA MAYS; Monocotyledones; Zea mays; Radiolabelling; Quinoline derivatives; Biosynthesis; Herbicide; Cereal crop; Cell wall; Gramineae; Angiospermae; Spermatophyta; Biosynthesis precursor; Mechanism of action; Comparative study
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.112.3.1383

The mode of action of the herbicide 3,7-dichloroquinolinecarboxylic acid (quinclorac) was examined by measuring incorporation of [14C]glucose, [14C]acetate, [3H]thymidine, and [3H]uridine into maize (Zea mays) root cell walls, fatty acids, DNA, and RNA, respectively. Among the precursors examined, 10 micromolar quinclorac inhibited [14C]glucose incorporation into the cell wall within 3 h. Fatty acid and DNA biosynthesis were subsequently inhibited, whereas RNA biosynthesis was unaffected. In contrast to the cellulose synthesis inhibitor 2,6-dichlorobenzonitrile, quinclorac strongly inhibited cellulose and a hemicellulose fraction presumed to be glucuronoarabinoxylan. However, the synthesis of (1 leads to 3),(1 leads to 4)-beta-D-glucans was only slightly inhibited. The degree of inhibition was time- and dose-dependent. By 4 h after treatment, the concentration that inhibited [14C]glucose incorporation into the cell wall, cellulose, and the sensitive hemicellulose fraction by 50% was about 15, 5, and 20 micromolar, respectively. Concomitant with an inhibition of [14C]glucose incorporation into the cell wall, quinclorac treatment led to a marked accumulation of radioactivity in the cytosol. The increased radioactivity was found mostly in glucose and fructose. However, total levels of glucose, fructose, and uridine diphosphate-glucose were not changed greatly by quinclorac. These data suggest that quinclorac acts primarily as a cell-wall biosynthesis inhibitor in a susceptible grass by a mechanism that is different from that of 2,6-dichlorobenzonitrile