Oxaziclomefone, a new herbicide, inhibits wall expansion in maize cell-cultures without affecting polysaccharide biosynthesis, xyloglucan transglycosylation, peroxidase action or apoplastic ascorbate oxidation.
OBJECTIVE
Oxaziclomefone (OAC), a new herbicide, inhibits cell expansion, especially in roots and cell-cultures of gramineous monocots. OAC does not affect turgor in cultured maize cells, and must therefore inhibit wall-loosening or promote wall-tightening.


METHODS
The effects of OAC in living cultured maize cells on various biochemical processes thought to influence wall extension were studied.


RESULTS
OAC did not affect 14C-incorporation from D-[U-14C]glucose into the major sugar residues of the cell wall (cellulosic glucose, non-cellulosic glucose, arabinose, xylose, galactose, mannose or uronic acids). OAC had no effect on 14C-incorporation from trans-[U-14C]cinnamate into wall-bound ferulate or its oxidative coupling-products. OAC did not influence the secretion or in-vivo action of peroxidase or xyloglucan endotransglucosylase activities-proposed wall-tightening and -loosening activities, respectively. The herbicide did not affect the consumption of extracellular L-ascorbate, an apoplastic solute proposed to act as an antioxidant and/or to generate wall-loosening hydroxyl radicals.


CONCLUSIONS
OAC decreased wall extensibility without influencing the synthesis or post-synthetic modification of major architectural wall components, or the redox environment of the apoplast. The possible value of OAC as a probe to explore aspects of primary cell wall physiology is discussed.
O'Looney
Nichola
N
The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, School of Biological Sciences, The University of Edinburgh, Daniel Rutherford Building, The King's Buildings, Mayfield Road, Edinburgh EH9 3JH, UK.
Fry
Stephen C
SC
D001205:Ascorbic Acid / Q000378:metabolism*; D049108:Cell Enlargement / Q000187:drug effects; D002473:Cell Wall / Q000187:drug effects*; D002478:Cells, Cultured; D002934:Cinnamates / Q000378:metabolism; D005936:Glucans / Q000378:metabolism*; D006031:Glycosylation; D016695:Glycosyltransferases / Q000378:metabolism; D006540:Herbicides / Q000737:chemistry / Q000494:pharmacology; D015394:Molecular Structure; D010078:Oxazines / Q000737:chemistry / Q000494:pharmacology*; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000378:metabolism*; D011134:Polysaccharides / Q000096:biosynthesis*; D013997:Time Factors; D014990:Xylans / Q000378:metabolism*; D003313:Zea mays / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology
D002934:Cinnamates; D005936:Glucans; D006540:Herbicides; D010078:Oxazines; D011134:Polysaccharides; D014990:Xylans; C029353:xyloglucan; C507381:oxaziclomefone; D009195:Peroxidase; D016695:Glycosyltransferases; C473049:xyloglucan - xyloglucosyltransferase; D001205:Ascorbic Acid