AOBPreview originally published online on April 12, 2008
Annals of Botany 2008 101(9):1329-1339; doi:10.1093/aob/mcn051
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Habituation of Bean (Phaseolus vulgaris) Cell Cultures to Quinclorac and Analysis of the Subsequent Cell Wall Modifications
Departamento de Ingeniería y Ciencias Agrarias, Área de Fisiología Vegetal, Universidad de León, E-24071, León, Spain
* For correspondence. E-mail jl.acebes{at}unileon.es
Received: 3 January 2008 Returned for revision: 19 February 2008 Accepted: 7 March 2008 Published electronically: 12 April 2008
Background and Aims: The herbicide quinclorac has been reported to inhibit incorporation of glucose both into cellulose and other cell wall polysaccharides. However, further work has failed to detect any apparent effect of this herbicide on the synthesis of the wall. In order to elucidate whether quinclorac elicits the inhibition of cellulose biosynthesis directly, in this study bean cell calli were habituated to grow on lethal concentrations of the herbicide and the modifications in cell wall composition due to the habituation process were analysed.
Methods: Fourier transform infrared spectroscopy associated with multivariate analysis, cell wall fractionation techniques, biochemical analyses and the immunolocation of different cell wall components with specific monoclonal antibodies were used to characterize the cell walls of quinclorac-habituated cells.
Key Results: Quinclorac-habituated cells were more irregularly shaped than non-habituated cells and they accumulated an extracellular material, which was more abundant as the level of habituation rose. Habituated cells did not show any decrease in cellulose content, but cell wall fractionation revealed that changes occurred in the distribution and post-depositional modifications of homogalacturonan and rhamnogalacturonan I during the habituation process. Therefore, since the action of quinclorac on the cell wall does not seem to be due to a direct inhibition of any cell wall component, it is suggested that the effect of quinclorac on the cell wall could be due to a side-effect of the herbicide.
Conclusions: Long-term modifications of the cell wall caused by the habituation of bean cell cultures to quinclorac did not resemble those of bean cells habituated to the well-known cellulose biosynthesis inhibitors dichlobenil or isoxaben. Quinclorac does not seem to act primarily as an inhibitor of cellulose biosynthesis.
Key words: Quinclorac, herbicide, Phaseolus vulgaris, cell culture habituation, primary cell wall, cellulose, FTIR spectroscopy
Present address: Department of Molecular Biology, Københavns Biocenter, Københavns Universitet, Ole Maaløes Vej 5, 2200 København N, Denmark.