title: Characterization of cell walls in bean (Phaseolus vulgaris L.) callus cultures tolerant to dichlobenil.
abstract: The increase in dry weight during the culture of bean callus cultures was inhibited by the herbicide dichlobenil (2,6-dicholorobenzonitrile) with an I(50) of 0.5 µM. However bean calli became tolerant to a concentration of 12 µM by a stepwise increase in the concentration of the inhibitor in each subculture. Tolerant calli growing in 2,6-dicholorobenzonitrile developed with hollow protuberances. Groups of cells in these protuberances had irregular cell walls surrounded by a thicker cell wall with a lamellate structure and without a differentiated middle lamella. FTIR spectra of tolerant cell walls revealed an increase in both esterified and non-esterified pectins. Cell wall fractionation showed that in tolerant cell walls the xyloglucan-cellulose network of non-tolerant cell walls was partly replaced by a pectin-rich network mainly formed of cross-linked polyuronides with a large proportion of homogalacturonan. These modifications are comparable to those described for bean calli tolerant to isoxaben, pointing to a related mechanism of tolerance for both herbicides.
authors.affiliation: Departamento de Biologìa Vegetal, Laboratorio de Fisiología Vegetal, Universidad de León, E-24071, León, Spain
authors.forename: A E.
authors.initials: AE
authors.lastname: Encina
authors.forename: R M.
authors.initials: RM
authors.lastname: Moral
authors.forename: J L.
authors.initials: JL
authors.lastname: Acebes
authors.forename: J M.
authors.initials: JM
authors.lastname: Álvarez