IONIC EFFECTS ON LIGNIFICATION AND PEROXIDASE IN TISSUE CULTURES

Area of Science:

• Plant biochemistry
• Cell biology
• Biophysics

Background:

• Crown gall tumor tissues release peroxidase into the medium.
• Peroxidase release is influenced by specific ion concentrations.
• This release is not attributed to diffusion from damaged cells.

Purpose of the Study:

• To investigate the role of specific ions in controlling peroxidase release from plant cell cultures.
• To understand the mechanism of ion-mediated enzyme release and its localization.
• To establish a link between ion concentration, peroxidase levels, and lignin deposition.

Main Methods:

• Utilized crown gall tumor tissue cultures.
• Measured peroxidase release into the culture medium.
• Performed cytochemical localization of peroxidase on cell walls and cytoplasm.
• Isolated and washed cell wall fractions to assess bound peroxidase.
• Treated cell wall fractions with divalent cations and ammonium to release bound enzyme.

Main Results:

• Calcium, magnesium, and ammonium ions significantly increased peroxidase release, in that order.
• Peroxidase was localized on cell walls and within the cytoplasm.
• Washed cell wall fractions retained bound peroxidase.
• Divalent cations (Ca(++), Sr(++), Ba(++)) and ammonium (NH(4)(+)) released bound peroxidase from cell walls, with specific effectiveness orders.
• Ion-induced peroxidase release from cell walls was demonstrated.

Conclusions:

• Specific ions directly control peroxidase release from plant cell walls.
• Ion-mediated peroxidase release affects enzyme levels on cell walls.
• This mechanism provides a basis for understanding how ions regulate lignin deposition in plant cell walls.