The pore size of non-graminaceous plant cell walls is rapidly decreased by borate ester cross-linking of the pectic polysaccharide rhamnogalacturonan II
The walls of suspension-cultured Chenopodium album L. cells grown continually for more than 1 year on B-deficient medium contained monomeric rhamnogalacturonan (mRG-II) but not the borate ester cross-linked RG II dimer (dRG-II-B). The walls of these cells had an increased size limit for dextran permeation, which is a measure of wall pore size. Adding boric acid to growing B-deficient cells resulted in B binding to the wall, the formation of dRG-II-B from mRG-II, and a reduction in wall pore size within 10 min. The wall pore size of denatured B-grown cells was increased by treatment at pH {le} 2.0 or by treatment with Ca{sup 2+}-chelating agents. The acid-mediated increase in wall pore size was prevented by boric acid alone at pH 2.0 and by boric acid together with Ca{sup 2+}, but not by Na{sup +} or Mg{sup 2+} ions at pH 1.5. The Ca{sup 2+}-chelator-mediated increase in pore size was partially reduced by boric acid. Their results suggest that B-mediated cross-linking of RG-II in the walls of living plant cells generates a pectin network with a decreased size exclusion limit for polymers. The formation, stability, and possible functions of a borate ester cross-linked pectic network in the primary walls of nongraminaceous plant cells are discussed.
- Research Organization:
- Humboldt-Univ., Berlin (Germany); US Department of Energy, Washington, DC
- Sponsoring Organization:
- Deutsche Forschungsgemeinschaft DFG (German Research Partnership); US Department of Energy
- DOE Contract Number:
- FG02-96ER20220; FG05-93ER20097
- OSTI ID:
- 20006201
- Journal Information:
- Plant Physiology (Bethesda), Journal Name: Plant Physiology (Bethesda) Journal Issue: 3 Vol. 121; ISSN 0032-0889; ISSN PLPHAY
- Country of Publication:
- United States
- Language:
- English
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