Hydrogen peroxide-mediated cell-wall stiffening in vitro in maize coleoptiles

✍ Scribed by P. Schopfer

• Book ID: 104659388
• Publisher: Springer-Verlag
• Year: 1996
• Tongue: English
• Weight: 690 KB
• Volume: 199
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00196879

✦ Synopsis

It has recently been proposed that H202dependent peroxidative formation of phenolic cross-links between cell-wall polymers serves as a mechanism for fixing the viscoelastically extended wall structure and thus confers irreversibility to wall extension during cell growth (M. Hohl et al. 1995, Physiol. Plant. 94: 491-498). In the present paper the isolated cell wall (operationally, frozen/thawed maize coleoptile segments) was used as an experimental system to investigate H202-dependent cell-wall stiffening in vitro. Hydrogen peroxide inhibited elongation growth (in vivo) and decreased cell-wall extensibility (in vitro) in the concentration range of 10-10000 gmol-1-1. In rheological measurements with a constant-load extensiometer the stiffening effect of H202 could be observed with both relaxed and stressed cell walls. In-vitro cell-wall stiffening was a time-dependent reaction that lasted about 60 rain in the presence of saturating concentrations of H202. The presence of peroxidase in the growth-limiting outer epidermal wall of the coleoptile was shown by histochemical assays. Peroxidase inhibitors (azide, ascorbate) suppressed the wall-stiffening reaction by H202 in vitro. Hydrogen peroxide induced the accumulation of a fluorescent, insoluble material in the cell walls of living coleoptile segments. These results demonstrate that primary cell walls of a growing plant organ contain all ingredients for the mechanical fortification of the wall structure by H202-inducible phenolic cross-linking.