Rapid Deposition of Extensin during the Elicitation of Grapevine Callus Cultures Is Specifically Catalyzed by a 40-Kilodalton Peroxidase

Abstract

Elicitation or peroxide stimulation of grape (Vitis vinifera L. cv Touriga) vine callus cultures results in the rapid and selective in situ insolubilization of an abundant and ionically bound cell wall protein-denominated GvP1. Surface-enhanced laser desorption/ionization/time of flight-mass spectrometry analysis, the amino acid composition, and the N-terminal sequence of purified GvP1 identified it as an 89.9-kD extensin. Analysis of cell walls following the in situ insolubilization of GvP1 indicates large and specific increases in the major amino acids of GvP1 as compared with the amino acids present in salt-eluted cell walls. We calculate that following deposition, covalently bound GvP1 contributes up to 4% to 5% of the cell wall dry weight. The deposition of GvP1 in situ requires peroxide and endogenous peroxidase activity. Isoelectric focusing of saline eluates of callus revealed only a few basic peroxidases that were all isolated or purified to electrophoretic homogeneity. In vitro and in situ assays of extensin cross-linking activity using GvP1 and peroxidases showed that a 40-kD peroxidase cross-linked GvP1 within minutes, whereas other grapevine peroxidases had no significant activity with GvP1. Internal peptide sequences indicated this extensin peroxidase (EP) is a member of the class III peroxidases. We conclude that we have identified and purified an EP from grapevine callus that is responsible for the catalysis of GvP1 deposition in situ during elicitation. Our results suggest that GvP1 and this EP play an important combined role in grapevine cell wall defense.

Genome-Wide Identification of Genes Expressed in Arabidopsis Pistils Specifically along the Path of Pollen Tube Growth

“…For example, cell walllocalized peroxidases can cause an increase in wall extensibility by generating hydroxyl radicals that degrade cell wall polysaccharides (Schopfer, 2001) or they can increase wall rigidity by mediating rapid cross-linking (insolubilization) of the structural cell wall Pro-rich extensins, as occurs upon physical damage, treatment with fungal elicitors, and pathogen infection (Bradley et al, 1992;Brownleader et al, 2000;Jackson et al, 2001). The presence of stigma surface peroxidases has been used as an indication of stigma receptivity for pollination in several species (e.g.…”

Peroxidases have more functions than a Swiss army knife

“…Peroxidases devoted to extensin cross-linking have been isolated from a large variety of plant species (Schnabelrauch et al 1996;Magliano and Casal 1998;Jackson et al 2001); they are known to act on the phenolic moiety of tyrosine, and maybe also on lysines, hence creating Tyr-Tyr or Tyr-Lys bonds (Schnabelrauch et al 1996). Tyrosines and lysines are evenly spaced on extensins within conserved motifs, hence contributing to the formation of a very uniform mesh within the cell wall structure (Kieliszewski and Lamport 1994).…”

A Biochemical and Molecular Characterization of LEP1, an Extensin Peroxidase from Lupin

“…Several studies have demonstrated that the capacity to efficiently cross-link extensin is not a property of class III peroxidases in general but is limited to particular peroxidases, referred to as extensin peroxidases (EPs) (8,(23)(24)(25)(26)(27). Although these peroxidases may be capable of oxidizing other phenolic substrates in vitro (24), it seems reasonable to assume that EPs, rather than other class III peroxidases, are responsible for the catalysis of essential extensin deposition in vivo.…”

“…Only a few EPs have been purified to date (8,24,27), and they remain to be characterized in depth. In previous work we described LEP1, an EP in lupin which is associated with white light inhibition of etiolated hypocotyl growth (8).…”