Cell wall alterations

To study the cell wall alterations diiring processing in detail, total pectic fractions were separated by extraction of AIR from fresh, blanched and sterilized beans with acetate buffer, CDTA and NajCOj. Analysis showed that sterilization caused a lai e increase in the amount of buffer soluble pectins (Figure 1). 

C. Cell Wall Alterations at the Plant-Fungus Interface... 

F. Paris, J. Dexheimer, and F. Lapeyric, Cytochemical evidence of a fungal cell wall alteration during infection of Eucalyptus roots by the ectomycon hizal fungus Cenococcum geophUum. Arch Microbiol. 159 526 (1993). 

Cell Wall Alterations and Antimicrobial Defense in Perennial Plants... 

Should the barrier presented by the secondary plant surface be breached, defence mechanisms may operate in the bark (i.e., secondary cortex and phloem) of woody plants, limiting pathogen development. These include chemical defences and structural barriers resulting from cell wall alterations... 

Both probably act in concert, although in a non-woody plant (carrot) it has been concluded that the importance of cell wall alterations was secondary to that of chemical defence (24). Only the cell wall alterations involved in defence will be considered further here. 

In some species, however, e.g. ash, Fraxinus excelsior, cells of the traumatic axial parenchyma of the compartmentalization wall 4 may show no evidence of cell wall alterations, yet appear to act normally as a functional barrier to decay (Pearce, R.B., unpublished data). It is to be presumed that the spread of decay fungi is arrested either by chemical defences or by environmental constraints (cf. 26-28) in such species. Clearly, a contribution may be made by these defences in suberizing species also phytoalexin-like antifungal compounds have been detected in association with a suberized wall 4 barrier in Acer saccharinum (42). More work will be required to elucidate the long-term effectiveness of the various mechanisms maintaining the function of these barrier walls. 

As defence mechanisms in plants commonly act in concert, it would be wrong to ascribe a primary role to these various wall alterations without additional investigation in virtually all cases evidence for the concomitant operation of chemical defences is also available. However, cell wall alterations are particularly well suited to long term defence, providing stable and durable barriers that are not dependant on the continuing metabolic activity of living cells to maintain them, and which are not subject to chemical instability or leaching. 

PEARCE Cell Wall Alterations Antimicrobial Defense... 

Mechanism of Action Atricyclicglycopeptide antibacterial that binds to bacterial cell walls, altering cell membrane permeability and inhibiting RNA synthesis. Therapeutic Effect Bactericidal. 

Aureal Cross I really cannot believe that the type of cell-wall alteration seen by Dr. Spackman in the Brandon lignite resulted from microbial attack. 

LPS also has effects on cell wall alterations such as callose deposition (Keshavarzi et al., 2004) and on PR gene induction (Zeidler et al., 2004 Silipo et al., 2005). In some cases specific effects of a particular LPS on plant gene induction are observed. LPS from the crucifer pathogen Xcc induced expression of a gene encoding a defense-related (->-(1 -3) glucanase when applied to turnip leaves at 1 p,g per ml. In contrast, LPS from Escherichia coli and Salmonella enterica were ineffective at concentrations up to 50 p,g per ml (Newman et al., 1995). Such specific effects may reflect the ability of particular plants to recognize structural features within LPS that are not widely conserved. 

RA Blanchette, EW Krueger, JE Haight, M Akhtar, DE Akin. Cell wall alterations in loblolly pine wood decayed by the white-rot fungus, Ceriporiopsis subvermispora. J Biotechnol 53 203-213, 1997. 

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