Cell wall pectins : from immunochemical characterization to biological activity: Cell wall pectins : from immunochemical characterization to biological activity

The plant cell wall contacts lligll and low affinity sites for the adsorption of bivalent cations. 111g)1 affinity sites constante a signifiant amount of the constitutive homopolygalacturonic acide (PGA). Monoclonal antibodies bave been raised to PGA and they recognize oligomers with regrets of polymerization (DP)>ou = 9 under a calcium-induced conformation. Immunocytochemistry indicates the prescence of this acidic pectin at cell corners mainly, unless deesterification of the primary wall. The same pectic fragments with DP> ou = 9 trigger the activation of defense mechanisms in plant cells by a signal transduction pathway involving calcium and phosphoinositides. The binding of fragments by the antinomies surpresses the response, which means thay the epitope recognized by the antipody is part of the pectic signal perceived by plant cells.