The cell wall stiffening mechanism in Pinus pinaster Aiton:: regulation by apoplastic levels of ascorbate and hydrogen peroxide

The peroxidase activity associated with cell walls from hypocotyls of Pinus pinaster Aiton seedlings grown in the absence of light as well as cell wall content of ferulic acid, cell wall extensibility and apoplastic ascorbate and hydrogen peroxide contents are reviewed in relation to the cell wall stiffening mechanism and growth cessation. Phenolic cross-linking, mainly 8,8'-dehydrodiferulate, between wail polysaccharides formed by the action of wall peroxidase is the main factor involved in the wall stiffening mechanism, A regulatory mechanism for stiffening based on the relative content of ascorbate and hydrogen peroxide in the apoplast is proposed. (C) 1999 Society of Chemical Industry.