Metal-tolerant moss Scopelophila cataractae accumulates copper in the cell wall pectin of the protonema.

The growth kinetics in the presence of copper (Cu) of the protonema of the moss Scopelophila cataractae and the matrix polysaccharides of its cell walls have been analyzed in this study. Protonemal cells cultured in a medium containing 0.2mM CuSO(4) showed a rapid accumulation of Cu, reaching a maximum between 30 and 60d at approximately 65 micromolg(-1) DW. Uronic acids were found in similar amounts in cell walls of both control and Cu-treated cells, whereas arabinose and galactose decreased to 61-67% in the presence of Cu. Cell wall polysaccharides were determined after successive extraction with 50mM CDTA, 50mM Na(2)CO(3), 1M KOH, and 4M KOH. The pectic fractions (CDTA- and Na(2)CO(3)-soluble) decreased to 47% and the hemicellulosic fractions (1M KOH- and 4M KOH-soluble) to 86% under Cu application. Approximately 43% of the Cu taken into cell walls was released following endo-pectate lyase treatment, suggesting that two-fifths of the total Cu accumulation was tightly bound to the homogalacturonan of the cell wall pectin. Copyright 2009 Elsevier GmbH. All rights reserved.