On the role of the cell wall in the phenomenon of copper tolerance in Silene paradoxa L.

The potential role of the cell wall in the phenomenon of copper tolerance in Silene paradoxa was investigated. Plants from Fenice Capanne (FC, copper tolerant population) mine waste and Colle Val D'Elsa (CVD, sensitive population) uncontaminated soil were grown in hydroponics and exposed to different CuSO4 treatment to evaluate tolerance, accumulation and pectin concentration of the root cell wall. Physiological mechanisms relying both on avoidance and tolerance at the cellular level seemed to characterise the copper tolerance phenomenon showed by the metallicolous population of S. paradoxa. Avoidance was realised at both the symplast and the apoplast levels in the roots. Data suggested that in the tolerant population the presence of copper in the culture medium could decrease root cell wall pectin concentration and increase pectin methylation degree. Results proposed that a low cell wall ability to bind copper can probably combine to generate the tolerant/excluder phenotype of the S. paradoxa copper tolerant population.