Spectral properties of the Cu-hyperaccumulating moss Scopelophila cataractae

To determine the characteristics of a Cu-hyperaccumulating moss Scopelophila cataractae and the influence of Cu on its structure and on chlorophyll (Chl), we measured reflectance and fluorescence (FL) spectra of S. cataractae samples with different Cu concentrations before and after wetting and the absorption spectra of Chl extracted from these samples. We found relationships between the spectral properties and Cu concentration. These relationships can be explained as follows. The higher the Cu concentration is, the lower is the plasticity of the cell wall, and the smaller is the increase in illuminated area due to the opening of the leaves after wetting. This results in a smaller increase in absorption and smaller decrease in reabsorption of the FL by Chl itself, and accordingly, a smaller increase in the FL band of Chl after wetting. Moreover, we found that the Chl concentration in S. cataractae is much higher than that in other common mosses and is correlated with an increase in the FL band of Chl after wetting. The remarkable increase in FL seen in S. cataractae and the slight increase in FL observed in other common mosses after wetting can be explained based on these findings.