Species specificity of resistance to oxygen diffusion in thin cuticular membranes from amphibious plants

Cuticular membranes (CM) were isolated enzymatically from leaves of amphibious and submerged plants, and the oxygen permeability of aerial and aquatic CMs was compared using a specially constructed oxygen electrode. Their thicknesses were estimated from transmission electron micrographs of intact leaves. When dry CMs were moistened, the permeability of typical aerial CMs changed differently from that of typical aquatic CMs during the desiccation, apparently reflecting different internal structures. The cuticle thickness was mostly <100 nm, and the range of permeance values was 5-143 x 10(-6) m s(-1), corresponding to resistance values of 7-210 x 10(3) s m(-1) . The resistance of an aerial CM was always higher than that of an aquatic one from the same species. Only the aquatic CMs showed a weak proportionality between resistance and thickness. The relation between resistance and thickness varied from aquatic to aerial CMs in a species specific way.