Does Cd possess the stimulatory effect on gas exchange and photochemistry in C3-CAM intermediate plants?

Abstract The soil-grown semi-halophytic CAM (crassulacean acid metabolism) facultative model plant - Mesembryanthemum crystallinum L. (common ice plant) exhibits minute toxicity symptoms when exposed to elevated cadmium doses. In this study, photochemical activity as well as gas exchange of the soil-grown C3-CAM- performing plants to increased cadmium concentrations (0.01-10.0 mM) were investigated. An increase of net photosynthesis (PN) observed in C3- performing plants upon exposure to Cd runs in parallel with the rise of transpiration level. As the transpiration process tends to be elevated also in darkness, it gives rise to the suggestion that the first effect of Cd presence is stimulation of stomata aperture. Also, photochemical activity is well-secured in Cd-treated plants, which implies the involvement of additional mechanisms triggered to protect M. crystallinum against Cd toxicity.