We investigated how the presence of cadmium (Cd) at the emergence of Phragmites australis (Cav.) Trin. ex Steudel plants from rhizomes interacted with leaf and chloroplast physiological and biochemical processes. About 8.5 nmol Cd per mg of chlorophyll were found in leaves, and 0.83 nmol Cd per mg of chlorophyll in chloroplasts, of plants treated with 50 µM Cd. As a result, a 30% loss of chlorophyll was measured concomitantly with a comparable percentage reduction in light-saturated photosynthesis. Rubisco content and activity were lowered by 10% and 60%, respectively. Antioxidant activity was stimulated by Cd treatment and associated with an increase in the glutathione and pyridine pools, and with a larger pool of reduced glutathione. It is suggested that the glutathione pool and its predominance in the reduced state protected the activity of many key photosynthetic enzymes against the thiophilic binding of Cd. Chloroplast ultrastructure was not significantly altered with 50 µM treatment and the efficiency of PSII, measured as the fluorescence ratio Fv/Fm, remained high because F0 and Fm were proportionally decreased. In plants treated with 100 µM Cd, all effects were exacerbated, but Fv/Fm remained close to that of control leaves and the glutathione and pyridine nucleotides pools were lowered. The results suggest that glutathione exerted a direct important protective role on photosynthesis in the presence of Cd.
Interaction of cadmium with glutathione and photosynthesis in developing leaves and chloroplasts of Phragmites australis
Iannelli MA;Massacci A
2003
Abstract
We investigated how the presence of cadmium (Cd) at the emergence of Phragmites australis (Cav.) Trin. ex Steudel plants from rhizomes interacted with leaf and chloroplast physiological and biochemical processes. About 8.5 nmol Cd per mg of chlorophyll were found in leaves, and 0.83 nmol Cd per mg of chlorophyll in chloroplasts, of plants treated with 50 µM Cd. As a result, a 30% loss of chlorophyll was measured concomitantly with a comparable percentage reduction in light-saturated photosynthesis. Rubisco content and activity were lowered by 10% and 60%, respectively. Antioxidant activity was stimulated by Cd treatment and associated with an increase in the glutathione and pyridine pools, and with a larger pool of reduced glutathione. It is suggested that the glutathione pool and its predominance in the reduced state protected the activity of many key photosynthetic enzymes against the thiophilic binding of Cd. Chloroplast ultrastructure was not significantly altered with 50 µM treatment and the efficiency of PSII, measured as the fluorescence ratio Fv/Fm, remained high because F0 and Fm were proportionally decreased. In plants treated with 100 µM Cd, all effects were exacerbated, but Fv/Fm remained close to that of control leaves and the glutathione and pyridine nucleotides pools were lowered. The results suggest that glutathione exerted a direct important protective role on photosynthesis in the presence of Cd.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
