Evidence for PSII donor-side damage and photoinhibition induced by cadmium treatment on rice (Oryza sativa L.).
The effects of cadmium (from 7.5 to 75 microM) on chloroplasts of rice were studied at the structural and biochemical level. Loss of pigments, reduction of thylakoids and decrease in oxygen evolution and Fv/Fm ratio occur in leaves following cadmium treatment. However, the amount of photosystem II reaction center proteins and that of its light harvesting complex is not affected, indicating that cadmium does not adversely influence the structural organization of this photosystem. In thylakoids isolated from cadmium-treated plants a loss in the capability to reduce 2,6-dichlorophenolindophenol is observed, which is partially restored if diphenylcarbazide is used as an electron donor, indicating that cadmium affects water splitting activity. In thylakoids isolated from control plants and treated with cadmium, diphenylcarbazide preserves most of the photosystem II activity lost after incubation with cadmium; most of the S(2) multiline electron paramagnetic resonance signal from the manganese cluster is lost, whereas the TyrD(+) and other signals are retained. Light-induced photosystem II damage, in vitro, is promoted by Cd-treatment as deduced from the mobility shift of the D1 protein observed by immunoblot.
Dipartimento di Scienze dell Ambiente e della Vita, Università del Piemonte Orientale Amedeo Avogadro,Via Bellini 25G, I-15100 Alessandria, Italy.
Cristina
C
Pagliano
Marco
M
Raviolo
Francesca
F
Dalla Vecchia
Roberto
R
Gabbrielli
Cristina
C
Gonnelli
Nicoletta
N
Rascio
Roberto
R
Barbato
Nicoletta
N
La Rocca
D002104:Cadmium / Q000494:pharmacology*; D002736:Chloroplasts / Q000187:drug effects / Q000648:ultrastructure; D004160:Diphenylcarbazide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004578:Electron Spin Resonance Spectroscopy; D024202:Electrophoretic Mobility Shift Assay; D008027:Light; D046529:Microscopy, Electron, Transmission; D012275:Oryza / Q000737:chemistry* / Q000187:drug effects; D010100:Oxygen / Q000737:chemistry; D045332:Photosystem II Protein Complex / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure*; D018515:Plant Leaves / Q000648:ultrastructure; D020524:Thylakoids / Q000737:chemistry* / Q000187:drug effects
D045332:Photosystem II Protein Complex; D002104:Cadmium; D004160:Diphenylcarbazide; D010100:Oxygen