Different compensatory mechanisms in two metal-accumulating aquatic macrophytes exposed to acute cadmium stress in outdoor artificial lakes.
Mechanisms underlying cadmium (Cd) detoxification were compared in two aquatic macrophytes commonly used in phytoremediation, namely Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms. To simulate Cd pollution in the open environment, plants growing in outdoor artificial lakes were exposed for 21d to either 25 or 100microM Cd, in two consecutive years. Toxicity symptoms were absent or mild in both species. Metal accumulation was much higher in the roots of P. stratiotes, whereas in E. crassipes a comparatively higher fraction was translocated to the leaves. In both species, Cd was neither included in phenolic polymers or Ca-oxalate crystals, nor altered the levels of Cd-complexing organic acids. Glutathione levels were constitutively remarkably higher and much more responsive to Cd exposure in P. stratiotes than in E. crassipes. Abundant phytochelatin synthesis occurred only in P. stratiotes, both in roots and in leaves. In E. crassipes, on the other side, the constitutive levels of some antioxidant enzymes and ascorbate were higher and more responsive to Cd than in P. stratiotes. Thus, in these two aquatic plants grown in the open, different detoxification mechanisms might come into play to counterbalance Cd acute stress.
Sanità di Toppi
Luigi
L
Dipartimento di Biologia Evolutiva e Funzionale, Università di Parma, 43100 Parma, Italy. sanita@biol.unipr.it
Vurro
Emanuela
E
Rossi
Laura
L
Marabottini
Rosita
R
Musetti
Rita
R
Careri
Maria
M
Maffini
Monica
M
Mucchino
Claudio
C
Corradini
Claudio
C
Badiani
Maurizio
M
D029064:Araceae / Q000378:metabolism*; D060387:Ascorbate Peroxidases; D001205:Ascorbic Acid / Q000378:metabolism; D001673:Biodegradation, Environmental; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity; D002374:Catalase / Q000378:metabolism; D031806:Eichhornia / Q000378:metabolism*; D005618:Fresh Water; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000378:metabolism* / Q000633:toxicity
D014874:Water Pollutants, Chemical; D002104:Cadmium; D010088:Oxidoreductases; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D009247:NADH, NADPH Oxidoreductases; C023927:monodehydroascorbate reductase (NADH); C020666:glutathione dehydrogenase (ascorbate); D005978:Glutathione; D001205:Ascorbic Acid