Methyl mercury toxicity in plant cultures: modification of resistance and demethylation by light and/or 2,4-dichlorophenoxyacetic acid

• Published in: Ecotoxicology and environmental safety Vol. 13; no. 2; p. 191
• Main Author: Czuba, M
• Format: Journal Article
• Language: English
• Published: Netherlands 01-04-1987
• Subjects: 2,4-Dichlorophenoxyacetic Acid - toxicity; Chlorophyll - metabolism; Dealkylation; Light; Mercury - metabolism; Methylmercury Compounds - radiation effects; Methylmercury Compounds - toxicity; Plants
• ISSN: 0147-6513
• DOI: 10.1016/0147-6513(87)90007-8

Cultures of Daucus carota, Ca-68-10, and Lactuca sativa, Le-67, were grown at increasing methyl mercury (MeHg) concentrations ranging from initial doses of 0.05 to 5.0 micrograms/ml per day for 4 days with or without 0.15 microgram/ml 2,4-dichlorophenoxyacetic acid (2,4-D) in the presence or absence of light. The presence of 2,4-D interacted with light synergistically in the expression of MeHg toxicity within the whole range of concentrations. Demethylation patterns increased or decreased depending on the species, the 2,4-D concentration in the medium, and methyl mercury concentration used in the treatment. Lettuce was more sensitive to this interaction than carrot. In lettuce, the presence of 2,4-D in the light lowered the concentration of total Hg (or MeHg) required to reduce growth by 50%, about 13 times relative to that in the dark (i.e., it sensitized the cells). In the absence of 2,4-D the pattern was reversed. In carrot the pattern was similar but less pronounced. This suggests that, in these cell populations, MeHg toxicity is partly a hormone-mediated and light-sensitive event.