Arsenic metabolism in freshwater and terrestrial plants

Freshwater and terrestrial plants differ markedly in their ability to metabolize arsenate. In experiments with higher terrestrial plants, e.g. tomato, Lycopersicon esculentum Mill. cv. Better boy, 74 As‐arsenate was readily taken up and reduced to arsenite. Methylation and reduction to methanearsonic acid, methanearsinic acid (indicated for the first time) and dimethylarsinic acid were apparent only in phosphate deficient plants. Lower and higher freshwater plants, e.g. Nitella tenuissima Kütz. and Lemna minima Phill., not only methylated arsenic but also produced considerable amounts of an arsoniumphospholipid previously identified in marine algae. These differences indicate that freshwater but not terrestrial plants have evolved mechanisms for rapid detoxication of arsenate, arsenite and other toxic arsenic species.