1991 Volume 32 Issue 5 Pages 414-419_1
The uptake of arsenic by the hairy roots of Rubia tinctorum cultured in arsenic-containing medium was studied to estimate the transfer of arsenic to natural dyes produced by means of a tissue-culture technique. When arsenic was added as arsenite in the medium, the growth of the hairy roots was inhibited more strongly than in the case of arsenate. More than 90% of the arsenic added as arsenite to the medium was taken up by the hairy roots after 1 week of incubation. Less than 50% of the arsenic added as arsenate to the medium was taken up by hairy roots after 1 week and, at the highest concentration, about 80% was taken up at 2 weeks. Thus, the uptake of arsenite was faster than that of arsenate. The chemical species of arsenic in the hairy roots were studied by using an HPLC-ICP method. Even arsenic incorporated into the hairy roots from arsenate-containing medium was detected as arsenite. Most arsenic in the hairy roots was not extracted (less than 4% of the total) by methanol, which is a good solvent for the extraction of the anthraquinone pigments produced by R. tinctorum.