An arsenic-accumulating, hypertolerant brassica, Isatis capadocica
Author for correspondence:
A. A. Meharg
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- • Isatis capadocica, a brassica collected from Iranian arsenic-contaminated mine spoils and control populations, was examined to determine arsenate tolerance, metabolism and accumulation.
- • I. cappadocica exhibited arsenate hypertolerance in both mine and nonmine populations, actively growing at concentrations of > 1 mm arsenate in hydroponic solution.
- • I. cappadocica had an ability to accumulate high concentrations of arsenic in its shoots, in excess of 100 mg kg−1 DW, with a shoot : root transfer ratio of > 1. The ability to accumulate arsenic was exhibited in both hydroponics and contaminated soils.
- • Tolerance in this species was not achieved through suppression of high-affinity phosphate/arsenate root transport, in contrast to other monocotyledons and dicotyledons. A high percentage (> 50%) of arsenic in the tissues was phytochelatin complexed; however, it is argued that this is a constitutive, rather than an adaptive, mechanism of tolerance.