Aims: Antimony (Sb) is locally found at potentially toxic concentrations in mineralized soils, usually together with arsenic (As). However, local adaptation of plant populations to Sb toxicity has never been shown thus far. Here we compared Sb tolerance and accumulation between a non-metallicolous (NM) population of Salvia spinosa, and a con-specific metallicolous (M) population from a strongly Sb/As-enriched soil in Dashkasan, Iran. Methods: Plants were exposed in hydroponics to a series of Sb[III] and Sb[V] concentrations. After 3 weeks the dry weights and Sb concentrations of roots and shoots were determined. Results: Estimated from the effects on shoot dry weight, the M population was more tolerant than the NM one, particularly to Sb[V], but to a lower degree also to Sb[III]. In both populations Sb[III] was taken up and translocated at higher rates than Sb[V]. The Sb concentrations in roots and shoots were slightly, but significantly higher in the M than in the NM population. Conclusions: Since Sb[V] and As[V] seem to follow very different detoxification pathways, it can be argued that the superior tolerance to Sb[V] in M represents a local adaptation to Sb[V] toxicity itself, rather than being a mere by-product of hypertolerance to its chemical analogue, As[V]. Since Sb[III] and As[III] or As[V] share common detoxification pathways, the apparent Sb[III] hypertolerance in the M population might represent a by-product of As hypertolerance.
- Salvia spinosa