The Nickel Hyperaccumulating Plants of the Serpentines of Turkey and Adjacent Areas: A Review with New Data

Botanical exploration of serpentine soils in Turkey and neighbouring countries has shown that the region includes at least59 taxa capable of hyperaccumulating nickel (to 0.1% of plant dry weight). These hyperaccumulators belong to the Brassicaceae(Aethionema R.Br., Alyssum L., Bornmuellera Hausskn., Pseudosempervivum (Boiss.) Grossh. (Cochlearia L.), and Thlaspi L. s.l.) andthe Asteraceae (Centaurea L.). We review present knowledge of the hyperaccumulators and provide additional data recently obtained.Some species are serpentine-endemic and invariably Ni hyperaccumulating; others show more complex distribution and Niaccumulating behaviour. Many are good subjects for biochemical studies on the Ni-accumulation and sequestering processes. Thereis potential in Turkey for exploiting Ni hyperaccumulation for remediation of Ni-contaminated soils (‘phytoremediation’) and foreconomical selective extraction of metal compounds by cropping hyperaccumulators (‘phytomining’). However, there is a need forfurther exploration of the natural resources and some further taxonomic work by traditional and DNA methods. Attention must bepaid to conservation issues, as some of the relevant species are quite rare.