[Heterogeneity of epidermal cells in relation to nickel accumulation in Alyssum hyperaccumulators]

Epidermal cells of some plants are able to accumulate heavy metals (Zn, Ni, Cd) in high concentrations. We have investigated this ability in plants of the genus Alyssum L. differing in tolerance to nickel (Ni). It was found that the preferential accumulation of Ni occurred in the epidermis, whereas in other tissues the metal was detected at lower concentrations. Also it was found that the epidermal cells were characterized by heterogeneity in relation to Ni accumulation, the largest amount of metal accumulated in the large epidermal cells and in trichomes. It was shown species-specific features of Ni distribution in the leaf tissues of Alyssum spp. The reasons of the heterogeneity of epidermal cells in relation to Ni accumulation are discussed. We have attempted to resolve the contradictions encountered in the literature concerning the distribution and accumulation of Ni in the leaf tissues of plants of the genus Alyssum L.