Plants from metalliferous soils often exhibit combined tolerance to
different heavy metals. Such tolerance could
rely either on the possession of a combination of different metal-specific
tolerance mechanisms (‘multiple
tolerance’), or on less specific mechanisms that pleiotropically
confer tolerance to different metals (‘co-tolerance’).
In this study, we examined the co-segregation of tolerances to Cu, Zn, Ni,
Co and Cd in crosses between distinctly
tolerant ecotypes of Silene vulgaris (Moench) Garcke. The results
demonstrate non-pleiotropic genetic control of
tolerance to Cu, Zn and Cd. Tolerance to Ni and Co, on the other hand,
seems to represent the pleiotropic by-product of the tolerance allele
of one particular locus for zinc tolerance.