QUANTITATIVE GENETICS OF ZINC HYPERACCUMULATION IN THLASPI-CAERULESCENS

We examined variation within and between populations of Thlaspi coerul escens J. & C. Presl (Brassicaceae), a plant species known to hyperacc umulate zinc to foliar concentrations exceeding 3 % (d.wt basis). Seed s were collected as sib families from two populations in Derbyshire, U K along with leaf samples from the parent plants. Offspring were grown hydroponically from seed, in culture solution containing 10 mg l(-1) Zn. Significant differences in zinc concentration and plant size were found between populations and among sib families within populations. H eritability analysis based on resemblance among sibs revealed signific ant heritable variation within one population, but not the other. The characters of zinc accumulation and plant size were not correlated. Pa rent-offspring regression did not prove useful for estimation of herit ability, because of heterogeneity in metal availability to parents gro wing in the field. The results are relevant to attempts to exploit met al hyperaccumulation as a technology for remediation of contaminated s oil, and to our understanding of the evolutionary origins of the pheno menon of hyperaccumulation.