Quantitative genetics of zinc hyperaccumulation in Thlaspi caerulescens

We examined variation within and between populations of Thlaspi coerulescens J. & C. Presl (Brassicaceae), a plant species known to hyperaccumulate zinc to foliar concentrations exceeding 3 % (d.wt basis). Seeds were collected as sib families from two populations in Derbyshire, UK 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. Heritability analysis based on resemblance among sibs revealed significant heritable variation within one population, but not the other. The characters of zinc accumulation and plant size were not correlated. Parent-offspring regression did not prove useful for estimation of heritability, because of heterogeneity in metal availability to parents growing in the field. The results are relevant to attempts to exploit metal hyperaccumulation as a technology for remediation of contaminated soil, and to our understanding of the evolutionary origins of the phenomenon of hyperaccumulation.