Intraspecific variation of nickel and zinc accumulation and tolerance in the hyperaccumulator Thlaspi caerulescens

Abstract

Plants from two contrasting populations of the hyperaccumulator Thlaspi caerulescens, one from the serpentine area of Monte Prinzera (MP) in northern Italy and a Belgian calamine population, La Calamine (LC), were crossed to study the genetic correlation of Ni and Zn accumulation as well as Ni accumulation and Ni tolerance. Parental populations and F3 and F4 progeny of the interpopulation cross were phenotyped. The phenotype distributions for Zn and Ni accumulation of the parental populations were non-overlapping, with MP having higher foliar metal concentrations than LC. Ni tolerance was also higher in MP, but the parental distributions were overlapping. The F3 and F4 progeny exhibited a clear segregation for the Ni and Zn accumulation trait as well as for Ni tolerance. Variance and covariance analysis of the F3 progeny demonstrated significant heritability values (h2) for Ni and Zn foliar accumulation (0.70 and 0.59, respectively) and Ni tolerance (0.47), as well as a significant positive genetic correlation between the foliar accumulation of Ni and Zn (rA2 = 0.82). Ni tolerance and Ni accumulation were uncorrelated. Regressing the F4 family means on the F3 parent values yielded similar estimates for the heritabilities of Ni and Zn accumulation in the leaves (0.66 and 0.55, respectively)