Influence of zinc hyperaccumulation on glucosinolates in Thlaspi caerulescens

Previous investigations suggest that in species of the Brassicaceae hyperaccumulation of heavy metals might provide an ecological advantage by protecting the plants against herbivores and/or pathogens while lowering the glucosinolate content. Few analytical data on glucosinolate concentrations in hyperaccumulators are available for supporting this 'trade-off' hypothesis. This is the first report on the influence of zinc (Zn) hyperaccumulation on the concentrations of individual glucosinolates in Thlaspi caerulescens exposed to different Zn concentrations. The most abundant glucosinolate within both roots and shoots was p-hydroxybenzyl glucosinolate (sinalbin). Zn hyperaccumulation decreased sinalbin concentrations in shoots, whereas root concentrations increased with Zn accumulation. These changes in sinalbin concentrations were mainly responsible for Zn-induced alterations of total glucosinolate contents. Quantitatively less important was a Zn-induced decrease of indolylglucosinolates observed in both roots and shoots and that of 3-butenylglucosinolate found in roots. The results presented here support the view of a trade-off between Zn and glucosinolates in shoots but not in roots of Thlaspi caerulescens. (C) New Phytologist (2001).