Co-Promotor: Dr. M.G.M. Aarts
Co-Promotor: Dr. H. Schat (VU, Amsterdam)
Although metal homeostasis is supposed to be universal within plants, there are plant species that can tolerate and even accumulate large amounts of metals without any sign of toxicity. Thlaspi caerulescens, a close relative of the general plant reference species Arabidopsis (Arabidopsis thaliana), is a natural zinc/nickel/cadmium hyperaccumulator species. During my thesis research I tried to find answer to the major question: How it is possible that two plant species that are closely related, have such different properties regarding uptake, accumulation and detoxification of zinc, nickel and cadmium? I addressed this question by comparing gene expression of Arabidopsis and T. caerulescens and of two different accessions of T. caerulescens, exposed to a range of different zinc and/or cadmium concentrations in their growing medium using microarray hybridizations. This showed striking differences between the species and also differences between accessions, particularly in the way they control expression of genes involved in metal homeostasis, abiotic stress response or in lignin- or glutathione- or sulfate biosynthesis. In addition, many genes with differential expression were identified that until now have not been associated with a particular biochemical process and for which a function still needs to be determined. When additional knowledge on the nature of these genes is obtained, the outcome of this research might be applied to equip plants with properties that make them suitable for remediation of soil which is polluted with zinc or cadmium (phytoremediation) or for enhancing the accumulation of essential minerals such as iron and zinc in food crops for providing these with improved nutrition qualities (biofortification).
Title thesis: Heavy metal tolerance and accumulation in Thlaspi caerulescens, a heavy metal hyperaccumulating plant species