Cadmium Accumulation by Plants of Brassicaceae Family and Its Connection with Their Primary and Secondary Metabolism

Abstract

The mustard family – Brassicaceae – is well known as family of plants, metallophytes, which are able to accumulate wide range of heavy metals and metalloids, especially zinc and cadmium, but also nickel, thallium, chromium and selenium. Ecological importance of this process consists partially in plants themselves to survive negative environmental conditions. There are two basic different strategies, how to survive these conditions – accumulation of heavy metals in plants tissues with different intensity in individual cell types, but also organs, which is partially given by chemical composition of cell walls, and ability to synthesize special defensive – detoxification compounds rich on thiol groups – glutathione and phytochelatins, which are able to bind heavy metals and transport them to the “secure” cell compartment – vacuole. The second principle is based on ability to exclude heavy metals. Role of secondary metabolites rich on sulphur in detoxification of heavy metals is still discussed with unclear conclusions. Members of Brassicaceae family, especially genera Thlaspi and Brassica, are well-known hyperaccumulators of heavy metals with possible utilization in phytoremediation technologies. In this review chapter, mechanisms of cadmium uptake and transport and its deposition in various plant cells and tissues are discussed with respect with possible utilization in phytoremediation. In addition, role of special sulphur metabolites, which are typical for plants of Brassicaceae family – glucosinolates – in detoxification of heavy metals is discussed.