KRZYSZTOF BRZOST, MARIA PIELICHOWSKA (authors of photographs)
MAŁGORZATA WIERZBICKA (project manager)

University of Warsaw,
Faculty of Biology, Institute of Experimental Plant Biology, Department of Ecotoxicology;
Miecznikowa 1, 02-096 Warsaw

e-mail: kszysztofbrzos@biol.uw.edu.pl

Description popularizing the research project

In a nutshell plant vegetation is simply putting its roots into mineral water having checked whether the given ion concentration is within the tolerated ranges. That is how hydroponics works. Soil is simply a mineral nutrient solution mixed with sand.
Plant vegetation on a waste heap means keeping the roots in mineral water where somebody treacherously added a malicious decoct of poisons with heavy metals of lead and cadmium. The roots of plants growing on waste heaps from the very beginning to the very end of their life are soaked in the metal solution. Nobody with the right mind for the sake of their own health would really consider eating a carrot which spent even a single night in water enriched with cadmium. Even an apple, which is supposed to keep a doctor away, from a tree growing on a slag dump would rather resemble the fruit given to the Snow White. That is why Silesian gardeners are advised to grow only decorative plants rather than fruits and vegetables. Together with the valuable elements also the harmful ones enter plant cells. They pose a real threat not only to the plants themselves but to those who eat them as well. Unfortunately the plants cannot block them entry, but they do try to minimize losses and danger for their own metabolism. Poisonous elements once having entered the roots mainly remain there. That is where we can observe them. In large magnification they are revealed as dense, dark stains of fantastic shapes. The plant locks them in these areas of cells where their presence is the least harmful. They are crystallized in vacuoles, in cell walls and between them as in a sieve so they go no further into the plant. That reminds the old proverb: as the twig is bent, so grows the tree.

Abstract

Despite significant improvement of state of our environment in the last 20 years still many regions of Poland, including Silesia, are exposed to the negative influence of industrial waste, accumulated for many years and containing, among others, heavy metals ions such as lead and cadmium. For both animals and plants these ions are very toxic, nevertheless in areas contaminated with these elements one can often observe occurrence of some plant species which had to evolve different adaptations allowing them to exist in such difficult environmental conditions.
The aim of our studies was to determine the level of uptake, ways of the penetration and transport of heavy metals ions in plants and to identify places where these elements are accumulated in plant tissues and cells.
Previous research showed that organs which are especially exposed to heavy metals ions are roots, where the greatest part of uptaken ions is accumulated. Root tissues are responsible for neutralization of uptaken amount of metal ions. The ultrastructural lead localisation in the cells of seedlings root tops of Biscutella laevigata and Armeria maritima (with use of electron microscopy techniques) allowed us to notice presence of numerous deposits of that element in cells of the studied plants. The greatest fraction was accumulated in cell walls, vacuoles and intercellular spaces. Here lead ions were found to appear in large quantity and they often took the shape of different crystal microstructures.
Presented studies have been supported by research grants from Ministry of Science and Higher Education and from University of Warsaw, Faculty of Biology (intramural funds). Presented results were obtained in course of Krzysztof Brzost and Joanna Żyłkowska master theses as well as a part of PhD theses of Maria Pielichowska and Agnieszka Abratowska. All of the theses were done under tuition of Małgorzata Wierzbicka.