Thallium Hyperaccumulation in Polish Populations of Biscutella laevigata (Brassicaceae)

Abstract

Biscutella laevigata L. is known as a Tl hyperaccumulator. In Poland Biscutella laevigata occurs in the Tatra Mts (Western Carpathians) and on the calamine waste heap in Bolesław near Olkusz (Silesian Upland). The purpose of this work was to evaluate whether plants of both populations were able to accumulate an elevated amount of thallium in their tissues. The plants were cultivated in calamine soil in a glasshouse for a season and studied at different ages -from 2-week-old seedlings to 10-month-old adults. Additionally, the plants were grown for ten weeks in calamine soil with EDTA to enhance Tl bioavailability. The total content of Tl in plant tissues after digestion was determined by ICP-MS, whereas its distribution in leaves was studied by LA-ICP-MS. Of the total content of Tl in the soil in the range of (15. . The translocation factor was 6.1 in the soil and 2.2 in the soil with EDTA; the bioconcentration factor amounted to 10.9 and 5.8, respectively. The plants from both populations did not contain a Tl amount clearly indicating hyperaccumulation (100-500 mg•kg -1 d.m.), however, high (>1) translocation and bioconcentration factors suggest such an ability. It is a characteristic species-wide trait; B. laevigata L. is a facultative Tl hyperaccumulator. The largest Tl amount was located at the leaf base, the smallest at its top. Thallium also occurred in trichomes, which was presented for the first time; in this way plants detoxify Tl in the above-ground parts. Leaves were much more hairy in the Bolesław plants. This is an adaptation for growth in the extreme conditions of the zinc-lead waste heap with elevated Tl quantity.

Microevolution on Anthropogenically Changed Areas on the Example of Biscutella laevigata Plants from Calamine Waste Heap in Poland

“…We can mention here: ability to detoxify metals in protoplast or cell wall, as well as development of "r" reproductive strategies in some species of plants from the metal-bearing areas (formation of plants with a shortened life cycle and rapid entry into the generative phase). Numerous studies show that there are significant differences between populations in heavily contaminated areas and uncontaminated areas, which suggests the emergence of new ecotypes and even new subspecies [1,4,[8][9][10][11][12][13][14][15][16][17][18].…”

“…These are lead-zinc waste heaps in Boleslaw near Olkusz. The third population is located in the lowland in Zagórzyce near Pińczów and is related to the population of Boleslaw [18,21,[26][27][28][29][30][31]. B. laevigata occurs in Poland mainly in mountain rock grassland communities on a substrate containing significant amounts of calcium carbonate [32].…”

“…Both the heap and Tatra populations of B. laevigata are characterized by the ability to hyperaccumulate thallium. In this case, it is a species characteristic [17][18]28].…”

“…All heavy metals present in excessive amounts in the calamine waste heap: zinc, lead, cadmium and thallium were detected in trichomes [4,18].…”

“…The previous studies have shown that two populations of the B. laevigata plants occurring in Poland, at locations 120 km apart, strongly differ from one another with many genetically fixed morphological features [17][18]28,37,60].…”