The acclimatization strategies of kidney vetch (Anthyllis vulneraria L.) to Pb toxicity.

Kidney vetch (Anthyllis vulneraria L.) is a well-known Zn hyperaccumulator. Zn often occurs with Pb in one ore; thus, plants inhabiting waste dumps are exposed not only to Zn but also to Pb toxicity. While the response of kidney vetch to Zn toxicity is relatively well known, the Pb survival strategy of Anthyllis vulneraria has not been the subject of investigations. The aim of presented research was to determine the survival strategy of kidney vetch exposed to high lead concentrations. Shoot explants of a calamine kidney vetch ecotype were placed on agar media containing 0.0, 0.5, 1.0, and 1.5 mM Pb. Morphological, physiological, and biochemical responses, in particular photosynthetic apparatus of plantlets, were examined. The most pronounced changes were observed in plants grown on media supplemented with 1.5 mM Pb after 8 weeks of culture. Increased dry weight and high lead accumulation were observed in roots. Similarly, in shoots, increased dry weight and a decreased number of newly formed shoots were recorded. The accumulation of lead was many times lower in shoots than in roots. In leaf cells' ultra-structure, looser arrangement of chloroplast thylakoid grana was observed. Despite the decrease in chlorophyll a and carotenoid content, the photosynthetic apparatus remained efficient due to the lack of photoinhibition and increased electron transport rate beyond photosystem II (PSII). For the first time, an acclimatization mechanism based on maintaining the high efficiency of photosynthetic apparatus resulting from increasing of electron transport rate was described.

Callitriche cophocarpa (water starwort) proteome under chromate stress: evidence for induction of a quinone reductase.

Chromate-induced physiological stress in a water-submerged macrophyte Callitriche cophocarpa Sendtn. (water starwort) was tested at the proteomic level. The oxidative stress status of the plant treated with 1 mM Cr(VI) for 3 days revealed stimulation of peroxidases whereas catalase and superoxide dismutase activities were similar to the control levels. Employing two-dimensional electrophoresis, comparative proteomics enabled to detect five differentiating proteins subjected to identification with mass spectrometry followed by an NCBI database search. Cr(VI) incubation led to induction of light harvesting chlorophyll a/b binding protein with a concomitant decrease of accumulation of ribulose bisphosphate carboxylase (RuBisCO). The main finding was, however, the identification of an NAD(P)H-dependent dehydrogenase FQR1, detectable only in Cr(VI)-treated plants. The FQR1 flavoenzyme is known to be responsive to oxidative stress and to act as a detoxification protein by protecting the cells against oxidative damage. It exhibits the in vitro quinone reductase activity and is capable of catalyzing two-electron transfer from NAD(P)H to several substrates, presumably including Cr(VI). The enhanced accumulation of FQR1 was chromate-specific since other stressful conditions, such as salt, temperature, and oxidative stresses, all failed to induce the protein. Zymographic analysis of chromate-treated Callitriche shoots showed a novel enzymatic protein band whose activity was attributed to the newly identified enzyme. We suggest that Cr(VI) phytoremediation with C. cophocarpa can be promoted by chromate reductase activity produced by the induced quinone oxidoreductase which might take part in Cr(VI) â†’ Cr(III) bioreduction process and thus enable the plant to cope with the chromate-generated oxidative stress.

From laboratory to field studies - The assessment of Biscutella laevigata suitability to biological reclamation of areas contaminated with lead and cadmium.

The aim of the work was to evaluate the usefulness of the in vitro multiplication of Biscutella laevigata calamine ecotype for in situ reclamation of post-flotation wastes polluted with Pb and Cd. The experiment was conducted on three steps: (i) plant shoots' production under in vitro condition, (ii) establishment of the material in greenhouse experiment, and finally (iii) field cultivation directly on the mining-waste heap of Olkusz Ore-Bearing Region, Poland. This region is known to be one of the most chemically-degraded area in central Europe. The laboratory-set in vitro analysis enabled to obtain the high-quality plant shoots, which multiply the most effectively (with growth tolerance index 130-150%) on medium containing 5.0µM CdCl2 and 0.5mM Pb(NO3)2. These plants were used for the next two ex vitro experiments. Several biometric and physiological analysis (i.e. of photosystem II activity Fv/Fm and PI, photosynthetic pigment contents) were done to indicate plant physiological status during these experiments. The main novelty of the work was to prove that in vitro-multiplied shoots of B. laevigata - the representative of native flora from Olkusz Ore-Bearing Region - can be successfully implemented in situ for the restoration of these degraded area. Moreover, the addition of sewage sludge as a source of organic compounds significantly improved plants' growth and development what is especially important due to the lack of other legal solutions for the management of the sewage sludge in some countries.