No abstract

Changes in the water permeability, aquaporin (AQP) activity, of leaf cells were investigated in response to different heavy metals (Zn2+, Pb2+, Cd2+, Hg2+). The cell pressure probe experiments were performed on onion epidermal cells as a model system. Heavy metal solutions at different concentrations (0.05 μM–2 mM) were used in our experiments. We showed that the investigated metal ions can be arranged in order of decreasing toxicity (expressed as a decrease in water permeability) as follows: Hg>Cd>Pb>Zn. Our results showed that β-mercaptoethanol treatment (10 mM solution) partially reverses the effect of AQP gating. The magnitude of this reverse differed depending on the metal and its concentration. The time course studies of the process showed that the gating of AQPs occurred within the first 10 min after the application of a metal. We also showed that after 20–40 min from the onset of metal treatment, the water flow through AQPs stabilized and remained constant. We observed that irrespective of the metal applied, the effect of AQP gating can be recorded within the first 10 min after the administration of metal ions. More generally, our results indicate that the toxic effects of investigated metal ions on the cellular level may involve AQP gating.

The aim of our study was to reveal biogeographical patterns in the native vascular flora of Iceland and to define ecological factors responsible for these patterns. We analysed dataset of more than 500,000 records containing information on the occurrence of vascular plants. Analysis of ecological factors included climatic (derived from WORLDCLIM data), topographic (calculated from digital elevation model) and geological (bedrock characteristics) variables. Spherical k-means clustering and principal component analysis were used to detect biogeographical patterns and to study the factors responsible for them. We defined 10 biotic elements exhibiting different biogeographical patterns. We showed that climatic (temperature-related) and topographic variables were the most important factors contributing to the spatial patterns within the Icelandic vascular flora and that these patterns are almost completely independent of edaphic factors (bedrock type). Our study is the first one to analyse the biogeographical differentiation of the native vascular flora of Iceland.

We investigated the influence of cadmium stress on zinc hyperaccumulation, mineral nutrient uptake, and the content of metal-binding proteins in Arabidopsis halleri. The experiments were carried out using plants subjected to long-term cadmium exposure (40 days) in the concentrations of 45 and 225 μM Cd2+. Inductively coupled plasma-mass spectrometry, size exclusion chromatography coupled with plasma-mass spectrometry, and laser ablation inductively coupled plasma-mass spectrometry used for ablation of polyacylamide gels were employed to assess the content of investigated elements in plants as well as to identify metal-binding proteins. We found that A. halleri is able to translocate cadmium to the aerial parts in high amounts (translocation index >1). We showed that Zn content in plants decreased significantly with the increase of cadmium content in the growth medium. Different positive and negative correlations between Cd content and mineral nutrients were evidenced by our study. We identified more than ten low-molecular-weight (<100 kDa) Cd-binding proteins in Cd-treated plants. These proteins are unlikely to be phytochelatins or metallothioneins. We hypothesize that low-molecular-weight Cd-binding proteins can be involved in cadmium resistance in A. halleri.Electronic supplementary materialThe online version of this article (doi:10.1007/s11270-012-1292-4) contains supplementary material, which is available to authorized users.

The present study aimed to investigate phylogeographical patterns present within A.halleri in Central Europe, to propose hypotheses explaining the emergence of these patterns and to formulate hypotheses on the formation of the present day range of A.halleri in the region. 1281 accessions sampled from 52 populations within the investigated area were used in the study of genetic variation based on chloroplast DNA. Over 500 high quality species occurrence records were used in ecological niche modelling experiments.We evidenced the presence of a clear phylogeographic structure within A. halleri in Central Europe. Our results suggest that the species might have not survived the last glacial maximum in the Carpathians and Sudetes and that its range during the last glacial maximum might have consisted of at least two major parts: (1) a northern refugium consisting of vast refugial areas north and northeast of the Alps and (2) a southern refugium located in the Dinaric Alps and Balkan Mts. We postulate that the Sudetes and Western Carpathians were colonised mainly by plants originating from the northern refugium, whereas populations from the Eastern Carpathians originate from southern refugium. We also discuss our results in relation to the problematic taxonomy of the species. that its range during the last glacial maximum might have consisted of at least two major parts: 10(1) a northern refugium consisting of vast refugial areas north and northeast of the Alps and (2) a 11 southern refugium located in the Dinaric Alps and Balkan Mts. We postulate that the Sudetes and 12Western Carpathians were colonised mainly by plants originating from the northern refugium, 13whereas populations from the Eastern Carpathians originate from southern refugium. We also 14 discuss our results in relation to the problematic taxonomy of the species.