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.

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 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.

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.

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.

Light quality has various effects on photochemistry and protein phosphorylation in Zea mays and Arabidopsis thaliana thylakoids due to different degrees of light penetration across leaves and redox status in chloroplasts. The effect of the spectral quality of light (red, R and far red, FR) on the function of thylakoid proteins in Zea mays and Arabidopsis thaliana was investigated. It was concluded that red light stimulates PSII activity in A. thaliana thylakoids and in maize bundle sheath (BS) thylakoids, but not in mesophyll (M) thylakoids. The light quality did not change PSI activity in M thylakoids of maize. FR used after a white light period increased PSI activity significantly in maize BS and only slightly in A. thaliana thylakoids. As shown by blue native (BN)-PAGE followed by SDS-PAGE, proteins were differently phosphorylated in the thylakoids, indicating their different functions. FR light increased dephosphorylation of LHCII proteins in A. thaliana thylakoids, whereas in maize, dephosphorylation did not occur at all. The rate of phosphorylation was higher in maize BS than in M thylakoids. D1 protein phosphorylation increased in maize and decreased in A. thaliana upon irradiation with both R and growth light (white light, W). Light variations did not change the level of proteins in thylakoids. Our data strongly suggest that response to light quality is a species-dependent phenomenon. We concluded that the maize chloroplasts were differently stimulated, probably due to different degrees of light penetration across the leaf and thereby the redox status in the chloroplasts. These acclimation changes induced by light quality are important in the regulation of chloroplast membrane flexibility and thus its function.

We investigated the impact of low zinc (Zn) concentrations in the substare on the onset of flowering in Arabidopsis arenosa (Brassicaceae). Experiments were carried out in controlled conditions using plants from four different populations. The research was aimed to verify experimentally the following hypotheses: (1) Zn content in the growth medium promote the onset of flowering in A. arenosa, (2) Changes in the onset of flowering induced by Zn depend on Zn concentration employed; (3) Zn-induced early onset of flowering is an universal plant response present within the species and is not an effect of stress or physiological adaptation to high Zn content in the environment. Investigated plants were subjected to four different Zn concentrations: 0.4 (control), 155, 775 and 1,550 lM Zn 2? . To asses stress level in investigated plants we calculated biomass accumulation and employed fluorometric methods. Zn content was estimated in shoots using atomic absorption spectroscopy. Differences in the onset of flowering were assessed using Kaplan-Meier curves. Our results showed that Zn was transported form growth medium to roots and shoots of investigated plants and that the content of Zn increased with the increase of Zn concentration in the growth medium. We evidenced that apart from one (1,550 lM Zn 2? ) applied Zn concentrations did not caused stress in investigated plants what was confirmed by two independent experimental approaches: measurement of biomass accumulation and chlorophyll a fluorescence. Flowering curves obtained on the basis of calculation of Kaplan-Meier estimator showed that: (1) control plants originating from four different populations did not differ in terms of the onset of flowering, (2) plants from each population tested tends to enter flowering phase earlier in response to applied Zn concentrations than control plants, (3) plants treated with the lowest tested Zn concentration (155 lM Zn 2? ) tend to flower earlier than plants treated with the higher concentration (775 lM Zn 2? ), (4) the impact of Zn on the onset of flowering did not depend on the origin on the plant material used (Zn-rich or Zn-poor soils). Our results indicate that Zn ions present in the growth medium promote early flowering in A.arenosa and that this effect may depend on Zn concentration used. Zn-induced early flowering in A. arenosa seems to be an universal plant response present within the species and is not an effect of stress or physiological adaptation to high Zn content in the environment.