Tolerance to heavy metals in plants is a model process used to study adaptations to extremely unfavorable environments. One species capable of colonizing areas with high contents of heavy metals is
...(Mill.) Wild.
plants growing in metalliferous areas differ in their morphological features and tolerance levels to heavy metals compared to individuals of the same species growing in non-metalliferous areas. The
adaptations to heavy metals occur at the organismal, tissue, and cellular levels (e.g., the retention of metals in roots, enrichment of the oldest leaves with metals, accumulation of metals in trichomes, and excretion of metals by salt glands of leaf epidermis). This species also undergoes physiological and biochemical adaptations (e.g., the accumulation of metals in vacuoles of the root's tannic cells and secretion of such compounds as glutathione, organic acids, or HSP17). This work reviews the current knowledge on
adaptations to heavy metals occurring in zinc-lead waste heaps and the species' genetic variation from exposure to such habitats.
is an excellent example of microevolution processes in plants inhabiting anthropogenically changed areas.
Cryopreservation is widely applied to many economically important species excluding chimera plants which are problematic for long-term conservation. Their storage problems can be circumvented only by ...cryopreserving meristems. This study looked at the morphogenetic response of shoot tips of periclinal chimera chrysanthemum ‘Lady Orange’ and ‘Lady Salmon’, as well as the solid mutant ‘Richmond’, that were cryopreserved by encapsulation-dehydration technique. By applying 10 µM ABA in the preculture medium followed by 4-day-long dehydration treatment, the explant survival reached up to 67%. Besides the stimulation of typical single shoot recovery, cryopreservation led to direct or indirect multiple shoot formation, shoot malformation, as well as inhibited their spontaneous rooting. Microscopic analysis revealed three types of structural damages of shoot tips which can correspond with their morphogenetic response in recovery culture. No influence of cryostorage on the acclimatisation efficiency of the recovered chrysanthemums was observed.
Tolerance to heavy metals in plants is a model process used to study adaptations to extremely unfavorable environments. One species capable of colonizing areas with high contents of heavy metals is ...Armeria maritima (Mill.) Wild. A. maritima plants growing in metalliferous areas differ in their morphological features and tolerance levels to heavy metals compared to individuals of the same species growing in non-metalliferous areas. The A. maritima adaptations to heavy metals occur at the organismal, tissue, and cellular levels (e.g., the retention of metals in roots, enrichment of the oldest leaves with metals, accumulation of metals in trichomes, and excretion of metals by salt glands of leaf epidermis). This species also undergoes physiological and biochemical adaptations (e.g., the accumulation of metals in vacuoles of the root's tannic cells and secretion of such compounds as glutathione, organic acids, or HSP17). This work reviews the current knowledge on A. maritima adaptations to heavy metals occurring in zinc-lead waste heaps and the species' genetic variation from exposure to such habitats. A. maritima is an excellent example of microevolution processes in plants inhabiting anthropogenically changed areas.
Heavy metal exposure affect plant productivity by interfering, directly and indirectly, with photosynthetic reactions. The toxic effect of heavy metals on photosynthetic reactions has been reported ...in wide-ranging studies, however there is paucity of data in the literature concerning thallium (Tl) toxicity. Thallium is ubiquitous natural trace element and is considered the most toxic of heavy metals; however, some plant species, such as white mustard (Sinapis alba L.) are able to accumulate thallium at very high concentrations. In this study we identified the main sites of the photosynthetic process inhibited either directly or indirectly by thallium, and elucidated possible detoxification mechanisms in S. alba.
We studied the toxicity of thallium in white mustard (S. alba) growing plants and demonstrated that tolerance of plants to thallium (the root test) decreased with the increasing Tl(I) ions concentration in culture media. The root growth of plants exposed to Tl at 100 μg L(-1) for 4 weeks was similar to that in control plants, while in plants grown with Tl at 1,000 μg L(-1) root growth was strongly inhibited. In leaves, toxic effect became gradually visible in response to increasing concentration of Tl (100 - 1,000 μg L(-1)) with discoloration spreading around main vascular bundles of the leaf blade; whereas leaf margins remained green. Subsequent structural analyses using chlorophyll fluorescence, microscopy, and pigment and protein analysis have revealed different effects of varying Tl concentrations on leaf tissue. At lower concentration partial rearrangement of the photosynthetic complexes was observed without significant changes in the chloroplast structure and the pigment and protein levels. At higher concentrations, the decrease of PSI and PSII quantum yields and massive oxidation of pigments was observed in discolored leaf areas, which contained high amount of Tl. Substantial decline of the photosystem core proteins and disorder of the photosynthetic complexes were responsible for disappearance of the chloroplast grana.
Based on the presented results we postulate two phases of thallium toxicity on photosynthesis: the non-destructive phase at early stages of toxicant accumulation and the destructive phase that is restricted to the discolored leaf areas containing high toxicant content. There was no distinct border between the two phases of thallium toxicity in leaves and the degree of toxicity was proportional to the migration rate of the toxicant outside the vascular bundles. The three-fold (nearly linear) increase of Tl(I) concentration was observed in damaged tissue and the damage appears to be associated with the presence of the oxidized form of thallium - Tl(III).
Heavy metal exposure affect plant productivity by interfering, directly and indirectly, with photosynthetic reactions. The toxic effect of heavy metals on photosynthetic reactions has been reported ...in wide-ranging studies, however there is paucity of data in the literature concerning thallium (Tl) toxicity. Thallium is ubiquitous natural trace element and is considered the most toxic of heavy metals; however, some plant species, such as white mustard (Sinapis alba L.) are able to accumulate thallium at very high concentrations. In this study we identified the main sites of the photosynthetic process inhibited either directly or indirectly by thallium, and elucidated possible detoxification mechanisms in S. alba. We studied the toxicity of thallium in white mustard (S. alba) growing plants and demonstrated that tolerance of plants to thallium (the root test) decreased with the increasing Tl(I) ions concentration in culture media. The root growth of plants exposed to Tl at 100 mug L.sup.-1 for 4 weeks was similar to that in control plants, while in plants grown with Tl at 1,000 mug L.sup.-1 root growth was strongly inhibited. In leaves, toxic effect became gradually visible in response to increasing concentration of Tl (100 - 1,000 mug L.sup.-1) with discoloration spreading around main vascular bundles of the leaf blade; whereas leaf margins remained green. Subsequent structural analyses using chlorophyll fluorescence, microscopy, and pigment and protein analysis have revealed different effects of varying Tl concentrations on leaf tissue. At lower concentration partial rearrangement of the photosynthetic complexes was observed without significant changes in the chloroplast structure and the pigment and protein levels. At higher concentrations, the decrease of PSI and PSII quantum yields and massive oxidation of pigments was observed in discolored leaf areas, which contained high amount of Tl. Substantial decline of the photosystem core proteins and disorder of the photosynthetic complexes were responsible for disappearance of the chloroplast grana. Based on the presented results we postulate two phases of thallium toxicity on photosynthesis: the non-destructive phase at early stages of toxicant accumulation and the destructive phase that is restricted to the discolored leaf areas containing high toxicant content. There was no distinct border between the two phases of thallium toxicity in leaves and the degree of toxicity was proportional to the migration rate of the toxicant outside the vascular bundles. The three-fold (nearly linear) increase of Tl(I) concentration was observed in damaged tissue and the damage appears to be associated with the presence of the oxidized form of thallium - Tl(III).
L. is known as a Tl hyperaccumulator. In Poland
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 (15.2–66.7) mg∙kg
d.m., only (1.1–2.1) mg∙kg
d.m. was present in a bioavailable form. The mean content in all the plants grown on the soil without EDTA was 98.5 mg∙kg
d.m. The largest content was found in leaves – 164.9 mg∙kg
d.m. (max. 588.2 mg∙kg
d.m.). In the case of plants grown on the soil enriched with EDTA, the mean content in plants increased to 108.9 mg∙kg
d.m., max. in leaves – 138.4 mg∙kg
d.m. (max. 1100 mg∙kg
d.m.). 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
d.m.), however, high (>1) translocation and bioconcentration factors suggest such an ability. It is a characteristic species-wide trait;
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.
We investigated physiological and genetic differentiation between local, metallicolous (M) and non-metallicolous (NM) populations of the pseudometallophyte Biscutella laevigata (Brassicaceae) in the ...Tatra Mountains of the Carpathian range and in the northern Carpathian foreland. The investigated plants did not hyperaccumulate Pb, Zn or Cd. Presence of EDTA (ethylenediaminetetraacetic acid) in the substrate caused increased metal uptake (Pb, Zn) only in accessions from the M population. The content of mineral nutrients (Fe, Ca, Mg and K) was decreased in accessions from the M population grown in EDTA-enriched substrate. No significant changes in the metal uptake or mineral status were recorded in plants from the NM population. Genetic variability assessed using amplified fragment length polymorphism (AFLP) was equal in the M and NM populations. No signs of a significant decrease in genetic diversity were found in the M population. There was a strong genetic differentiation between the plants from the M and NM populations, which suggests long-term genetic isolation and vicariance between the populations.
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