68 research outputs found
Nickel biopathways in tropical nickel hyperaccumulating trees from Sabah (Malaysia)
The extraordinary level of accumulation of nickel (Ni) in hyperaccumulator plants is a consequence of specific metal sequestering and transport mechanisms, and knowledge of these processes is critical for advancing an understanding of transition element metabolic regulation in these plants. The Ni biopathways were elucidated in three plant species, Phyllanthus balgooyi, Phyllanthus securinegioides (Phyllanthaceae) and Rinorea bengalensis (Violaceae), that occur in Sabah (Malaysia) on the Island of Borneo. This study showed that Ni is mainly concentrated in the phloem in roots and stems (up to 16.9% Ni in phloem sap in Phyllanthus balgooyi) in all three species. However, the species differ in their leaves - in P. balgooyi the highest Ni concentration is in the phloem, but in P. securinegioides and R. bengalensis in the epidermis and in the spongy mesophyll (R. bengalensis). The chemical speciation of Ni(2+) does not substantially differ between the species nor between the plant tissues and transport fluids, and is unambiguously associated with citrate. This study combines ion microbeam (PIXE and RBS) and metabolomics techniques (GC-MS, LC-MS) with synchrotron methods (XAS) to overcome the drawbacks of the individual techniques to quantitatively determine Ni distribution and Ni(2+) chemical speciation in hyperaccumulator plants.Antony van der Ent, Damien L. Callahan, Barry N. Noller, Jolanta Mesjasz-Przybylowicz, Wojciech J. Przybylowicz, Alban Barnabas and Hugh H. Harri
Nodules from fynbos legume Virgilia divaricata have high functional plasticity under variable P supply levels
Legumes have the unique ability to fix atmospheric nitrogen (N2) via symbiotic bacteria in their nodules
but depend heavily on phosphorus (P), which affects nodulation, and the carbon costs and energy
costs of N2 fixation. Consequently, legumes growing in nutrient-poor ecosystems (e.g., sandstone-derived
soils) have to enhance P recycling and/or acquisition in order to maintain N2 fixation. In this study,
we investigated the flexibility of P recycling and distribution within the nodules and their effect on N
nutrition in Virgilia divaricata Adamson, Fabaceae, an indigenous legume in the Cape Floristic Region
of South Africa. Specifically, we assessed tissue elemental localization using micro-particle-induced
X-ray emission (PIXE), measured N fixation using nutrient concentrations derived from inductively coupled
mass-spectrometry (ICP-MS), calculated nutrient costs, and determined P recycling from enzyme
activity assays. Morphological and physiological features characteristic of adaptation to P deprivation
were observed for V. divaricata. Decreased plant growth and nodule production with parallel increased
root:shoot ratios are some of the plastic features exhibited in response to P deficiency. Plants resupplied
with P resembled those supplied with optimal P levels in terms of growth and nutrient acquisition. Under
low P conditions, plants maintained an increase in N2-fixing efficiency despite lower levels of orthophosphate
(Pi) in the nodules. This can be attributed to two factors: (i) an increase in Fe concentration under
low P, and (ii) greater APase activity in both the roots and nodules under low P. These findings suggest
that V. divaricata is well adapted to acquire N under P deficiency, owing to the plasticity of its nodule
physiologyDST-NRF Centre of Excellence in Tree Health Biotechnology(CTHB).http://www.elsevier.com/locate/jplpham201
\u3ci\u3eSenecio Conrathii\u3c/i\u3e N.E.Br. (Asteraceae), a New Hyperaccumulator of Nickel from Serpentinite Outcrops of the Barberton Greenstone Belt, South Africa
Five nickel hyperaccumulators belonging to the Asteraceae are known from ultramafic outcrops in South Africa. Phytoremediation applications of the known hyperaccumulators in the Asteraceae, such as the indigenous Berkheya coddii Roessler, are well reported and necessitate further exploration to find additional species with such traits. This study targeted the most frequently occurring species of the Asteraceae on eight randomly selected serpentinite outcrops of the Barberton Greenstone Belt. Twenty species were sampled, including 12 that were tested for nickel accumulation for the first time. Although the majority of the species were excluders, the known hyperaccumulators Berkheya nivea N.E.Br. and B. zeyheri (Sond. & Harv.) Oliv. & Hiern subsp. rehmannii (Thell.) Roessler var. rogersiana (Thell.) Roessler hyperaccumulated nickel in the leaves at expected levels. A new hyperaccumulator of nickel was discovered, Senecio conrathii N.E.Br., which accumulated the element in its leaves at 1695 ± 637 µg g−1 on soil with a total and exchangeable nickel content of 503 mg kg−1 and 0.095 µg g−1, respectively. This makes it the third known species in the Senecioneae of South Africa to hyperaccumulate nickel after Senecio anomalochrous Hilliard and Senecio coronatus (Thunb.) Harv., albeit it being a weak accumulator compared with the latter. Seven tribes in the Asteraceae have now been screened for hyperaccumulation in South Africa, with hyperaccumulators only recorded for the Arctoteae and Senecioneae. This suggests that further exploration for hyperaccumulators should focus on these tribes as they comprise all six species (of 68 Asteraceae taxa screened thus far) to hyperaccumulate nickel
Metal imaging on surface of micro- and nanoelectronic devices by laser ablation inductively coupled plasma mass spectrometry and possibility to measure at nanometer range
Comparison of ultrastructure, histochemistry and Ni distribution in leaves of Ni-hyperaccumulating and non-hyperaccumulating genotypes of Senecio coronatus
Comparison of Cytology and Elemental Distribution in Chlorotic and Non-Chlorotic Parts of Leaves of the Ni Hyperaccumulator Berkheya coddii
Studies on spatial distribution of nickel in leaves and stems of the metal hyperaccumulator Stackhousia tryonii Bailey using nuclear microprobe (micro-PIXE) and EDXS techniques
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