Distribution and speciation of Mn in hydrated roots of cowpea at levels inhibiting root growth |
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Authors: | Peter M. Kopittke Enzo Lombi Brigid A. McKenna Peng Wang Erica Donner Richard I. Webb F. Pax C. Blamey Martin D. de Jonge David Paterson Daryl L. Howard Neal W. Menzies |
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Affiliation: | 1. The University of Queensland, School of Agriculture and Food Sciences, , St. Lucia, Queensland, 4072 Australia;2. Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC‐CARE), , Salisbury South, South Australia, 5106 Australia;3. University of South Australia, Centre for Environmental Risk Assessment and Remediation, , Mawson Lakes, South Australia, 5095 Australia;4. The University of Queensland, Australian Institute for Bioengineering and Nanotechnology, Centre for Microscopy and Microanalysis, , St Lucia, Queensland, 4072 Australia;5. Australian Synchrotron, , Clayton, Victoria, 3168 Australia |
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Abstract: | The phytotoxicity of Mn is important globally due to its increased solubility in acid or waterlogged soils. Short‐term (≤24 h) solution culture studies with 150 µM Mn were conducted to investigate the in situ distribution and speciation of Mn in apical tissues of hydrated roots of cowpea [Vigna unguiculata (L.) Walp. cv. Red Caloona] using synchrotron‐based techniques. Accumulation of Mn was rapid; exposure to 150 µM Mn for only 5 min resulting in substantial Mn accumulation in the root cap and associated mucigel. The highest tissue concentrations of Mn were in the root cap, with linear combination fitting of the data suggesting that ≥80% of this Mn(II) was associated with citrate. Interestingly, although the primary site of Mn toxicity is typically the shoots, concentrations of Mn in the stele of the root were not noticeably higher than in the surrounding cortical tissues in the short‐term (≤24 h). The data provided here from the in situ analyses of hydrated roots exposed to excess Mn are, to our knowledge, the first of this type to be reported for Mn and provide important information regarding plant responses to high Mn in the rooting environment. |
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