title: Synchrotron-Based Techniques Shed Light on Mechanisms of Plant Sensitivity and Tolerance to High Manganese in the Root Environment.
abstract: Plant species differ in response to high available manganese (Mn), but the mechanisms of sensitivity and tolerance are poorly understood. In solution culture, greater than or equal to 30 µm Mn decreased the growth of soybean (Glycine max), but white lupin (Lupinus albus), narrow-leafed lupin (Lupin angustifolius), and sunflower (Helianthus annuus) grew well at 100 µm Mn. Differences in species' tolerance to high Mn could not be explained simply by differences in root, stem, or leaf Mn status, being 8.6, 17.1, 6.8, and 9.5 mmol kg(-1) leaf fresh mass at 100 µm Mn. Furthermore, x-ray absorption near edge structure analyses identified the predominance of Mn(II), bound mostly to malate or citrate, in roots and stems of all four species. Rather, differences in tolerance were due to variations in Mn distribution and speciation within leaves. In Mn-sensitive soybean, in situ analysis of fresh leaves using x-ray fluorescence microscopy combined with x-ray absorption near edge structure showed high Mn in the veins, and manganite [Mn(III)] accumulated in necrotic lesions apparently through low Mn sequestration in vacuoles or other vesicles. In the two lupin species, most Mn accumulated in vacuoles as either soluble Mn(II) malate or citrate. In sunflower, Mn was sequestered as manganite at the base of nonglandular trichomes. Hence, tolerance to high Mn was ascribed to effective sinks for Mn in leaves, as Mn(II) within vacuoles or through oxidation of Mn(II) to Mn(III) in trichomes. These two mechanisms prevented Mn accumulation in the cytoplasm and apoplast, thereby ensuring tolerance to high Mn in the root environment.
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia (F.P.C.B., M.C.H.-S., P.M.K.);Centre for AgriBioscience, La Trobe University, Bundoora, Victoria 3086, Australia (M.C., C.T.);Australian Synchrotron, Clayton, Victoria 3168, Australia (D.J.P.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L., W.H.W.); andNational Risk Management Research Laboratory, United States Environmental Protection Agency, Cincinnati, Ohio 45224 (K.G.S.).
authors.forename: F Pax C
authors.identifier: http://orcid.org/0000-0002-6492-1939
authors.initials: FP
authors.lastname: Blamey
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia (F.P.C.B., M.C.H.-S., P.M.K.);Centre for AgriBioscience, La Trobe University, Bundoora, Victoria 3086, Australia (M.C., C.T.);Australian Synchrotron, Clayton, Victoria 3168, Australia (D.J.P.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L., W.H.W.); andNational Risk Management Research Laboratory, United States Environmental Protection Agency, Cincinnati, Ohio 45224 (K.G.S.).
authors.forename: Maria C
authors.initials: MC
authors.lastname: Hernandez-Soriano
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia (F.P.C.B., M.C.H.-S., P.M.K.);Centre for AgriBioscience, La Trobe University, Bundoora, Victoria 3086, Australia (M.C., C.T.);Australian Synchrotron, Clayton, Victoria 3168, Australia (D.J.P.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L., W.H.W.); andNational Risk Management Research Laboratory, United States Environmental Protection Agency, Cincinnati, Ohio 45224 (K.G.S.).
authors.forename: Miaomiao
authors.initials: M
authors.lastname: Cheng
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia (F.P.C.B., M.C.H.-S., P.M.K.);Centre for AgriBioscience, La Trobe University, Bundoora, Victoria 3086, Australia (M.C., C.T.);Australian Synchrotron, Clayton, Victoria 3168, Australia (D.J.P.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L., W.H.W.); andNational Risk Management Research Laboratory, United States Environmental Protection Agency, Cincinnati, Ohio 45224 (K.G.S.).
authors.forename: Caixian
authors.initials: C
authors.lastname: Tang
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia (F.P.C.B., M.C.H.-S., P.M.K.);Centre for AgriBioscience, La Trobe University, Bundoora, Victoria 3086, Australia (M.C., C.T.);Australian Synchrotron, Clayton, Victoria 3168, Australia (D.J.P.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L., W.H.W.); andNational Risk Management Research Laboratory, United States Environmental Protection Agency, Cincinnati, Ohio 45224 (K.G.S.).
authors.forename: David J
authors.identifier: http://orcid.org/0000-0003-0409-9012
authors.initials: DJ
authors.lastname: Paterson
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia (F.P.C.B., M.C.H.-S., P.M.K.);Centre for AgriBioscience, La Trobe University, Bundoora, Victoria 3086, Australia (M.C., C.T.);Australian Synchrotron, Clayton, Victoria 3168, Australia (D.J.P.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L., W.H.W.); andNational Risk Management Research Laboratory, United States Environmental Protection Agency, Cincinnati, Ohio 45224 (K.G.S.).
authors.forename: Enzo
authors.initials: E
authors.lastname: Lombi
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia (F.P.C.B., M.C.H.-S., P.M.K.);Centre for AgriBioscience, La Trobe University, Bundoora, Victoria 3086, Australia (M.C., C.T.);Australian Synchrotron, Clayton, Victoria 3168, Australia (D.J.P.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L., W.H.W.); andNational Risk Management Research Laboratory, United States Environmental Protection Agency, Cincinnati, Ohio 45224 (K.G.S.).
authors.forename: Wei Hong
authors.initials: WH
authors.lastname: Wang
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia (F.P.C.B., M.C.H.-S., P.M.K.);Centre for AgriBioscience, La Trobe University, Bundoora, Victoria 3086, Australia (M.C., C.T.);Australian Synchrotron, Clayton, Victoria 3168, Australia (D.J.P.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L., W.H.W.); andNational Risk Management Research Laboratory, United States Environmental Protection Agency, Cincinnati, Ohio 45224 (K.G.S.).
authors.forename: Kirk G
authors.initials: KG
authors.lastname: Scheckel
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia (F.P.C.B., M.C.H.-S., P.M.K.);Centre for AgriBioscience, La Trobe University, Bundoora, Victoria 3086, Australia (M.C., C.T.);Australian Synchrotron, Clayton, Victoria 3168, Australia (D.J.P.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L., W.H.W.); andNational Risk Management Research Laboratory, United States Environmental Protection Agency, Cincinnati, Ohio 45224 (K.G.S.) p.kopittke@uq.edu.au.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kopittke
mesh_terms: D004777:Environment; D006368:Helianthus / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D031297:Lupinus / Q000502:physiology* / Q000528:radiation effects; D008345:Manganese / Q000378:metabolism*; D018515:Plant Leaves / Q000502:physiology / Q000528:radiation effects; D018517:Plant Roots / Q000502:physiology / Q000528:radiation effects; D018547:Plant Stems / Q000502:physiology / Q000528:radiation effects; D013025:Glycine max / Q000502:physiology* / Q000528:radiation effects; D017356:Synchrotrons; D056928:X-Ray Absorption Spectroscopy
chemical_list: D008345:Manganese