title: Identification of the primary lesion of toxic aluminum in plant roots.
abstract: Despite the rhizotoxicity of aluminum (Al) being identified over 100 years ago, there is still no consensus regarding the mechanisms whereby root elongation rate is initially reduced in the approximately 40% of arable soils worldwide that are acidic. We used high-resolution kinematic analyses, molecular biology, rheology, and advanced imaging techniques to examine soybean (Glycine max) roots exposed to Al. Using this multidisciplinary approach, we have conclusively shown that the primary lesion of Al is apoplastic. In particular, it was found that 75 µm Al reduced root growth after only 5 min (or 30 min at 30 µm Al), with Al being toxic by binding to the walls of outer cells, which directly inhibited their loosening in the elongation zone. An alteration in the biosynthesis and distribution of ethylene and auxin was a second, slower effect, causing both a transient decrease in the rate of cell elongation after 1.5 h but also a longer term gradual reduction in the length of the elongation zone. These findings show the importance of focusing on traits related to cell wall composition as well as mechanisms involved in wall loosening to overcome the deleterious effects of soluble Al.
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.) p.kopittke@uq.edu.au.
authors: Peter M
authors: PM
authors: Kopittke
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: Katie L
authors: KL
authors: Moore
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: Enzo
authors: E
authors: Lombi
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: Alessandra
authors: A
authors: Gianoncelli
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: Brett J
authors: BJ
authors: Ferguson
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: F Pax C
authors: FP
authors: Blamey
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: Neal W
authors: NW
authors: Menzies
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: Timothy M
authors: TM
authors: Nicholson
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: Brigid A
authors: BA
authors: McKenna
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: Peng
authors: P
authors: Wang
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: Peter M
authors: PM
authors: Gresshoff
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: George
authors: G
authors: Kourousias
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: Richard I
authors: RI
authors: Webb
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: Kathryn
authors: K
authors: Green
authors: Schools of Agriculture and Food Sciences (P.M.K., B.J.F., F.P.C.B., N.W.M., B.A.M., P.W., P.M.G., A.T.) andChemical Engineering (T.M.N.) andCentres for Integrative Legume Research (B.J.F., P.M.G., A.T.) andMicroscopy and Microanalysis (R.I.W., K.G.), University of Queensland, St. Lucia, Queensland 4072, Australia;Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom (K.L.M.);Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia (E.L.); andTwinMic Beamline, Elettra-Sincrotrone Trieste, 34149 Trieste-Basovizza, Italy (A.G., G.K.).
authors: Alina
authors: A
authors: Tollenaere
mesh_terms: D000535:Aluminum / Q000378:metabolism* / Q000633:toxicity; D001692:Biological Transport; D002473:Cell Wall / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D017930:Genes, Reporter; D007210:Indoleacetic Acids / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D036226:Seedlings / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D013025:Glycine max / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*
chemical_list: D005030:Ethylenes; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; C036216:ethylene; D000535:Aluminum