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A gene in the multidrug and toxic compound extrusion (MATE) family confers aluminum tolerance in sorghum


Crop yields are significantly reduced by aluminum toxicity on highly acidic soils, which comprise up to 50% of the world's arable land1,2,3. Candidate aluminum tolerance proteins include organic acid efflux transporters, with the organic acids forming non-toxic complexes with rhizosphere aluminum1,4. In this study, we used positional cloning to identify the gene encoding a member of the multidrug and toxic compound extrusion (MATE) family, an aluminum-activated citrate transporter, as responsible for the major sorghum (Sorghum bicolor) aluminum tolerance locus, AltSB5. Polymorphisms in regulatory regions of AltSB are likely to contribute to large allelic effects, acting to increase AltSB expression in the root apex of tolerant genotypes. Furthermore, aluminum-inducible AltSB expression is associated with induction of aluminum tolerance via enhanced root citrate exudation. These findings will allow us to identify superior AltSB haplotypes that can be incorporated via molecular breeding and biotechnology into acid soil breeding programs, thus helping to increase crop yields in developing countries where acidic soils predominate.

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Figure 1: Positional cloning of AltSB.
Figure 2: Expression and localization of SbMATE.
Figure 3: Correlation of SbMATE expression, root citrate exudation and aluminum tolerance in ten sorghum lines that harbor an allelic series at AltSB (BR012, BR007, IS8577, SC549, 3DX, SC175, 9DX, CMS225, SC283, SC566)10 exposed to {27} μM Al3+ in nutrient solution.
Figure 4: Expression of SbMATE in transgenic A. thaliana plants.


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The authors thank J. Giovannoni and E. Buckler for critically reading the manuscript and J. Essig and M. Wohler for their technical support with wheat tissue culture and wheat genetic engineering. The work was supported by Generation Challenge Program grant IC69, US Department of Agriculture–National Research Initiative Competitive grant 2006-35301-16884, a McKnight Foundation Collaborative Crop Research Program grant and a FAPEMIG–Brazil grant.

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Authors and Affiliations



J.V.M. and L.V.K. shared equally in the work, including the direction and oversight of the research and writing of the paper and, thus, are both equally contributing first authors and corresponding authors. J.L., C.T.G., U.G.P.L., Y.-H.W. and P.E.K. contributed to the positional cloning of AltSB, and J.L. conducted the real-time PCR analysis and generation and characterization of transgenic A. thaliana. U.G.P.L. and C.M.C. conducted the RT-PCR analysis of AltSB expression in the diversity panel. V.M.C.A. and J.E.S. conducted the analysis of sorghum root organic acid exudation, and J.E.S. conducted the A. thaliana root organic acid analysis. R.E.S. generated the mapping populations and NILs. O.A.H. contributed to the analysis of A. thaliana Al tolerance and organic acid exudation, and M.A.P. conducted the AltSB-GFP protein localization and expression and electrophysiological characterization of SbMATE in Xenopus laevis oocytes.

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Correspondence to Jurandir V Magalhaes or Leon V Kochian.

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The authors declare no competing financial interests.

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Supplementary Methods, Supplementary Note, Supplementary Tables 1–2, Supplementary Figures 1–4 (PDF 692 kb)

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Magalhaes, J., Liu, J., Guimarães, C. et al. A gene in the multidrug and toxic compound extrusion (MATE) family confers aluminum tolerance in sorghum. Nat Genet 39, 1156–1161 (2007).

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