PP66CH23-Kochian ARI 15 January 2015 11:1 R E V I E W S I N A D V A N C E Plant Adaptation to Acid Soils: The Molecular Basis for Crop Aluminum Resistance Leon V. Kochian, 1 Miguel A. Pi ˜ neros, 1 Jiping Liu, 1 and Jurandir V. Magalhaes 2 1 Robert W. Holley Center for Agriculture and Health, USDA-ARS, Cornell University, Ithaca, New York 14853; email: lvk1@cornell.edu, map25@cornell.edu, jl233@cornell.edu 2 Embrapa Maize and Sorghum, Sete Lagoas 35701-970, Brazil; email: jurandir.magalhaes@embrapa.br Annu. Rev. Plant Biol. 2015. 66:23.1–23.28 The Annual Review of Plant Biology is online at plant.annualreviews.org This article’s doi: 10.1146/annurev-arplant-043014-114822 Copyright c  2015 by Annual Reviews. All rights reserved Keywords aluminum resistance, aluminum tolerance, aluminum exclusion, root organic acid exudation, ALMT, MATE Abstract Aluminum (Al) toxicity in acid soils is a significant limitation to crop pro- duction worldwide, as approximately 50% of the world’s potentially arable soil is acidic. Because acid soils are such an important constraint to agricul- ture, understanding the mechanisms and genes conferring resistance to Al toxicity has been a focus of intense research interest in the decade since the last article on crop acid soil tolerance was published in this journal. An im- pressive amount of progress has been made during that time that has greatly increased our understanding of the diversity of Al resistance genes and mech- anisms, how resistance gene expression is regulated and triggered by Al and Al-induced signals, and how the proteins encoded by these genes function and are regulated. This review examines the state of our understanding of the physiological, genetic, and molecular bases for crop Al tolerance, looking at the novel Al resistance genes and mechanisms that have been identified over the past ten years. Additionally, it examines how the integration of molecular and genetic analyses of crop Al resistance is starting to be exploited for the improvement of crop plants grown on acid soils via both molecular-assisted breeding and biotechnology approaches. 23.1 Review in Advance first posted online on January 22, 2015. (Changes may still occur before final publication online and in print.) Changes may still occur before final publication online and in print Annu. Rev. Plant Biol. 2015.66. Downloaded from www.annualreviews.org Access provided by Cornell University on 02/03/15. For personal use only.