title: Roles of organic acid anion secretion in aluminium tolerance of higher plants.
abstract: Approximately 30% of the world's total land area and over 50% of the world's potential arable lands are acidic. Furthermore, the acidity of the soils is gradually increasing as a result of the environmental problems including some farming practices and acid rain. At mildly acidic or neutral soils, aluminium (Al) occurs primarily as insoluble deposits and is essentially biologically inactive. However, in many acidic soils throughout the tropics and subtropics, Al toxicity is a major factor limiting crop productivity. The Al-induced secretion of organic acid (OA) anions, mainly citrate, oxalate, and malate, from roots is the best documented mechanism of Al tolerance in higher plants. Increasing evidence shows that the Al-induced secretion of OA anions may be related to the following several factors, including (a) anion channels or transporters, (b) internal concentrations of OA anions in plant tissues, (d) temperature, (e) root plasma membrane (PM) H(+)-ATPase, (f) magnesium (Mg), and (e) phosphorus (P). Genetically modified plants and cells with higher Al tolerance by overexpressing genes for the secretion and the biosynthesis of OA anions have been obtained. In addition, some aspects needed to be further studied are also discussed.
authors.affiliation: Department of Agricultural Resources and Environmental Sciences, College of Resources and Environmental Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Lin-Tong
authors.initials: LT
authors.lastname: Yang
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Qi
authors.forename: Huan-Xin
authors.initials: HX
authors.lastname: Jiang
authors.forename: Li-Song
authors.initials: LS
authors.lastname: Chen
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000535:Aluminum / Q000494:pharmacology*; D000838:Anions; D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D019343:Citric Acid / Q000378:metabolism*; D018556:Crops, Agricultural / Q000187:drug effects / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008274:Magnesium / Q000378:metabolism; D008293:Malates / Q000378:metabolism*; D009599:Nitroprusside / Q000494:pharmacology; D019815:Oxalic Acid / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology; D010944:Plants / Q000187:drug effects / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000378:metabolism; D013696:Temperature; D014026:Nicotiana / Q000187:drug effects / Q000378:metabolism
chemical_list: D000838:Anions; D008293:Malates; D010940:Plant Proteins; D009599:Nitroprusside; D010758:Phosphorus; D019343:Citric Acid; C030298:malic acid; D019815:Oxalic Acid; D000535:Aluminum; D000251:Adenosine Triphosphatases; D008274:Magnesium