title: Organic acid anions: An effective defensive weapon for plants against aluminum toxicity and phosphorus deficiency in acidic soils.
abstract: Aluminum (Al) toxicity and phosphorous (P) deficiency are two major limiting factors for plant growth on acidic soils. Thus, the physiological mechanisms for Al tolerance and P acquisition have been intensively studied. A commonly observed trait is that plants have developed the ability to utilize organic acid anions (OAs; mainly malate, citrate and oxalate) to combat Al toxicity and P deficiency. OAs secreted by roots into the rhizosphere can externally chelate Al3+and mobilize phosphate (Pi), while OAs synthesized in the cell can internally sequester Al3+into the vacuole and release free Pi for metabolism. Molecular mechanisms involved in OA synthesis and transport have been described in detail. Ensuing genetic improvement for Al tolerance and P efficiency through increased OA exudation and/or synthesis in crops has been achieved by transgenic and marker-assisted breeding. This review mainly elucidates the crucial roles of OAs in plant Al tolerance and P efficiency through summarizing associated physiological mechanisms, molecular traits and genetic manipulation of crops.
authors.affiliation: Root Biology Center, Fujian Agriculture and Forestry University, Fujian, Fuzhou 350002, China.
authors.forename: Zhi Chang
authors.initials: ZC
authors.lastname: Chen
authors.affiliation: Root Biology Center, Fujian Agriculture and Forestry University, Fujian, Fuzhou 350002, China. Electronic address: hliao@fafu.edu.cn.
authors.forename: Hong
authors.initials: H
authors.lastname: Liao
mesh_terms: D000535:Aluminum / Q000633:toxicity*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D009930:Organic Chemicals / Q000378:metabolism*; D010758:Phosphorus / Q000032:analysis* / Q000378:metabolism; D010944:Plants / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*
chemical_list: D009930:Organic Chemicals; D012987:Soil; D010758:Phosphorus; D000535:Aluminum
keywords: Acidic soils; Al toxicity; Organic acid anions; P deficiency