title: Aluminium alleviates manganese toxicity to rice by decreasing root symplastic Mn uptake and reducing availability to shoots of Mn stored in roots.
abstract: OBJECTIVE
  Manganese (Mn) and aluminium (Al) phytotoxicities occur mainly in acid soils. In some plant species, Al alleviates Mn toxicity, but the mechanisms underlying this effect are obscure.
  
  
  METHODS
  Rice (Oryza sativa) seedlings (11 d old) were grown in nutrient solution containing different concentrations of Mn(2+) and Al(3+) in short-term (24 h) and long-term (3 weeks) treatments. Measurements were taken of root symplastic sap, root Mn plaques, cell membrane electrical surface potential and Mn activity, root morphology and plant growth.
  
  
  RESULTS
  In the 3-week treatment, addition of Al resulted in increased root and shoot dry weight for plants under toxic levels of Mn. This was associated with decreased Mn concentration in the shoots and increased Mn concentration in the roots. In the 24-h treatment, addition of Al resulted in decreased Mn accumulation in the root symplasts and in the shoots. This was attributed to higher cell membrane surface electrical potential and lower Mn(2+) activity at the cell membrane surface. The increased Mn accumulation in roots from the 3-week treatment was attributed to the formation of Mn plaques, which were probably related to the Al-induced increase in root aerenchyma.
  
  
  CONCLUSIONS
  The results show that Al alleviated Mn toxicity in rice, and this could be attributed to decreased shoot Mn accumulation resulting from an Al-induced decrease in root symplastic Mn uptake. The decrease in root symplastic Mn uptake resulted from an Al-induced change in cell membrane potential. In addition, Al increased Mn plaques in the roots and changed the binding properties of the cell wall, resulting in accumulation of non-available Mn in roots.
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China and University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China and.
authors.forename: Xue Qiang
authors.initials: XQ
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China and University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Zhen Min
authors.initials: ZM
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China and University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Ji Feng
authors.initials: JF
authors.lastname: Shao
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China and University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Che
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China and.
authors.forename: Rong Fu
authors.initials: RF
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China and.
authors.forename: Xiao Ying
authors.initials: XY
authors.lastname: Dong
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China and rfshen@issas.ac.cn.
authors.forename: Ren Fang
authors.initials: RF
authors.lastname: Shen
mesh_terms: D000535:Aluminum / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D008345:Manganese / Q000378:metabolism* / Q000633:toxicity*; D008564:Membrane Potentials / Q000187:drug effects; D012275:Oryza / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D010936:Plant Extracts / Q000737:chemistry; D018517:Plant Roots / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism*; D018520:Plant Shoots / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism*; D012996:Solutions; D013052:Spectrometry, X-Ray Emission
chemical_list: D010936:Plant Extracts; D012996:Solutions; D008345:Manganese; D000535:Aluminum
keywords: Aluminium; Gouy–Chapman–Stern model; Oryza sativa; acid soils.; manganese plaques; manganese toxicity; plasma membrane surface electrical potential; rice; root aerenchyma; root symplast