title: Effect of aluminum on metabolism of organic acids and chemical forms of aluminum in root tips of Eucalyptus camaldulensis Dehnh.
abstract: Eucalyptus (Eucalyptus camaldulensis) has relatively high resistance to aluminum (Al) toxicity than the various herbaceous plants and model plant species. To investigate Al-tolerance mechanism, the metabolism of organic acids and the chemical forms of Al in the target site (root tips) in Eucalyptus was investigated. To do this, 2-year old rooted cuttings of E. camaldulensis were cultivated in half-strength Hoagland solution (pH 4.0) containing Al (0, 0.25, 0.5, 1.0, 2.5 and 5.0mM) salts for 5weeks; growth was not affected at concentrations up to 2.5mM even with Al concentration reaching 6000μgg(-1) DW. In roots, the citrate content also increased with increasing Al application. Concurrently, the activities of aconitase and NADP(+)-isocitrate dehydrogenase, which catalyze the decomposition of citrate, decreased. On the other hand, the activity of citrate synthase was not affected at concentrations up to 2.5mM Al. (27)Al-NMR spectroscopic analyses were carried out where it was found that Al-citrate complexes were a major chemical form present in cell sap of root tips. These findings suggested that E. camaldulensis detoxifies Al by forming Al-citrate complexes, and that this is achieved through Al-induced citrate accumulation in root tips via suppression of the citrate decomposition pathway.
authors.affiliation: Graduate School of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ikka
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ogawa
authors.forename: Donghua
authors.initials: D
authors.lastname: Li
authors.forename: Syuntaro
authors.initials: S
authors.lastname: Hiradate
authors.forename: Akio
authors.initials: A
authors.lastname: Morita
mesh_terms: D000154:Aconitate Hydratase / Q000378:metabolism; D000535:Aluminum / Q000737:chemistry / Q000494:pharmacology*; D001673:Biodegradation, Environmental / Q000187:drug effects; D002951:Citrates / Q000737:chemistry / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005052:Eucalyptus / Q000737:chemistry / Q000187:drug effects* / Q000254:growth & development; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D018519:Meristem / Q000737:chemistry / Q000187:drug effects / Q000254:growth & development; D009942:Organometallic Compounds / Q000737:chemistry / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000737:chemistry / Q000187:drug effects* / Q000254:growth & development
chemical_list: D002951:Citrates; D009942:Organometallic Compounds; D010940:Plant Proteins; D000535:Aluminum; D007521:Isocitrate Dehydrogenase; D000154:Aconitate Hydratase
keywords: (27)Al-NMR analysis; Aluminum tolerance; Al–citrate complex; Eucalyptus; Eucalyptus camaldulensis; Myctaceae; Organic acid metabolism