title: Form of aluminium for uptake and translocation in buckwheat (Fagopyrum esculentum Moench).
abstract: The forms of Al for uptake by the roots and translocation from the root to the shoot were investigated in a buckwheat (Fagopyrum esculentum Moench, cv. Jianxi) that accumulates Al in its leaves. The Al concentration in the xylem sap was 15-fold higher in the plants exposed to AlCl3 than in those exposed to an Al-oxalate (1:3) complex, suggesting that the roots take up Al in the ionic form. The Al concentration in the xylem sap was 4-fold higher than that in the external solution after a 1-h exposure to AICl3 solution and 10-fold higher after a 2-h exposure. The Al concentration in the xylem sap increased with increasing Al concentration in the external solution. The Al uptake was not affected by a respiratory inhibitor, hydroxylamine, but significantly inhibited by the addition of La. These results suggest that Al uptake by the root is a passive process, and La3+ competes for the binding sites for Al3+ on the plasma membrane. The form of Al in the xylem sap was identified by 27Al-nuclear magnetic resonance analysis. The chemical shift of 27Al in the xylem sap was around 10.9 ppm, which is consistent with that of the Al-citrate complex. Furthermore, the dominant organic acid in the xylem sap was citric acid, indicating that Al was translocated in the form of Al-citrate complex. Because Al is present as Al-oxalate (1:3) in the root, the present data show that ligand exchange from oxalate to citrate occurs before Al is released to xylem.
authors.affiliation: Faculty of Agriculture, Kagawa University, Kita-gun, Japan. maj@ag.kagawa-u.ac.jp
authors.forename: J F
authors.initials: JF
authors.lastname: Ma
authors.forename: S
authors.initials: S
authors.lastname: Hiradate
mesh_terms: D000535:Aluminum / Q000493:pharmacokinetics*; D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000493:pharmacokinetics; D001692:Biological Transport / Q000187:drug effects; D002712:Chlorides / Q000493:pharmacokinetics; D019612:Fagopyrum / Q000378:metabolism*; D019811:Hydroxylamine / Q000494:pharmacology; D007700:Kinetics; D007811:Lanthanum / Q000494:pharmacology; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D017607:Aluminum Compounds; D002712:Chlorides; D019811:Hydroxylamine; D000077410:Aluminum Chloride; D007811:Lanthanum; D000535:Aluminum