Aluminium reactions with polygalacturonate and related organic ligands

Aluminium (Al), in inorganic monomeric forms, has been recognised as a limiting factor for root growth in many acid soils. Plant tolerance to Al may be achieved by the detoxification (complexation) of Al by organic ligands present in the rhizosphere. The Al-complexing ability of seven organic ligand...

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Bibliographic Details
Published in:Plant and soil 1995-04, Vol.171 (1), p.41-45
Main Authors: Ostatek-Boczynski, Z. (Queensland Univ., Brisbane, Qld. (Australia). Dept. of Agriculture), Kerven, G.L, Blamey, F.P.C
Format: Article
Language:English
Subjects:
Acid soils
ACIDE ORGANIQUE
ACIDOS ORGANICOS
Agronomy. Soil science and plant productions
ALUMINIO
ALUMINIUM
Aluminum
Biological and medical sciences
Chemical, physicochemical, biochemical and biological properties
CITRATE
CITRATES
CITRATOS
DESINTOXICACION
DETOXIFICATION
FITOTOXICIDAD
Fundamental and applied biological sciences. Psychology
LIGAND
LIGANDOS
LIGANDS
Mineral components. Ionic and exchange properties
ORGANIC ACIDS
Organic soils
OXALATE
OXALATES
OXALATOS
PECTINAS
PECTINE
PECTINS
Physics, chemistry, biochemistry and biology of agricultural and forest soils
PHYTOTOXICITE
PHYTOTOXICITY
Plant roots
Plants
Root growth
Soil science
VIGNA RADIATA
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Summary:Aluminium (Al), in inorganic monomeric forms, has been recognised as a limiting factor for root growth in many acid soils. Plant tolerance to Al may be achieved by the detoxification (complexation) of Al by organic ligands present in the rhizosphere. The Al-complexing ability of seven organic ligands, citric, oxalic, gluconic, glucuronic, mucic, galacturonic and polygalacturonic (pectin) acids, was investigated. The proportion of organically-complexed Al was determined using colorimetrie methods based on differences in reaction rate with pyrocatechol violet or aluminon. The colorimetrie methods confirmed that citric acid forms a strong complex with Al at pH 4.2. In contrast, pectin and related organic ligands weakly complexed Al in acidic conditions. In an additional study, the Al-binding ability of pectin and Ca-pectate was compared at a biologically significant concentration of 32 µM Al. Only 29% of free Al remained in solution in the presence of Ca-pectate, while 54% remained when pectin was present. This suggests that Ca-pectate, rather than pectin, is responsible for binding Al in root cell walls and consequently plays an important role in Al toxicity to plants. Root growth of mungbean (Vigna radiata (L.) Wilczek) confirmed differences in the ability of citrate, oxalate and galacturonate to complex Al.
ISSN:0032-079X
1573-5036
DOI:10.1007/BF00009562