Distribution and chemical speciation of
aluminum in the Al accumulator plant, Melastoma malabathricum L.
Watanabe T, Osaki M, Yoshihara T, Tadano T
PLANT AND SOIL 201 (2): 165-173 APR 1998
Abstract: The Al accumulation mechanisms in
an Al accumulator plant, Melastoma malabathricum L. (Melastoma), was
investigated. Al was located in the upper epidermal cells and also distributed
in mesophyll cells in leaf sections. In root sections, Al was found in all the
root tissues, particularly in the epidermis and endodermis. Al concentrations
in young leaves, mature leaves, old leaves, and roots were 8.0, 9.2, 14.4, and
10.1 mg g-1, respectively. Approximately 45% of total Al in oldest
leaves, and approximately 60% of total Al in leaves of other positions and
roots were extracted in Tris-HCl buffer (pH 7.0). Since Al in the residual
parts was mostly dissolved in hot 0.5 M H2SO4 containing
2% cetyl trimethylammonium bromide, residual Al seemed to consist mainly of
monomeric Al and Al bound to pectic substances and hemicellulose. Al in the
Tris-HCl extract consisted of non-monomeric Al (complexed form). Oxalate
concentration in the Tris-HCl extract in leaves was significantly higher in the
+Al treatment than in the -Al treatment and there was a positive correlation
between the Al concentration and oxalate concentration. Al27-NMR
spectrum of fresh leaves indicated the presence in the order of monomeric Al,
Al-oxalate, Al-(oxalate)2, and Al-(oxalate)3 in intact
leaves.
Keywords: Al accumulator plant; Al distribution; Al localization; Al-oxalate complex; Melastoma malabathricum L; Al27-NMR