ALUMINUM POLYPHOSPHATE COMPLEXES IN THE MYCORRHIZAL BASIDIOMYCETE LACCARIA BICOLOR - A AL-27 NUCLEAR-MAGNETIC-RESONANCE STUDY

The techniques of Al-27- and P-31-nuclear magnetic resonance (NMR) spe ctroscopy were used to investigate the interactions of aluminium with intracellular ligands within the mycelium of the ectomycorrhizal basid iomycete Laccaria bicolor (Maire) Orton (S238). The vegetative myceliu m was grown on medium containing 0.5 mM AlCl3 for 0.5 to 3 d. The Al-2 7-NMR spectra showed that aluminium was rapidly taken up and accumulat ed into polyphosphate complexes in the vacuole. Comparison with Al-pol yphosphate complexes obtained in vitro on model systems indicated that Al forms at least three mixed-solvation complexes with Pi and polypho sphates, that there is more than one complex present under any set of conditions, and that the equilibrium between these complexes shifts dr amatically with Al concentration in the medium. The high phosphate con centrations in the growth medium favoured the accumulation of the Al-p olyphosphate complexes was transferred to al-free nutrient solution fo r 9 d, the Al-polyphosphate complexes were not remobilized. The seques tration of Al in the polyphosphate complexes could therefore make a si gnificant contribution to the protection of mycorrhizal plants against aluminium toxicity.