DEMONSTRATION OF A SHORT-CHAIN POLYPHOSPHATE IN PISOLITHUS-TINCTORIUS AND THE IMPLICATIONS FOR PHOSPHORUS TRANSPORT

Polyphosphate was extracted from an Australian isolate of Pisolithus tinctorius (Pers.) Coker and Couch, known to be mycorrhizal with Eucalyptus pilularis. It was separated from RNA and characterized by PAGE and P-31 NMR spectroscopy. A broad pink band, which showed gamma-metachromasy with toluidine blue, ran faster on acrylamide gels than a number of purple-blue bands (various RNA fractions) and did not stain with ethidium bromide, was identified as polyphosphate. The major pink band co-migrated with a synthetic polyphosphate standard of a chain length of about 15 phosphate (P-i) subunits, and analysis by P-31 nuclear magnetic resonance (NMR) spectroscopy confirmed that polyphosphate was a major fraction in the extract. Polyphosphate was extracted from mycelium grown at both high and low levels of P-i, but the amount extracted from cultures grown with 10 mM P-i (added as ammonium phosphate) was significantly greater. Polyphosphate was a substantial fraction of the phosphorus present in the hyphae and it is proposed that polyphosphate is transported along the hyphae by the motile tubule and vacuole system present in this fungus.