Phosphate-solubilising abilities of ericoid mycorrhizal endophytes of Woollsia pungens (Epacridaceae)

The ability of 13 mycorrhizal endophytes from Woollsia pungens (Cav.) F.Muell. (Epacridaceae) and three Hymenoscyphus isolates to solubilise hydroxyapatite and fluorapatite was assessed in axenic culture under a range of conditions. All Hymenoscyphus isolates and most of the endophytes from W. pungens solubilised hydroxyapatite in unbuffered media containing NH4+ as the sole nitrogen source, but were unable to solubilise this substrate in buffered media or when NO3- was the sole nitrogen source. None of the isolates solubilised fluorapatite under any of the conditions tested. The internal phosphorus status of the mycelia had no influence on the ability of the isolates to solubilise either substrate. The data suggest that the phosphate-solubilising activities of mycorrhizal endophytes of Epacridaceae in soil may be confined to the less chemically resistant phosphorus sources.