Inorganic and organic substrates as sources of nitrogen and phosphorus for multiple genotypes of two ericoid mycorrhizal fungal taxa from Woollsia pungens and Leucopogon parviflorus (Ericaceae)

Abstract

The abilities of six genotypes of two putative Helotiales ascomycete ericoid mycorrhizal fungal taxa from Woollsia pungens Cav. (Muell.) and Leucopogon parviflorus (Andr.) Lindl. (Ericaceae) to utilise a range of nitrogen and phosphorus compounds for growth were tested in axenic liquid culture. Although significant intra- and interspecific variation was observed, genotypes of both taxa utilised NH₄⁺, NO₃^–, a range of acidic, neutral and basic amino acids and bovine serum albumen as sole nitrogen sources, along with orthophosphate, inositol hexaphosphate and DNA as sole phosphorus sources. For several isolates of each taxon, growth on the sulfur-containing amino acid cysteine was increased significantly when other forms of sulfur were excluded from the growth medium, suggesting that cysteine utilisation may represent a sulfur-scavenging strategy. Pooled data for all genotypes indicated that Taxon II produced significantly greater biomass on most substrates; however, in no case did this differ by an order of magnitude or more. Both taxa thus appear likely to have broadly similar abilities to obtain nitrogen and phosphorus from organic substrates on soil.