Metal insensitivity in ericoid mycorrhizal endophytes from Woollsia pungens (Epacridaceae)

Abstract

The influence of Cd²⁺, Cu²⁺ and Zn²⁺ on biomass production by 13 ericoid mycorrhizal endophytes (all putative Leotiales ascomycetes) from Woollsia pungens (Epacridaceae), along with three isolates of Hymenoscyphus spp., was investigated in axenic liquid culture. Inter- and intraspecific variation was observed in effective concentration values that inhibited growth by 50% (EC₅₀) for each metal; however, values varied by only a single order of magnitude for a particular metal (16.67–261.00 mmol m^–3 for Zn²⁺, 2.50–12.33 mmol m^–3 for Cd²⁺ and 3.00–43.88 mmol m^-3for Cu²⁺). Values of EC₅₀ for the endophytes from W. pungens were thus broadly similar to those from H. ericae. Combined metal treatments had either additive or ameliorative effects on the toxicity of individual metals to the various isolates. The data suggest that resistance to toxic metals is broadly similar in ericoid mycorrhizal endophytes from Northern Hemisphere Ericaceae and Australian Epacridaceae.