Allelopathic effects of Cladonia cristatella on ectomycorrhizal fungi common to bituminous strip-mine spoils

Abstract

Acetone–toluene extracts of Cladonia cristatella inhibited the growth of fungi known to form ectomycorrhizal associations with trees commonly found on bituminous strip-mine spoils in western Pennsylvania. Growth of Pisolithus tinctorius and Suillus luteus was completely inhibited by C. cristatella extracts over a 30-d bioassay period. Thelephora terrestris was dead after 17 d. The growth of Cenococcum graniforme was unaffected by lichen extracts. D-Usnic acid, a major secondary compound of the C. cristatella extract, was found to inhibit the growth of P. tinctorius. This inhibition, however, did not account for the total inhibition of P. tinctorius demonstrated by the gross acetone–toluene extract. Other secondary compounds, and potential allelopathic substances, present in the extract were barbatic acid, didymic acid, condidymic acid, subdidymic acid, fumarprotocetraric acid, squamatic acid, and rhodocladonic acid.