INHIBITION OF SELECTED HYPOCREALEAN FUNGI BY LICHEN SECONDARY METABOLITES

Isolates of four hypocrealean fungi were used in laboratory experiment s designed to determine their ability to degrade lichen tissues and th e extent to which lichen secondary metabolites inhibit this degradatio n. Two fungi (Nectria parmeliae and Pronectria oligospora) were origin ally isolated from lichens and two (Nectriopsis squamulosa and Nectria zonata) were isolated from nonlichen substrates. A series of growth e xperiments was done on five test lichens: Flavoparmelia baltimorensis, Xanthoparmelia conspersa, Punctelia rudecta, Myelochroa aurulenta, an d Lasallia papulosa. These lichen species were chosen based on previou s experiments with the lichenicolous hyphomycete Hobsonia christiansen ii, which appeared to make host preferences among these lichens based on secondary chemistry. Results of our experiments demonstrated that t he two nonlichenicolous fungi (N. squamulosa and N. zonata) were gener ally unable to degrade lichens, even in the absence of lichen secondar y metabolites. As expected, the lichenicolous fungi (N. parmeliae and P. oligospora) readily degraded lichen tissues; however, each made res ponses to the presence of lichen secondary metabolites indicating a po tential inhibitory role for these compounds.