In vitro antagonism of edible ectomycorrhizal fungi against Fusarium oxysporum and Fusarium verticillioides

Abstract

Twenty-one isolates of edible ectomycorrhizal fungi (ECM) of 15 different species were tested in vitro for mycelial growth and spore germination against two isolates each of Fusarium oxysporum and F. verticillioides. The growth of Fusarium isolates was significantly inhibited when co-cultured with most of the 21 ECM fungi tested. Two ECM fungi (Ba-2 and Xf-2) failed to reduce the growth of Fusariumisolates. In paired cultures, growth of all Fusariumisolates was significantly reduced by Rhizopogon roseolus, Suillus luteus, Tricholoma portentosum, Amanita rubescens, Amanita ovoidea, Boletus fragrans and Laccaria laccata. Spore germination of all Fusariumisolates was strongly inhibited by culture filtrates of R. roseolus and the two S. luteus isolates. Different behavior between ectomycorrhizal fungi and Fusarium species, as well as among isolates of the same species was observed in both assays. Inhibition of Fusarium species suggests that several isolates of edible ectomycorrhizal fungi have a high potential for biological control of damping off. The effect of ECM fungi was less evident in the conidial germination assay than in the growth assay, although inhibition was also observed. The methodology presented here can be used as an effective tool for in vitro selection of ectomycorrhizal fungi and in nursery assays.