Isolation, characterization, and avenacin sensitivity of a diverse collection of cereal-root-colonizing fungi

A total of 161 fungal isolates were obtained from the surface-sterilized ro ots of field-grown oat and wheat plants in order to investigate the nature of the root-colonizing fungi supported by these two cereals. Fungi were ini tially grouped according to their colony morphologies and then were further characterized by ribosomal DNA sequence analysis. The collection contained a wide range of ascomycetes and also some basidiomycete fungi. The fungi w ere subsequently assessed for their abilities to tolerate and degrade the a ntifungal oat root saponin, avenacin A-1. Nearly all the fungi obtained fro m oat roots were avenacin A-1 resistant, while both avenacin-sensitive and avenacin-resistant fungi were isolated from the roots of the non-saponin-pr oducing cereal, wheat. The majority of the avenacin-resistant fungi were ab le to degrade avenacin A-1. These experiments suggest that avenacin A-1 is likely to influence the development of fungal communities within (and possi bly also around) oat roots.