Asking probing questions: Can fluorescent in situ hybridization identify and localise aquatic hyphomycetes on leaf litter?

Based on partial sequences of 16S rRNA of 8 strains of the nectrioid group, a fluorescently labeled oligonucleotide was designed for in situ hybridiza tion. It reacted with mycelia of 4 Heliscus lugdunensis strains, but not wi th mycelia of Cylindrocarpon destructans, Flagellospora curta, F. curvula, or Fusarium aquaeductuum. Much weaker signals were found with conidia. Stai ning with Rhodamine 123 showed that mitochondria in conidia were intact. Wh en fungal mycelia were observed on alder or maple leaves, the specificity o f the probe was maintained, but there was some interference due to autofluo rescence of leaf parts and algal pigments.