REFINEMENT OF PCR-DETECTION OF FUSARIUM-AVENACEUM AND EVIDENCE FROM DNA MARKER STUDIES FOR PHENETIC RELATEDNESS TO FUSARIUM-TRICINCTUM

Existing PCR-based assays for the detection of the cereal pathogen Fus arium avenaceum were found to cross-react with F. tricinctum. An inves tigation into the phenetic relationship between these two species usin g two different marker systems revealed a close relationship between t hem despite their being from separate taxonomic sections. Whilst RFLP differences in the ITS regions surrounding the nuclear 5.8 S rDNA were insufficient to discriminate between isolates of the two species, the y were clearly differentiated by RAPD profiling. RAPD fragments from E avenaceum isolates were screened for hybridization to F, tricinctum D NA on Southern blots. One of 12 selected RAPD fragments showed no hybr idization to genomic DNA from F. tricinctum. This fragment was cloned and sequenced, and the sequence obtained was used to design PCR primer s. The primers were found to be specific for F. avenaceum, with no cro ss-reactions obtained with F. tricinctum or any other wheat pathogen a ssayed. The primers were able to differentiate between the two species in infected plant material, in contrast to the earlier assays.