Phoma macrostoma; ITS sequencing provides confirmation of a unique genotype

Wayne Pitt, K.L. Bailey, Y.B., Fu, G.W. Peterson

Research output: Contribution to journalArticlepeer-review


The coelomycete fungus Phoma macrostoma Mont., originally isolated from diseased Canada thistle, is being assessed as a potential bioherbicide for control of dandelion, scentless chamomile, chickweed, and several other weedy broadleaf species. Tests for herbicidal activity on dandelion and specificity to a host-specific probe suggested that isolates obtained from Canada thistle and collected in Canada were unique. However, gross cultural characteristics in this genus are extremely variable, and the taxonomy of this species is unclear. To more accurately identify strains collected from Canada thistle, 48 isolates of P. macrostoma obtained from world collections were compared with 10 strains collected in Canada, with 32 isolates sequenced for the internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2). Alignment of ITS sequences revealed the presence of two large groups. Group I contained all the biocontrol strains from Canada thistle and indigenous to Canada, while Group II comprised numerous isolates from many hosts and localities. Group I and II isolates differed by a total of 20 bp (3.8% of the 524-bp region). Fungal isolates with herbicidal activity against broadleaf weeds are genotypically distinct from those obtained from other hosts and locations.
Original languageEnglish
Pages (from-to)168-168
Number of pages1
JournalCanadian Journal of Plant Pathology
Issue number1
Publication statusPublished - 2005


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