ARS | Publication request: Population Structure of the North American Cranberry Fruit Rot Complex

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 2, 2007
Publication Date: N/A

Technical Abstract: Cranberry fruit rot is caused by a complex of pathogenic fungi. Variation in the populations within this complex from region to region could delay identification of the causal agents(s) and complicate management strategies. Our objective was to assess genetic variation within the four major fruit rot pathogens (Phyllosticta vaccinii, Coleophoma empetri, Colletotrichum acutatum, and Physalospora vaccinii). Representative isolates of each species were collected from NJ, MA, WI, and British Columbia (BC). Species availability varied by region. For example, Phyllosticta vaccinii was rare in WI and BC, but common in NJ and MA. We hypothesized that genetic variation would be low in the pathogens with a limited host range, while those with a broad host range would be more variable. ITS sequence data showed that variation (98-100% nucleotide similarity) was less than expected in the broad host range C. acutatum, but as anticipated in the narrow host range Phyllosticta vaccinii. In contrast, C. empetri split into two distinct clades. Clade association was not correlated with site of origin, and the representatives in each clade were morphologically indistinguishable. Physalospora ITS sequencing and probe development for rapid detection of all species is in progress. Studies are also planned to determine if C. empetri from cranberry is composed of more than one species.