Submitted to: PLoS Pathogens
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/16/2013
Publication Date: 5/6/2013
Citation: Doyle, V.P., Oudemans, P.V., Rehner, S.A., Litt, A. 2013. Habitat and host indicate lineage identity in Colletotrichum gloeosporioides s.l. from wild and agricultural landscapes in North America. PLoS Pathogens. DOI: 10.1371/journal.pone.0062394. Interpretive Summary: Many fungi that cause disease in agricultural crop plants infect other plant species that also grow within or adjacent to agricultural areas. Fungi in the Colletotrichum gloeosporioides species complex cause fruit and stem diseases of cranberry in North America. To understand their diversity and host range, these fungi were sampled from cranberry plants as well as other plants that commonly grow in and around cranberry fields. A total of seven Colletotrichum species associated with cranberry were detected using DNA sequencing methods; three are described as new species. These new species cause fruit and stem diseases in cranberry and two were shown to also infect non-crop species that grow in cranberry bogs. Knowledge of these species will be useful to and should provide useful tools for plant breeders and plant pathologists in their efforts to develop resistant cultivars for an industry that utilizes one of North America’s few native crop species, the cranberry.
Technical Abstract: Understanding the factors that drive the evolution of pathogenic fungi is central to revealing the mechanisms of virulence and host preference, as well as developing effective disease control measures. Prerequisite to these pursuits is the accurate delimitation of species boundaries. Colletotrichum gloeosporioides s.l. is a species complex of plant pathogens and endophytic fungi for which reliable species recognition has only recently become possible through a multi-locus phylogenetic approach. By adopting an intensive regional sampling strategy encompassing multiple hosts within and beyond agricultural boundaries associated with commercial cranberry bogs, we have integrated North America strains of Colletotrichum gloeosporioides s.l. from these habitats into a broader phylogenetic framework. We delimit species on the basis of genealogical concordance phylogenetic species recognition (GCPSR) and quantitatively assess the monophyly of delimited species at each of four nuclear loci and in the combined data set with the genealogical sorting index (gsi). Our analysis resolved two principal lineages within the species complex. Strains isolated from cranberry (Vaccinium macrocarpon Aiton) and sympatric host plants are distributed across both of these lineages and belong to seven distinct species or terminal clades. Strains isolated from V. macrocarpon in commercial cranberry bogs belong to four species, three of which are described here as new, C. fructivorum sp. nov., C. temperatum sp. nov., and C. melanocaulon sp. nov. Another species, C. rhexiae, is epitypified. Intensive regional sampling has revealed a combination of factors, including the host species from which a strain has been isolated, the host organ of origin, and the habitat of the host species, as useful indicators of species identity. We have identified three broadly distributed temperate species, C. fructivorum, C. rhexiae, and C. nupharicola, which will be useful for understanding the microevolutionary forces that may lead to species divergence in this important genus of endophytes and plant pathogens.