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Molecular phylogenetic diversity, multilocus haplotype nomenclature, and in vitro antifungal resistance within the Fusarium solani species complex.

ABSTRACT: Members of the species-rich Fusarium solani species complex (FSSC) are responsible for approximately two-thirds all fusarioses of humans and other animals. In addition, many economically important phytopathogenic species are nested within this complex. Due to their increasing clinical relevance and because most of the human pathogenic and plant pathogenic FSSC lack Latin binomials, we have extended the multilocus haplotype nomenclatural system introduced in a previous study (D. C. Chang, G. B. Grant, K. O'Donnell, K. A. Wannemuehler, J. Noble-Wang, C. Y. Rao, L. M. Jacobson, C. S. Crowell, R. S. Sneed, F. M. T. Lewis, J. K. Schaffzin, M. A. Kainer, C. A. Genese, E. C. Alfonso, D. B. Jones, A. Srinivasan, S. K. Fridkin, and B. J. Park, JAMA 296:953-963, 2006) to all 34 species within the medically important FSSC clade 3 to facilitate global epidemiological studies. The typing scheme is based on polymorphisms in portions of the following three genes: the internal transcribed spacer region and domains D1 plus D2 of the nuclear large-subunit rRNA, the translation elongation factor 1 alpha gene (EF-1alpha), and the second largest subunit of RNA polymerase II gene (RPB2). Of the 251 isolates subjected to multilocus DNA sequence typing, 191 sequence types were differentiated, and these were distributed among three strongly supported clades designated 1, 2, and 3. All of the mycosis-associated isolates were restricted to FSSC clade 3, as previously reported (N. Zhang, K. O'Donnell, D. A. Sutton, F. A Nalim, R. C. Summerbell, A. A. Padhye, and D. M. Geiser, J. Clin. Microbiol. 44:2186-2190, 2006), and these represent at least 20 phylogenetically distinct species. Analyses of the combined DNA sequence data by use of two separate phylogenetic methods yielded the most robust hypothesis of evolutionary relationships and genetic diversity within the FSSC to date. The in vitro activities of 10 antifungals tested against 19 isolates representing 18 species that span the breadth of the FSSC phylogeny show that members of this complex are broadly resistant to these drugs.

SUBMITTER: O'Donnell K

PROVIDER: S-EPMC2519483 | biostudies-literature | 2008 Aug

REPOSITORIES: biostudies-literature

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Molecular phylogenetic diversity, multilocus haplotype nomenclature, and in vitro antifungal resistance within the Fusarium solani species complex.

O'Donnell Kerry K Sutton Deanna A DA Fothergill Annette A McCarthy Dora D Rinaldi Michael G MG Brandt Mary E ME Zhang Ning N Geiser David M DM

Journal of clinical microbiology 20080604 8

Members of the species-rich Fusarium solani species complex (FSSC) are responsible for approximately two-thirds all fusarioses of humans and other animals. In addition, many economically important phytopathogenic species are nested within this complex. Due to their increasing clinical relevance and because most of the human pathogenic and plant pathogenic FSSC lack Latin binomials, we have extended the multilocus haplotype nomenclatural system introduced in a previous study (D. C. Chang, G. B. G ...[more]

PMID: 18524963

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Project description:The Fusarium sambucinum species complex (FSAMSC) is one of the most taxonomically challenging groups of fusaria, comprising prominent mycotoxigenic plant pathogens and other species with various lifestyles. Among toxins produced by members of the FSAMSC, trichothecenes pose the most significant threat to public health. Herein a global collection of 171 strains, originating from diverse hosts or substrates, were selected to represent FSAMSC diversity. This strain collection was used to assess their species diversity, evaluate their potential to produce trichothecenes, and cause disease on wheat. Maximum likelihood and Bayesian analyses of a combined 3-gene dataset used to infer evolutionary relationships revealed that the 171 strains originally received as 48 species represent 74 genealogically exclusive phylogenetically distinct species distributed among six strongly supported clades: Brachygibbosum, Graminearum, Longipes, Novel, Sambucinum, and Sporotrichioides. Most of the strains produced trichothecenes in vitro but varied in type, indicating that the six clades correspond to type A, type B, or both types of trichothecene-producing lineages. Furthermore, five strains representing two putative novel species within the Sambucinum Clade produced two newly discovered type A trichothecenes, 15-keto NX-2 and 15-keto NX-3. Strains of the two putatively novel species together with members of the Graminearum Clade were aggressive toward wheat when tested for pathogenicity on heads of the susceptible cultivar Apogee. In planta, the Graminearum Clade strains produced nivalenol or deoxynivalenol and the aggressive Sambucinum Clade strains synthesized NX-3 and 15-keto NX-3. Other strains within the Brachygibbosum, Longipes, Novel, Sambucinum, and Sporotrichioides Clades were nonpathogenic or could infect the inoculated floret without spreading within the head. Moreover, most of these strains did not produce any toxin in the inoculated spikelets. These data highlight aggressiveness toward wheat appears to be influenced by the type of toxin produced and that it is not limited to members of the Graminearum Clade.

Project description:Culture-independent analysis of the gut of a wood-boring insect, Anoplophora glabripennis (Coleoptera: Cerambycidae), revealed a consistent association between members of the fungal Fusarium solani species complex and the larval stage of both colony-derived and wild A. glabripennis populations. Using the translation elongation factor 1-alpha region for culture-independent phylogenetic and operational taxonomic unit (OTU)-based analyses, only two OTUs were detected, suggesting that genetic variance at this locus was low among A. glabripennis-associated isolates. To better survey the genetic variation of F. solani associated with A. glabripennis, and establish its phylogenetic relationship with other members of the F. solani species complex, single spore isolates were created from different populations and multi-locus phylogenetic analysis was performed using a combination of the translation elongation factor alpha-1, internal transcribed spacer, and large subunit rDNA regions. These analyses revealed that colony-derived larvae reared in three different tree species or on artificial diet, as well as larvae from wild populations collected from three additional tree species in New York City and from a single tree species in Worcester, MA, consistently harbored F. solani within their guts. While there is some genetic variation in the F. solani carried between populations, within-population variation is low. We speculate that F. solani is able to fill a broad niche in the A. glabripennis gut, providing it with fungal lignocellulases to allow the larvae to grow and develop on woody tissue. However, it is likely that many F. solani genotypes could potentially fill this niche, so the relationship may not be limited to a single member of the F. solani species complex. While little is known about the role of filamentous fungi and their symbiotic associations with insects, this report suggests that larval A. glabripennis has developed an intimate relationship with F. solani that is not limited by geographic location or host tree.

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Dataset Information

Molecular phylogenetic diversity, multilocus haplotype nomenclature, and in vitro antifungal resistance within the Fusarium solani species complex.

Publications

Molecular phylogenetic diversity, multilocus haplotype nomenclature, and in vitro antifungal resistance within the Fusarium solani species complex.

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