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Sexual Development and Ascospore Discharge in Fusarium graminearum
Published on: March 29, 2012
Cryptic speciation in Fusarium subglutinans.
Emma T Steenkamp1, Brenda D Wingfield, Anne E Desjardins
1Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002, South Africa.
Mycologia
|December 16, 2010
Summary
Phylogenetic analysis reveals cryptic species within Fusarium subglutinans, indicating divergence into distinct taxa. These findings challenge current Fusarium taxonomy and highlight ongoing speciation in this fungal complex.
Area of Science:
- Mycology
- Plant Pathology
- Evolutionary Biology
Background:
- Taxonomic classification of Fusarium species within the Gibberella fujikuroi complex relies on morphological, biological, and phylogenetic concepts.
- Morphological and biological species concepts present challenges in Fusarium taxonomy, with phylogenetic approaches offering more consistent identifications.
- Recent studies show discordance between biological and phylogenetic species concepts, particularly within Fusarium subglutinans (mating population E).
Purpose of the Study:
- To investigate whether the observed subdivision within Fusarium subglutinans sensu stricto represents true species divergence or intraspecific diversity.
- To clarify the taxonomic status of Fusarium subglutinans mating population E isolates.
- To contribute to a more accurate understanding of Fusarium species complexes.
Main Methods:
- Phylogenetic concordance analyses were performed on DNA sequence data from six nuclear regions.
- Twenty-nine Fusarium subglutinans isolates from mating population E, collected from maize and teosinte across a wide geographic range, were analyzed.
- Isolates were subjected to molecular phylogenetic analysis to assess genetic relationships.
Main Results:
- Phylogenetic analyses revealed two major distinct groups within the studied Fusarium subglutinans isolates, indicative of cryptic species.
- These cryptic species were further resolved into smaller, reproductively isolated groups, suggesting ongoing speciation.
- The observed divergences were not correlated with geographic origin, host plant (maize or teosinte), or observable phenotypic traits.
Conclusions:
- Fusarium subglutinans populations are undergoing divergence, leading to the formation of distinct cryptic species.
- These findings suggest that lineages within F. subglutinans are actively separating into new taxa.
- The study underscores the complexity of Fusarium taxonomy and the utility of phylogenetic methods in resolving cryptic diversity.
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