Affiliation:
1. Goethe-Universität Frankfurt am Main, Department of Biological Sciences, Institute of Ecology, Evolution and Diversity, Max-von-Laue Str. 13, D-60438 Frankfurt am Main, Germany; Senckenberg Biodiversity and Climate Research Centre, Senckenberganlage
25, D-60325 Frankfurt am Main, Germany
Abstract
The genus Ducellieria (Ducellieriaceae) contains three species (D. chodatii, D. tricuspidata, D. corcontica), and a single variety ( D. chodatii var. armata ) of obligate endobiotic pollen parasites. These organisms have been first assigned to the
green alga genus Coelastrum, as they form very similar spherical structures, but the observation of heterokont zoospores has led to their reclassification to the phylum Oomycota. However, despite their widespread nature, these organisms are only known from their descriptive morphology,
and life cycle traits of some species still remain incompletely known. Only the type species, D. chodatii, has been rediscovered several times, but the phylogeny of the genus remains unresolved, since none of its species has been studied for their molecular phylogeny. At present the
genus is still included in some algal databases. To clarify the evolutionary affiliation of Ducellieria, efforts were undertaken to isolate D. chodatii from pollen grains, to infer its phylogenetic placement based on nrSSU sequences. By targeted isolation, the pollen endoparasitoid
was rediscovered from three lakes in Germany (Mummelsee, Okertalsperre, Knappensee). Apart from the typical coelastrum-like spheroids, oomycetes sporulating directly from pollen grains in a lagenidium-like fashion were observed, and molecular sequences of both types of oomycetes were obtained.
Phylogenetic reconstruction revealed that coelastrum-like and lagenidium-like forms are unrelated, with the former embedded within the deep branching early-diverging lineages, and the later stage forming a distinct clade in Peronosporales. Consequently, the life cycle of D. chodatii
needs careful revision using single-spore isolates of the species, to infer if previous lifecycle reconstructions that involve various different thallus types are stages of a single species or potentially of several ones.
Publisher
Westerdijk Fungal Biodiversity Institute
Subject
Agricultural and Biological Sciences (miscellaneous),Biochemistry, Genetics and Molecular Biology (miscellaneous),Ecology, Evolution, Behavior and Systematics,Microbiology
Cited by
1 articles.
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