Abstract
Currently, the monophyletic lineage of anther smuts on Caryophyllaceae includes 22 species classified in the genus Microbotryum. They are model organisms studied in many disciplines of fungal biology. A molecular phylogenetic approach was used to resolve species boundaries within the caryophyllaceous anther smuts, as species delimitation based solely on phenotypic characters was problematic. Several cryptic species were found amongst the anther smuts on Caryophyllaceae, although some morphologically distinct species were discernible, and most species were characterized by high host-specificity. In this study, anther smut specimens infecting Silene saxifraga were analysed using rDNA sequences (ITS and LSU) and morphology to resolve their specific status and to discuss their phylogenetic position within the lineage of caryophyllaceous anther smuts. The molecular phylogeny revealed that all specimens form a monophyletic lineage that is supported by the morphological trait of reticulate spores with tuberculate interspaces (observed in certain spores). This lineage cannot be attributed to any of the previously described species, and the anther smut on Silene saxifraga is described and illustrated here as a new species, Microbotryum silenes-saxifragae. This species clusters in a clade that includes Microbotryum species, which infect both closely and distantly related host plants growing in diverse ecological habitats. It appears possible that host shifts combined with changes to ecological host niches drove the evolution of Microbotryum species within this clade.
Highlights
Plant parasitic fungi sporulating in the anthers of their hosts evolved independently in several genera/species of two major phylogenetic basidiomycetous lineages, including the pucciniomycotinous genera Bauerago (Vánky 1999, 2012) and Microbotryum (Vánky 1998, 2012, Kemler et al 2006, 2009), and the ustilaginomycotinous genera Antherospora (Bauer et al 2008, Piątek et al 2011, 2013), Thecaphora (Roets et al 2008, 2012, Vánky & Lutz 2007) and Urocystis (Vánky 2012)
The present study aims to resolve the specific status of the anther smut on Silene saxifraga using molecular phylogenetic analyses of concatenated ITS + LSU rDNA sequences as well as light and scanning electron microscope examination of specimens from several populations
Silene saxifraga is widely distributed on rocks and screes in southern European mountains, extending northwards to West Austria (Tutin et al 1993)
Summary
Plant parasitic fungi sporulating in the anthers of their hosts evolved independently in several genera/species of two major phylogenetic basidiomycetous lineages, including the pucciniomycotinous genera Bauerago (Vánky 1999, 2012) and Microbotryum (Vánky 1998, 2012, Kemler et al 2006, 2009), and the ustilaginomycotinous genera Antherospora (Bauer et al 2008, Piątek et al 2011, 2013), Thecaphora (Roets et al 2008, 2012, Vánky & Lutz 2007) and Urocystis (Vánky 2012). The anther smuts of Caryophyllaceae, commonly referred to as the Microbotryum violaceum complex, form a monophyletic lineage within the genus Microbotryum They are model organisms studied in many disciplines of fungal biology, for example, ecology (Thrall et al 1993), genomics (Hood 2005, Yockteng et al 2007), population studies (Lee 1981, Alexander & Antonovics 1995, Alexander et al 1996), life cycle studies (Schäfer et al 2010), geographic distribution (Hood et al 2010, Fontaine et al 2013), phylogeography (Vercken et al 2010), evolutionary history (López-Villavicencio et al 2005, Refrégier et al 2008), speciation (Devier et al 2010, Gladieux et al 2011), and phylogeny and systematics (Lutz et al 2005, 2008, Denchev et al 2009, Piątek et al 2012, Kemler et al 2013). Ustilago violacea), has been usually assigned to morphologically similar specimens
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