A taxonomic and phylogenetic study of the Golovinomyces biocellatus complex (Erysiphales, Ascomycota) using asexual state morphology and rDNA sequence data

Abstract

The Golovinomyces biocellatus complex consists of powdery mildew (Erysiphales) species restricted to hosts of the family Lamiaceae. Previous authors used minor morphological features of the sexual state and host range data to split the complex. The data, however, were not sufficient to define a convincing species concept. Our taxonomic study is based on molecular phylogenetic and asexual state morphology data. For morphological studies, mainly features of the asexual morph (conidiophores, conidia, germination patterns) were studied using light and scanning electron microscopy. Detailed line drawings of asexual state features are provided. For phylogenetic analyses, two markers (rDNA: ITS, LSU) of 64 specimens were applied. The phylogeny resulted in two major clades. Clade I consists of specimens with Lamiaceae hosts and three specimens of Verbena. Clade II consists of two sister groups, the first (IIa) with Salvia spp. and the second (IIb) with Lycopus europaeus (the type host G. biocellatus) and Glechoma. Clades I and IIb and two subclades of IIa with Salvia hosts are characterized by specific morphological traits (differences in conidiophore length, conidial shape, width, and germination patterns). Based on these data, we suggest to consider specimens of clades I (including specimens on Verbena) and IIb and the two subclades of IIa as distinct species, namely G. monardae, G. biocellatus, G. salviae, and G. neosalviae sp. nov. A key for the identification of species based on asexual state features is provided. The results are discussed with respect to host range, jumps, co-evolutionary aspects, and distribution patterns.

Multi-locus phylogeny and taxonomy of an unresolved, heterogeneous species complex within the genus Golovinomyces (Ascomycota, Erysiphales), including G. ambrosiae, G. circumfusus and G. spadiceus

“…Golovinomyces is characterized by having chasmothecia with mycelioid appendages, several, mostly 2spored asci, an asexual morph with catenescent conidia that lack fibrosin bodies, and mostly nipple-shaped appressoria. Golovinomyces currently encompasses 57 species and 5 varieties [1,[8][9][10][11][12][13]. Erysiphe cichoracearum [14] included nearly all of the species that are now assigned to Golovinomyces.…”

First report of powdery mildew caused by Golovinomyces monardae on peppermint in Italy

“…To our knowledge, this is the first report of powdery mildew caused by Golovinomyces monardae on peppermint in Italy. According to taxonomic and phylogenetic studies of the Golovinomyces biocellatus complex (Scholler et al 2016) the same pathogen has been reported on peppermint in Germany, on Mentha spicata in Italy and on other hosts belonging to Lamiaceae and Verbenaceae (Garibaldi et al 2010;Scholler et al 2016 …”

“…Based on morphology, the causal agent was determined as Golovonomyces spp. (Scholler et al 2016). The internal transcribed spacer region of rDNA of the pathogen was amplified using the primers ITS1/ITS4 and sequenced (GenBank Accession MG205583).…”

Taxonomy of the Golovinomyces cynoglossi Complex (Erysiphales, Ascomycota) Disentangled by Phylogenetic Analyses and Reassessments of Morphological Traits

“…Although ITS sequences are commonly and widely used for powdery mildews, they are often not sufficiently reliable for final taxonomic conclusions on the species level [23,24]. However, in this scenario, sequence data are indispensable for the clarification of the G. cynoglossi complex.…”