Markus Scholler

Taxonomy, phylogeny, and distribution of Puccinia graminis, the black stem rust: new insights based on rDNA sequence data

Puccinia graminis (Uredinales) is an economically important and common host-alternating rust species on Berberidaceae/Poaceae (subfamilies Pooideae and Panicoideae) that has been spread globally by human activities from an unknown center of origin. To evaluate the taxonomic implications, phylogenetic relationships, and distribution/spread of this complex species, we sequenced and cladistically analyzed the ITS1, 5.8S, and ITS2 regions from herbarium specimens on various host plants from Iran (17), Europe (1), and North America (4). The ITS region plus the 5.8S gene ranged from 686 to 701 bp, including the flanking partial sequences of the 18S and 28S rDNA. Our phylogenetic analysis included 54 bp of the 18S sequence, the entire ITS1 + 5.8S + ITS2, and 58 bp of the 28S sequence. A second analysis used only the last 42 bp of ITS1, and all the 5.8S and ITS2, to incorporate data from additional sequences downloaded from GenBank. In addition to variation in sequence length, there was variation in sequence content. The analysis does not support classical morphology-based taxonomic concepts of the P. graminis complex. Also, host range, host taxonomy, and geographic origin provide minor information on taxonomic relationships. Puccinia graminis is most probably monophyletic. Coevolutionary aspects can hardly be discussed because of lack of sequence data from alternate host specimens. The occurrence of unrelated fungal taxa on the same host species suggests that, besides coevolution with the host, host jumps and hybridization may have played an important role in the evolution of P. graminis. From rDNA data we conclude that the pathogen was introduced to North America at least twice independently. For a new taxonomic concept, we think the complex has to be split into at least two species. New morphological features and further features other than sequence data, however, must be checked for taxonomic value first and, if necessary, be considered.

How to tackle the molecular species inventory for an industrialized nation-lessons from the first phase of the German Barcode of Life initiative GBOL (2012-2015).

Biodiversity loss is mainly driven by human activity. While concern grows over the fate of hot spots of biodiversity, contemporary species losses still prevail in industrialized nations. Therefore, strategies were formulated to halt or reverse the loss, driven by evidence for its value for ecosystem services. Maintenance of the latter through conservation depends on correctly identified species. To this aim, the German Federal Ministry of Education and Research is funding the GBOL project, a consortium of natural history collections, botanic gardens, and universities working on a barcode reference database for the countrys fauna and flora. Several noticeable findings could be useful for future campaigns: (i) validating taxon lists to serve as a taxonomic backbone is time-consuming, but without alternative; (ii) offering financial incentives to taxonomic experts, often citizen scientists, is indispensable; (iii) completion of the libraries for widespread species enables analyses of environmental samples, but the process may not hold pace with technological advancements; (iv) discoveries of new species are among the best stories for the media; (v) a commitment to common data standards and repositories is needed, as well as transboundary cooperation between nations; (vi) after validation, all data should be published online via the BOLD to make them searchable for external users and to allow cross-checking with data from other countries.

Taxonomy and phylogeny of Puccinia lagenophorae: a study using rDNA sequence data, morphological and host range features

Puccinia lagenophorae is a rust fungus originating from Australasia which has spread throughout the world. A phylogenetic analysis of taxa related to this species was performed using rDNA (LSU, ITS) sequence data. The analyses revealed a well-supported cluster including all specimens of P. lagenophorae. By evaluating morphological and sequence data, the species is taxonomically re-defined and a list of synonyms is provided. Puccinia distincta on Bellis perennis, a species recently separated from P. lagenophorae, P. saccardoi, a species on the Goodeniaceae, and P. byliana, a species so far only known from South Africa, are reduced to synonymy in P. lagenophorae, as are several other species. Our analysis indicates that P. lagenophorae is likely not derived from the northern hemisphere species P. obscura, but from a species from Australia host-alternating between Asteraceae (aecial host) and Cyperaceae/Juncaceae (telial host). Another related species, P. stylidii (on Stylidium sp., Stylidiaceae) may have been derived from the same parental species as P. lagenophorae. From ontogenetical and morphological studies, the presence of pycnia could not be confirmed in the life cycle of this species, and the width of the pedicel of teliospores at the point of attachment was found to be highly variable and not a taxonomic character. The number of known host species is approximately 150, including 41 new host plants recorded herein.

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

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.

Tranzschelia in the Americas revisited: two new species and notes on the Tranzschelia thalictri complex

Two new species of Tranzschelia (Pucciniales) are described from the Americas. Tranzschelia pseudofusca is a microcyclic species on Anemone spp. (Ranunculaceae) with North American distribution. T. mexicana on Prunus salicifolia (Rosaceae) is found in Colombia, Ecuador and Mexico. It is assumed that T. mexicana is a macrocyclic host-alternating species. T. thalictri, a holarctic microcyclic species, has variable morphology and probably is an aggregate of related species. Specimens are documented with scanning electron microscopy (ESEM) and light microscopy including a simple new technique to illuminate urediniospore germ pores. Results are discussed with respect to similar species, distribution and life-cycle characters. A key for American species on telial hosts is provided.

Competing sexual and asexual generic names in Pucciniomycotina and Ustilaginomycotina (Basidiomycota) and recommendations for use

With the change to one scientific name for pleomorphic fungi, generic names typified by sexual and asexual morphs have been evaluated to recommend which name to use when two names represent the same genus and thus compete for use. In this paper, generic names in Pucciniomycotina and Ustilaginomycotina are evaluated based on their type species to determine which names are synonyms. Twenty-one sets of sexually and asexually typified names in Pucciniomycotina and eight sets in Ustilaginomycotina were determined to be congeneric and compete for use. Recommendations are made as to which generic name to use. In most cases the principle of priority is followed. However, eight generic names in the Pucciniomycotina, and none in Ustilaginomycotina, are recommended for protection: Classicula over Naiadella, Gymnosporangium over Roestelia, Helicobasidium over Thanatophytum and Tuberculina, Melampsorella over Peridermium, Milesina over Milesia, Phragmidium over Aregma, Sporobolomyces over Blastoderma and Rhodomyces, and Uromyces over Uredo. In addition, eight new combinations are made: Blastospora juruensis, B. subneurophyla, Cronartium bethelii, C. kurilense, C. sahoanum, C. yamabense, Milesina polypodii, and Prospodium crusculum combs. nov.

Life cycle and life strategy features of Puccinia glechomatis (Uredinales) favorable for extending the natural range of distribution

The objective of this study was to find features in microcyclic rust fungi (Uredinales) on wild host plants favorable for extension of the natural range of distribution. Puccinia glechomatis, a leptosporic rust fungus and its herbal host Glechoma hederacea (Lamiaceae), both natives to Eurasia and introduced in North America, were used for this study. Although the host has been known from North America since the beginning of the nineteenth century, the rust fungus was first observed there only in recent years. Favorable features were identified by studying the life cycle of the rust, including nuclear conditions and seasonal characteristics as well as its spread in North America. The life cycle was studied macroscopically by inoculation experiments, by various light microscope techniques, and by scanning electron microscopy. The spread of the pathogen and its host were reconstructed by evaluating host plant herbarium specimens and databases, literature, and field study data. The studies on P. glechomatis show that, generally for microcyclic rust fungi, establishment and potential for spread are based on several favorable features of both the host (e.g., synanthropic occurence and dispersal, genetic stability, regeneration of vegetative plant parts) and the rust fungus (asexual reproduction/genetic stability, homothallism, propagation with host plant, formation of both leptospores and thick-walled teliospores).

DNA barcoding and phylogenetic analyses of the genus Coleosporium (Pucciniales) reveal that the North American goldenrod rust C. solidaginis is a neomycete on introduced and native Solidago species in Europe

Recently, an unknown rust fungus of the genus Coleosporium appeared in Germany and Switzerland on giant goldenrod, Solidago gigantea, an invasive neophyte from North America, and on the indigenous European goldenrod, S. virgaurea. For identification, DNA barcodes were assembled in the course of the German Barcode of Life (GBOL) project and the investigation of neomycetes in Switzerland. Phylogenetic analyses were performed using ITS and LSU sequences of Coleosporium species representing various host plants and geographic regions. These analyses resulted in the first molecular evidence of the North American rust Coleosporium solidaginis in Europe. Coleosporium solidaginis is split into two subclades that are closely related to Coleosporium asterum, a species on Aster s.l., which was formerly synonymized with C. solidaginis. The genus is divided into an American and a Eurasian clade. This phylogenetic pattern indicates that the geographic distribution, rather than the relationship with host plants, played a major role in the evolution of Coleosporium species. This finding particularly applies to the European species, which are genetically uniform according to the ITS and LSU sequences. Taxonomical consequences are discussed. Coleosporium solidaginis is fragmentarily distributed in Europe. The place of its introduction and host shift to S. virgaurea remains uncertain. Life cycle and propagation are mainly restricted to asexual urediniospores. Telia were found only once and the aecial stage was not observed at all on pine trees. The ecological impact of this neomycete is still unknown, but C. solidaginis has the potential to harm wild and cultivated goldenrods in Europe.

Revision of some central European species of Inocybe (Fr.: Fr.) Fr. subgenus Inocybe, with the description of five new species

The subgenus Inocybe is widespread in the Holarctic but, due to a superficially similar appearance of the species, much of its diversity has been overlooked. In this study, a revision of some Central European species of the subgenus is carried out. On the basis of detailed morphological and phylogenetic investigation, five new species of Inocybe, subgenus Inocybe are described. Three of these are smooth-spored (I. venustissima, I. curcumina, and I. leochroma), and two are nodulose-spored (I. strickeriana and I. villosa). The new species are compared to the type specimens of I. alluvionis, I. angulatosquamulosa, I. hirtelloides,I. pelargonium, I. salicis, I. splendentoides, I. straminipes, and I. terrifera. Inocybe derbschii is confirmed, and a comprehensive description with photographs is given. The morphological species complex consisting of I. furfurea, I. rufotacta, and I. sandrae is disentangled and it is shown that the three names are synonyms. Finally, it is shown that I. stenospora does not belong to the subgenus Mallocybe but to the subgenus Inocybe. All new species and most type specimens were included in molecular phylogenetic analyses. The phylogenetic analyses are well in line with the current perception of species boundaries in Inocybe subg. Inocybe.

Repeated formation of correlated species in Tranzschelia (Pucciniales)

Heteroecism, or alternation between two unrelated hosts, is a widespread phenomenon among rust fungi (Pucciniales). In addition to heteroecism, rust fungi have evolved elaborate life cycles ranging from the five spore stages of macrocyclic species with many variations down to microcyclic species that may produce just two of these stages to complete their life cycles on a single host species. Considering the large number of nearly 8000 described rust fungi species and the high proportion that are host-alternating, heteroecism apparently is a successful strategy for these fungi, at least in terms of species diversity. However, the cost of maintaining a heteroecious strategy with respect to spore production and two different host plant species must be high. In Pucciniales, sister-species pairs that include one host-alternating (heteroecious) and one non-host-alternating (autoecious) species that share a common host are called correlated species. In this study, we tested Tranzschelia species for the existence of correlated species using molecular phylogenetic data. We reveal the presence of three pairs of correlated species within this single genus and suggest that this is a repeating process in the evolution of rust fungi. We show that a heteroecious macrocyclic strategy can be the starting point for deriving microcyclic autoecious species. The high cost of host alternation may be compensated by the fact that it is a facultative process in Tranzschelia with numerous strategies for the species to persist in one or the other host or as overwintering spore. Consequently, the advantage of host alternation seems higher than the cost of (facultative) heteroecism.