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1. Plant species persistence in natural communities requires coping with biotic and abiotic challenges. These challenges also depend on plant community composition and diversity. Over time, biodiversity effects have been shown to be strengthened via increasing species complementarity in mixtures. Little is known, however, whether differences in community diversity and composition induce rapid transgenerational phenotypic adaptive differentiation during community assembly. We expect altered plant–plant and other biotic interactions (mutualists or antagonists) in high vs. low diverse communities to affect immediate within- and between-species trait differentiations due to competition for light and nutrients. 2. Three years after the initiation of a large-scale, long-term biodiversity experiment in Jena, Germany, we tested for effects of varying experimental plant community diversity (1–60 plant species; one to four plant functional groups) and composition (with or without legumes and/or grasses) on phenotypic differentiation and variation of the tall herb Knautia arvensis. We measured reproduction at different diversity levels in the Jena Experiment (residents hereafter) and, in an additional common garden experiment without competition, recorded subsequent offspring performance (i.e. growth, reproductive success and susceptibility to powdery mildew) to test for differentiation in phenotypic expression and variability. 3. We observed phenotypic differences among diversity levels with reduced fecundity of K. arvensis residents in more diverse communities. In the next generation grown under common garden conditions, offspring from high-diversity plots showed reduced growth (i.e. height) and lower reproduction (i.e. fewer infructescences), but increased phenotypic trait variability (e.g. in leaf width and powdery mildew presence) and also tended to be less susceptible to powdery mildew infection. 4. Community composition also affected Knautia parents and offspring. In the presence of legumes, resident plants produced more seeds (increased fecundity); however, germination rate of those seeds was reduced at an early seedling stage (reduced fertility). 5. Synthesis. We conclude that rapid transgenerational effects of community diversity and composition on both mean and variation of phenotypic traits among offspring exist. In addition to heritable variation, environmentally induced epigenetic and/or maternal processes matter for early plant community assembly and may also determine future species coexistence and community stability.

Species of rust fungi of the genus Milesina (Pucciniastraceae, Pucciniales) are distributed mainly in northern temperate regions. They host-alternate between needles of fir ( Abies spp.) and fronds of ferns (species of Polypodiales). Milesina species are distinguished based on host taxonomy and urediniospore morphology. In this study, 12 species of Milesina from Europe were revised. Specimens were examined by light and scanning electron microscopy for urediniospore morphology with a focus on visualising germ pores (number, size and position) and echinulation. In addition, barcode loci (ITS, nad6, 28S) were used for species delimitation and for molecular phylogenetic analyses. Barcodes of 72 Milesina specimens were provided, including 11 of the 12 species. Whereas urediniospore morphology features were sufficient to distinguish all 12 Milesina species except for 2 ( M.blechni and M.kriegeriana ), ITS sequences separated only 4 of 11 species. Sequencing with 28S and nad6 did not improve species resolution. Phylogenetic analysis, however, revealed four phylogenetic groups within Milesina that also correlate with specific urediniospore characters (germ pore number and position and echinulation). These groups are proposed as new sections within Milesina (sections Milesina , Vogesiacae M. Scholler & Bubner, sect. nov. , Scolopendriorum M. Scholler & Bubner, sect. nov. and Carpaticae M. Scholler & Bubner, sect. nov. ). In addition, Milesinawoodwardiana Buchheit & M. Scholler, sp. nov. on Woodwardiaradicans , a member of the type section Milesina, is newly described. An identification key for European Milesina species, based on urediniospore features, is provided.

Fungal plant pathogens are common in natural communities where they affect plant physiology, plant survival, and biomass production. Conversely, pathogen transmission and infection may be regulated by plant community characteristics such as plant species diversity and functional composition that favor pathogen diversity through increases in host diversity while simultaneously reducing pathogen infection via increased variability in host density and spatial heterogeneity. Therefore, a comprehensive understanding of multi‐host–multi‐pathogen interactions is of high significance in the context of biodiversity–ecosystem functioning. We investigated the relationship between plant diversity and aboveground obligate parasitic fungal pathogen (“pathogens” hereafter) diversity and infection in grasslands of a long‐term, large‐scale, biodiversity experiment with varying plant species (1–60 species) and plant functional group diversity (1–4 groups). To estimate pathogen infection of the plant communities, we visually assessed pathogen‐group presence (i.e., rusts, powdery mildews, downy mildews, smuts, and leaf‐spot diseases) and overall infection levels (combining incidence and severity of each pathogen group) in 82 experimental plots on all aboveground organs of all plant species per plot during four surveys in 2006. Pathogen diversity, assessed as the cumulative number of pathogen groups on all plant species per plot, increased log‐linearly with plant species diversity. However, pathogen incidence and severity, and hence overall infection, decreased with increasing plant species diversity. In addition, co‐infection of plant individuals by two or more pathogen groups was less likely with increasing plant community diversity. We conclude that plant community diversity promotes pathogen‐community diversity while at the same time reducing pathogen infection levels of plant individuals.

There are 63 known species of Thecaphora (Glomosporiaceae, Ustilaginomycotina), a third of which occur on Asteraceae. These smut fungi produce yellowish-brown to reddish-brown masses of spore balls in specific, mostly regenerative, plant organs. A species of Thecaphora was collected in the flower heads of Anthemischia (Anthemideae, Asteraceae) on Rhodes Island, Greece, in 2015 and 2017, which represents the first smut record of a smut fungus on a host plant species in this tribe. Based on its distinctive morphology, host species and genetic divergence, this species is described as Thecaphoraanthemidis sp. nov. Molecular barcodes of the ITS region are provided for this and several other species of Thecaphora . A phylogenetic and morphological comparison to closely related species showed that Th.anthemidis differed from other species of Thecaphora . Thecaphoraanthemidis produced loose spore balls in the flower heads and peduncles of Anthemischia unlike other flower-infecting species.

Plant diversity and ecosystem function An eight-year study of the effects of biodiversity on ecosystem functioning across the food web suggests that plant diversity has strong bottom-up effects on biotic interactions. The experiment by Scherber et al . manipulated plant species in specially seeded grassland plots and monitored species richness of herbivores, carnivores and all other relevant groups, and their interactions. The effects are consistent across groups, but are stronger at adjacent trophic levels and in above-ground groups rather than below-ground groups. Responses to increasing plant diversity were generally positive, but were negative for biological invasion, pathogen infestation and hyperparasitism. The effects of biodiversity on ecosystem function are usually studied within trophic levels. These authors conduct a large experiment across trophic levels to show how manipulations of plant diversity affect function in different groups. The effects are consistent across groups, but are stronger at adjacent trophic levels and in above-ground rather than below-ground groups. Biodiversity is rapidly declining 1 , and this may negatively affect ecosystem processes 2 , including economically important ecosystem services 3 . Previous studies have shown that biodiversity has positive effects on organisms and processes 4 across trophic levels 5 . However, only a few studies have so far incorporated an explicit food-web perspective 6 . In an eight-year biodiversity experiment, we studied an unprecedented range of above- and below-ground organisms and multitrophic interactions. A multitrophic data set originating from a single long-term experiment allows mechanistic insights that would not be gained from meta-analysis of different experiments. Here we show that plant diversity effects dampen with increasing trophic level and degree of omnivory. This was true both for abundance and species richness of organisms. Furthermore, we present comprehensive above-ground/below-ground biodiversity food webs. Both above ground and below ground, herbivores responded more strongly to changes in plant diversity than did carnivores or omnivores. Density and richness of carnivorous taxa was independent of vegetation structure. Below-ground responses to plant diversity were consistently weaker than above-ground responses. Responses to increasing plant diversity were generally positive, but were negative for biological invasion, pathogen infestation and hyperparasitism. Our results suggest that plant diversity has strong bottom-up effects on multitrophic interaction networks, with particularly strong effects on lower trophic levels. Effects on higher trophic levels are indirectly mediated through bottom-up trophic cascades.

Floricolous downy mildews are a monophyletic group of members of the genus Peronospora (Oomycota, Peronosporales). These downy mildews can be found on a variety of families of the Asteridae, including Asteraceae, Campanulaceae, Dipsacaceae, Lamiaceae, and Orobanchaceae. With the exception of Peronospora radii, which can also cause economically relevant losses, sporulation usually takes place only on floral parts of their hosts. However, only very few specimens of these mostly inconspicuous downy mildews have so far been included in molecular phylogenies. Focusing on Lamiaceae, we have investigated multiple specimens of floricolous downy mildews for elucidating species boundaries and host specificity in this group. Based on both mitochondrial and nuclear loci, it became apparent that phylogenetic lineages in the Lamiaceae seem to be host genus specific and significant sequence diversity could be found between lineages. Based on distinctiveness in both phylogenetic reconstructions and morphology, the downy mildew on flowers of Stachys palustris is introduced as a new species, Peronospora jagei sp. nov., which can be morphologically distinguished from Peronospora stigmaticola by broader and shorter conidiospores. The diversity of the floricolous down mildews might be higher than previously assumed, although specimens from a much broader set of samples will be needed to confirm this view. © 2012 German Mycological Society and Springer.

The oomycete Plasmopara obducens was first described on wild Impatiens noli-tangere in Germany in 1877. About 125 years later the first occurrence of P. obducens on cultivated I. walleriana in the United Kingdom was reported, and a worldwide epidemic followed. Although this pathogen is a major threat for ornamental busy lizzy, the identity of the pathogen remained unconfirmed and the high host specificity observed for the genus Plasmopara cast doubts regarding its determination as P. obducens . In this study, using multigene phylogenies and morphological investigation, it is revealed that P. obducens on I. noli-tangere is not the conspecific with the pathogen affecting I. walleriana and another ornamental balsam, I. balsamina . As a consequence, the new names P. destructor and P. velutina are introduced for the pathogens of I. walleriana and I. balsamina , respectively.

Species of rust fungi of the genus (Pucciniastraceae, Pucciniales) are distributed mainly in northern temperate regions. They host-alternate between needles of fir ( spp.) and fronds of ferns (species of Polypodiales). species are distinguished based on host taxonomy and urediniospore morphology. In this study, 12 species of from Europe were revised. Specimens were examined by light and scanning electron microscopy for urediniospore morphology with a focus on visualising germ pores (number, size and position) and echinulation. In addition, barcode loci (ITS, nad6, 28S) were used for species delimitation and for molecular phylogenetic analyses. Barcodes of 72 specimens were provided, including 11 of the 12 species. Whereas urediniospore morphology features were sufficient to distinguish all 12 species except for 2 ( and ), ITS sequences separated only 4 of 11 species. Sequencing with 28S and nad6 did not improve species resolution. Phylogenetic analysis, however, revealed four phylogenetic groups within that also correlate with specific urediniospore characters (germ pore number and position and echinulation). These groups are proposed as new sections within (sections , M. Scholler & Bubner, , M. Scholler & Bubner, and M. Scholler & Bubner, ). In addition, Buchheit & M. Scholler, on , a member of the type section Milesina, is newly described. An identification key for European species, based on urediniospore features, is provided.

There are 63 known species of Thecaphora (Glomosporiaceae, Ustilaginomycotina), a third of which occur on Asteraceae. These smut fungi produce yellowish-brown to reddish-brown masses of spore balls in specific, mostly regenerative, plant organs. A species of Thecaphora was collected in the flower heads of Anthemischia (Anthemideae, Asteraceae) on Rhodes Island, Greece, in 2015 and 2017, which represents the first smut record of a smut fungus on a host plant species in this tribe. Based on its distinctive morphology, host species and genetic divergence, this species is described as Thecaphoraanthemidissp. nov. Molecular barcodes of the ITS region are provided for this and several other species of Thecaphora. A phylogenetic and morphological comparison to closely related species showed that Th.anthemidis differed from other species of Thecaphora. Thecaphoraanthemidis produced loose spore balls in the flower heads and peduncles of Anthemischia unlike other flower-infecting species.

The genus Thlaspi has been variously subdivided since its description by Linnaeus in 1753, but due to similarities in fruit shape several segregates have still not gained broad recognition, despite the fact that they are not directly related to Thlaspi. This applies especially to segregates now considered to belong to the tribe Coluteocarpeae, which includes several well-studied taxa, e.g., Noccaea caerulescens (syn. Thlaspi caerulescens), and the widespread Microthlaspi perfoliatum (syn. Thlaspi perfoliatum). The taxonomy of this tribe is still debated, as a series of detailed monographs on Coluteocarpeae was not published in English and a lack of phylogenetic resolution within this tribe was found in previous studies. The current study presents detailed phylogenetic investigations and a critical review of morphological features, with focus on taxa previously placed in Microthlaspi. Based on one nuclear (ITS) and two chloroplast (matK, trnL-F) loci, four strongly supported major groups were recovered among the Coluteocarpeae genera included, corresponding to Ihsanalshehbazia gen. nov., Friedrich-karlmeyeria gen. nov., Microthlaspi s.str., and Noccaea s.l. In addition, two new species of Microthlaspi, M. sylvarum-cedri sp. nov. and M. mediterraneo-orientale sp. nov., were discovered, which are well supported by both morphological and molecular data. Furthermore, M. erraticum comb. nov. (diploid) and M. perfoliatum s.str. (polyploid) were shown to be distinct species, phylogenetically widely separate, but with some overlap in several morphological characters. Detailed descriptions, notes on taxonomy, geographical distribution, and line drawings for the new species and each species previously included in Microthlaspi are provided. In addition, the current taxonomic state of the tribe Coluteocarpeae is briefly discussed and it is concluded that while several annual taxa are clearly distinct from Noccaea, many perennial taxa, after thorough phylogenetic and morphological investigations, may have to be merged with this genus.