Biology subjects

Werth, S.

Publications and source records attributed to Werth, S..

5 recordsLinked to original sources

bioRxiv2026

Towards an understanding of the taxonomy of the Eurasian montane riparian genus Myricaria (Tamaricaceae) through Angiosperms353 herbariomics

Myricaria Desv. (Tamaricaceae) is a genus of shrubs that play a keystone role in montane riparian ecosystems across Eurasia, shaping riverine habitats and supporting ecological function. The genus has a centre of origin in the Qinghai-Tibetan Plateau and exhibits a broad distribution, but many species boundaries are unresolved. Here, we present the first phylogenomic analysis of Myricaria using the Angiosperms353 target enrichment bait set, with sampling across its full geographic range. Off-target plastid loci were extracted from next-generation sequencing data using the CAPTUS bioinformatics pipeline. We infer species relationships using ASTRAL-IV and network analysis with SplitsTree, in conjunction with morphology. We also provide a taxonomic treatment of the genus, integrating our morphological observations and phylogenomic analyses for species delimitations. Based on our analyses, recognise two infrageneric sections: sect. Parallelantherae (containing only M. elegans) and sect. Myricaria (the remainder of the genus, with type species M. germanica). We also propose synonymising M. davurica, M. bracteata and M. squamosa with M. germanica. Although species boundaries in the Asian highlands remain unresolved, we conclude that the species M. elegans, M. germanica, M. laxiflora, M. longifolia, M. platyphylla, and M. pulcherrima are well-supported both phylogenomically and morphologically.

plant biology↗

bioRxiv2026

A chromosome-scale super-pangenome of the lichen genus Peltigera reveals genome architecture and expanded interaction repertoires shared across pathogenic and mutualistic fungi

Fungi engage in associations with other organisms across a continuum from pathogenic to mutualistic lifestyles. Hence, they require a compendium of molecular capacities, including partner recognition, extracellular signaling, nutrient exchange, immune modulation, and control of microbial competitors. In filamentous pathogens such traits are frequently associated with compartmentalized genomes, including rapidly evolving secreted proteins known as effectors and expanded receptor families, but it remains unclear whether similar genomic principles shape mutualistic fungal symbioses. Here, we generated a chromosome-scale super-pangenome for the lichen-forming genus Peltigera, comprising 41 mycobiont assemblies representing eleven species, together with genomes of associated Nostoc and, in tripartite species, Coccomyxa photobionts. The mycobiont genomes revealed extensive variation in genome size, transposable element content, biosynthetic gene clusters, and lineage-specific gene content, with pronounced expansions in tripartite species. Across Peltigera, secreted protein encoding genes were preferentially located in TE-rich regions. We further identified Starship-like transposon elements, expanded antimicrobial protein repertoires, and a large, previously underestimated repertoire of fungal GPCRs dominated by Pth11-like receptors. Layer-specific transcriptomics of a P. rufescens thallus showed differential expression of several interaction-associated gene families, e.g. lectins, antimicrobial proteins and Pth11-like GPCRs. These data indicate that pathogenic and mutualistic fungi might exhibit shared genomic principles, including genome compartmentalization, mobile-element-associated diversification, and the expansion of molecular repertoires involved in recognition, extracellular control and signaling.

genomics↗

bioRxiv2026

River network connectivity and postglacial history shape pollen- and seed-mediated gene flow across riparian populations of Myricaria germanica.

River network connectivity and postglacial history jointly shape patterns of pollen-and seed-mediated gene flow in riparian plants, yet their relative contributions across spatial and temporal scales remain incompletely understood. Myricaria germanica Desv., a pioneer riparian shrub formerly widespread along European rivers but now restricted to fragmented headwaters, provides an ideal model to investigate how river systems structure genetic connectivity. We analysed genetic diversity, population structure, and migration across 2,212 individuals from 67 populations spanning 12 Central European river catchments using 20 nuclear and six chloroplast microsatellite loci. By integrating biparentally inherited nuclear markers with maternally inherited chloroplast markers, we disentangled pollen- and seed-mediated gene flow across historical and contemporary timescales. Both marker systems revealed low genetic diversity, high inbreeding, and strong population differentiation. Nuclear microsatellites showed significant isolation by distance and extensive historical connectivity, with coalescent analyses indicating high pollen-mediated gene flow among catchments and identifying the Rhine and Danube as major long-term sources of migrants. In contrast, chloroplast microsatellites exhibited stronger spatial structure, limited admixture, and highly directional historical seed dispersal, consistent with constrained hydrochorous dispersal routes. Contemporary migration analyses further showed that present-day seed-mediated gene flow is largely confined within catchments, despite widespread historical pollen connectivity. Together, these results support a two-phase postglacial history in M. germanica, involving rare, directional seed dispersal during recolonization followed by prolonged pollen-mediated gene flow. Our findings highlight catchments as biologically meaningful management units and underscore the importance of conserving river network connectivity to preserve both the evolutionary legacy and long-term adaptive potential of riparian populations.

genetics↗

bioRxiv2022

High diversity of type I polyketide genes in Bacidia rubella as revealed by the comparative analysis of 23 lichen fungal genomes

Fungi involved in lichen symbioses produce a large array of different secondary metabolites. The high diversity of those substances has been known for decades and are often considered characteristic for taxonomical delimitation in lichen-forming fungi. Polyketides, the most common secondary metabolites, are synthesized by the Type I Polyketide synthases (TI-PKS) comprised of different enzymatic domains. We present a phylogenetic overview of Type I PKS genes recovered from the de-novo sequenced genome of Bacidia rubella in the context of additional twenty-one fungal genomes from the largest radiation of lichen-forming Ascomycetes (Lecanoromycetes) as well as the lichen-forming Eurotiomycete, Endocarpon pusillum. Using de-novo gene prediction and functional annotation combined with a phylogenetic analysis, we provide insights into the biosynthetic potential and PKS gene diversity of lichen-forming fungi. We discuss genes predicted in the lichen-forming fungal genomes in relation to previously characterized PKS genes from other fungi and bacteria. Our results reveal a high number of biosynthetic gene clusters and their gene domain composition. PKS gene content outnumbers known secondary substances produced by the lichen-forming fungi. We were able to assign putative functions to several of those PKS genes in silico, based on similarity to already characterized genes. In particular, we identified a putative PKS23 gene of Bacidia rubella, producing the common lichen substance atranorin. However, we also found that several lichen-forming fungi still possess homologs of different biosynthetic genes without producing the corresponding substances in detectable amounts. Although many PKSs remain without functional assignments in our analysis, our findings highlight that genes from lichen-forming fungi represent an untapped source of novel polyketide compounds. However, additional experimental approaches are necessary to link biosynthetic genes and secondary metabolites with confidence.

evolutionary biology↗

bioRxiv2021

Large differences in carbohydrate degradation and transport potential in the genomes of lichen fungal symbionts

Lichen symbioses are generally thought to be stabilized by the transfer of fixed carbon compounds from a photosynthesizing unicellular symbiont to a fungus. In other fungal symbioses, carbohydrate subsidies correlate with genomic reductions in the number of genes for plant cell wall-degrading enzymes (PCWDEs), but whether this is the case with lichen fungal symbionts (LFSs) is unknown. We predicted genes encoding carbohydrate-active enzymes (CAZymes) and sugar transporters in 17 existing and 29 newly sequenced genomes from across the class Lecanoromycetes, the largest extant clade of LFSs. Despite possessing lower mean numbers of PCWDE genes compared to non-symbiont Ascomycota, all LFS genomes possessed a robust suite of predicted PCWDEs. The largest CAZyme gene numbers, on par with model species such as Penicillium, were retained in genomes from the subclass Ostropomycetidae, which are found in crust lichens with highly specific ecologies. The lowest numbers were in the subclass Lecanoromycetidae, which are symbionts of many generalist macrolichens. Our results suggest that association with phototroph symbionts does not in itself result in functional loss of PCWDEs and that PCWDE losses may have been driven by adaptive processes within the evolution of specific LFS lineages. The inferred capability of some LFSs to access a wide range of carbohydrates suggests that some lichen symbioses may augment fixed CO2 with carbon from external sources. SignificanceLichen symbioses are considered self-contained autotrophic systems in which the total carbon economy is the sum of phototroph-fixed CO2, supplied to a fungus as sugars. In other fungal-plant symbioses, such as mycorrhizae, plant-derived sugar subsidies are associated with loss of plant cell wall-degrading enzymes (PCWDEs). We compared PCWDE inventories in 46 genomes from the largest group of lichen fungal symbionts (LFSs) with non-symbionts from across Ascomycota. We found that despite lower overall gene numbers, all LFSs retain PCWDEs, and some possess gene numbers and functional diversity on par with non-symbionts. Our results suggest that association with a phototroph does not necessarily result in PCWDE loss, and some lichens may obtain carbon from sources other than CO2 fixation.

genomics↗