Biology subjects

Joisten-Rosenthal, V.

Publications and source records attributed to Joisten-Rosenthal, V..

4 recordsLinked to original sources

bioRxiv2026

Decoupled evolution of antimicrobial repertoires in lichen-forming fungi

Lichens are stable multipartite symbioses in which a fungal mycobiont associates with one or more photosynthetic partners while hosting complex microbiomes. Secreted antimicrobial proteins (AMPs) have recently emerged as important mediators of fungal interactions with surrounding microbial communities, yet their evolutionary distribution and diversity in lichen-forming fungi remain largely unexplored. Here, we predicted AMP repertoires across 80 phylogenetically diverse lichen-forming fungi representing three photobiont association types. Contrary to our expectation, average repertoire size did not differ between chlorolichens, cyanolichens and tripartite lichens (363 AMPs per species overall), even though repertoire size varied almost five-fold among species and 23 AMP families showed photobiont-associated enrichment or depletion. This quantitative conservation masks extensive compositional turnover, with families occurring in at least 90% of species coexisting alongside numerous lineage-specific groups. Pooled population sequencing of 11 Umbilicaria phaea populations along two elevational gradients further revealed recurrent AMP presence-absence variation within a single species. In contrast to AMPs, biosynthetic gene clusters (BGCs) and carbohydrate-active enzymes (CAZymes), which include known antimicrobials, were markedly reduced in cyanolichens relative to chlorolichens. Lichen-forming fungi thus combine a conserved baseline antimicrobial protein capacity, whose composition nonetheless turns over between lineages and populations, with chemical and enzymatic systems that differentiate along photobiont association and may support ecological and lifestyle-associated adaptation.

microbiology↗

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

DNA-intercalating antiphage molecules trigger abortive infection through mutual destruction and synergize with bacterial immunity

Bacteria deploy diverse antiphage defense systems, including small bioactive molecules providing protection at the multicellular level. DNA-intercalating anthracyclines, such as daunorubicin, exhibit broad antiphage activity, but the underlying mechanism has remained elusive. Here, we systematically screened the Escherichia coli BASEL phage collection to elucidate the mode of action of DNA-intercalating antiphage molecules. We identified taxonomically distinct clusters of susceptible viral groups and show that, in T5-like phages (Markadamsvirinae), daunorubicin blocks infection after first-step transfer (FST). In the presence of daunorubicin, continued expression of pre-early genes leads to abortive infection via mutual destruction, where both phage and host succumb. Analogous abortive-infection phenotypes occur across taxonomically diverse phages exposed to chemically distinct DNA-intercalating molecules. Notably, we show that daunorubicin synergizes with downstream nucleic acid-targeting defenses underscoring context-dependent outcomes. Together, these findings reveal how chemical defense contributes to the multilayered antiviral immunity and highlight the intricate interplay between mechanistic inhibition and infection outcome.

microbiology↗

bioRxiv2025

A fungal root endophyte functionally complements host immunity and mitigates natural immune variation in Arabidopsis

Beneficial root-associated microbes can enhance plant resilience by complementing aspects of host immunity. The fungal root endophyte Serendipita indica (Si) is known to promote plant growth and confer broad stress tolerance. To assess how natural host genetic variation influences Si-mediated protection, we screened 47 Arabidopsis thaliana accessions for susceptibility to the fungal pathogen Bipolaris sorokiniana (Bs) with and without Si colonization. All accessions benefited from Si, indicating that endophyte-mediated disease mitigation occurs broadly across diverse host genotypes. A focused comparison of two genetically and geographically proximate Swedish accessions, T510 and T530, which displayed the most divergent protection scores, revealed substantial differences in Bs susceptibility. Transcriptome profiling under bi- and tripartite colonization showed conserved defense responses in both accessions. Bs infection downregulated growth- and development-related genes, consistent with a growth-immunity trade-off, with T530 exhibiting higher Bs colonization and a stronger transcriptional response than T510. Co-colonization with Si effectively suppressed pathogen growth and disease symptoms in both accessions. Comparative genomic and transcriptomic analyses identified four immune receptor genes, including the TIR-NLR ISI, present in T510 but absent in T530. An isi T-DNA insertion mutant phenocopied the heightened Bs susceptibility of T530, confirming that ISI contributes to root immunity, while Si-mediated protection remained intact despite increased pathogen susceptibility. Together, these findings demonstrate that fungal endophytes can mitigate the functional consequences of natural immune variation and enhance the resilience of genetically diverse plant populations. HighlightsO_LIS. indica confers broad protection against B. sorokiniana largely independent of host genotype or pathogen susceptibility. C_LIO_LIThe TIR-NLR immune receptor ISI contributes to root immunity but is not essential for S. indica-mediated protection. C_LIO_LIBeneficial endophytes can mitigate natural immune variation effects and support overall plant health. C_LI

ecology↗