Biology subjects

Roth, O.

Publications and source records attributed to Roth, O..

At least 19 recordsLinked to original sources

bioRxiv2026

Spatially-restricted metabolic delivery of auxin for selective adventitious root induction

Auxin impacts on nearly every aspect of plant growth and development. Its exogenous application therefore results in pleiotropic growth responses. Exploiting this activity for plant propagation requires avoiding or minimizing such off-target effects and is generally achieved as a trade-off between toxicity and organogenetic efficacity. We recently identified the compound HYSPARIN (HYS) with potent, and uniquely selective adventitious root inductive activity. Unlike other root-inducing compounds, HYS preferentially activates auxin responses in the shoot via an unknown mechanism. Here, we show that HYS acts as a shoot-specific proauxin. Rather than acting through auxin homeostasis, we found that HYS is hydrolysed in planta independently of ILR1/ILL amidohydrolases to release the synthetic auxin MCPA. Structure-activity relationship analysis confirmed a strong dependence on its MCPA moiety for activating auxin responses, and identified its promoiety as a determinant of shoot-specificity and activity. Selective application of MCPA also potently induces AR is consistent with a model in which HYS metabolism produces a spatially restricted, AR inductive auxin signal. The activation mechanism of HYS thus provides a conceptual framework for tissue-specific metabolic delivery of auxin and may enable the programmable delivery of other xenobiotics in plants.

plant biology↗

bioRxiv2026

Plant pathogens cleave 2′cADPR to suppress TIR immune signaling

Small molecules produced by TIR (Toll-interleukin-1 receptor) domains are essential for plant immune signaling. A central TIR-derived signal is 2'cADPR, a cyclic ADP-ribose (ADPR) molecule that is generated by plant TIR-domain proteins upon sensing pathogen infection. Here we show that XopQ, a virulence protein widespread in plant pathogenic bacteria, cleaves 2'cADPR and converts it into an inactive, linear ADPR molecule. Steady-state kinetic analyses revealed that XopQ is a highly efficient enzyme that hydrolyzes 2'cADPR with near diffusion-limited catalytic efficiency, while displaying high specificity and no detectable activity toward closely related molecules such as 3'cADPR. We show that XopQ eliminates 2'cADPR in planta and prevents accumulation of pRib-AMP, a derivative of 2'cADPR that activates the downstream immune complex EDS1-PAD4. Our data demonstrate that XopQ inhibits PAD4-dependent plant immunity and can promote pathogen virulence even when the pathogen carries an avirulence effector that triggers TIR-mediated immune signaling. Finally, we show that XopQ can also inhibit type VI Thoeris, a bacterial anti-phage defense system that relies on 2'cADPR signaling, possibly explaining why XopQ and type VI Thoeris are not observed co-occurring in bacterial genomes. Our findings uncover a widespread and conserved strategy used by plant pathogens to directly target host TIR signaling.

Plant Biology↗

bioRxiv2026

Conserved catalytic activity of immune TIR domains in animals

The Toll/interleukin-1 receptor (TIR) domain is important for immune signaling across bacteria, plants, and animals. In human innate immunity, TIR domains are known to function as adaptors mediating protein-protein interactions, yet studies in bacteria and plants revealed that TIR domains often act as enzymes that produce immune signaling molecules. Here, we show that TIR domains from evolutionarily diverse animals have conserved active sites, implying that they can function as enzymes. In vitro experiments with animal TIRs show that the TIR domain of several Toll-like receptors (TLRs), including that of human TLR4, can produce cyclic ADP-ribose (cADPR), revealing an enzymatic activity previously unknown for TLR TIRs. We show that production of cADPR is a conserved feature of TIR domains across the animal tree of life, implying a role for this molecule in animal TIR signaling. Finally, we report a TIR domain from green algae that synthesizes 3'cADPR, suggesting conservation of 3'cADPR signaling between bacteria and eukaryotes. Our results reveal that the catalytic activity of TIR domains is widespread in animals and conserved across the tree of life.

immunology↗

bioRxiv2025

Parental fasting effects on offspring immune gene expression and gut microbiota in a species with male pregnancy (Syngnathus typhle).

Intermittent fasting is widely promoted for its potential to improve health and extend lifespan, yet these benefits may come at a reproductive cost, potentially reducing parental fitness and offspring quality. While the inter- and transgenerational effects of fasting are increasingly studied, they remain poorly understood in species with unconventional reproductive roles. Investigating such effects in these systems is crucial, as the evolutionary trade-offs between somatic maintenance and reproductive investment may differ from those in species with conventional reproductive roles. In this study, we investigated the effects of intermittent fasting (IF) in a species with male pregnancy, Syngnathus typhle, by exposing mothers and fathers to either IF or ad libitum (AL) feeding before mating. Upon transfer of maternal eggs to paternal brood pouches, males remained on their assigned diets throughout pregnancy. Offspring from all parental diet combinations AL(p)xAL(m), IF(p)xIF(m), AL(p)xIF(m), IF(p)xAL(m) were analyzed at birth before first feeding alongside parents for morphology, immune and epigenetic candidate gene expression, and gut microbiota composition. Mothers under IF showed greater condition loss, leading to reduced offspring condition regardless of paternal diet, highlighting the importance of maternal provisioning through eggs. However, IF fathers exhibited increased immune activation and microbiome shifts that were mirrored in offspring, suggesting paternal priming via epigenetic and microbial inheritance. Offspring from mismatched parental diets showed disrupted immune-microbiome correlations, indicating that aligned parental cues support more stable offspring development. These findings highlight how parental nutritional history shapes offspring resilience and emphasize the value of studying species with diverse reproductive strategies and life histories to understand the full spectrum of trans-generational plasticity in nature.

evolutionary biology↗

bioRxiv2024

Evaluating bacteriophage impact on gut microbiome composition in broad-nosed pipefish (Syngnathus typhle)

Bacteriophages play a crucial role in shaping microbial community dynamics in marine systems and have the potential to stimulate surges in pathogenic bacteria facilitating disease outbreaks. Notwithstanding, bacteriophages also serve as valuable biocontrol agents, underscoring their huge potential for aquaculture therapy treatments. Insights into the intricate tripartite interplay upon an infection with a virulent bacterium, its specific phages and the eukaryotic microbiome could improve our understanding of how bacteria-phage interactions behave in a natural microbial system. This investigation assessed the influence of a virulent Vibrio alginolyticus (K01M1) infection, in tandem with lytic ([fe]St2) and filamentous ([fe]K04M1) Vibrio-specific phages, on the broad-nosed pipefish (Syngnathus typhle) gut microbiome using 16S rRNA amplicon sequencing and non-intrusive gastric swabbing. Microbial communities and diversity metrics were not permanently impacted by Vibrio and phage introductions, while the different infection regimes shaped Vibrio-specific dynamics. In the filamentous phage and Vibrio-only treatments, V. alginolyticus abundances spiked 12 hours post-ingestion. In contrast, V. alginolyticus numbers in the lytic phage and control treatment were significantly reduced, suggesting phage activity and specific elimination of the introduced bacteria. Assisted by relative true-gut tissue samples, a newly implemented non-intrusive swabbing method was successful at discerning the activity of two contrasting phages and supports previous work that encourages the use of [fe]St2 in bacteriophage treatments. Identifying Vibrio-specific phages with similar positive characteristics could be beneficial for the aquaculture trade, which is currently heavily impacted by the antibiotic crisis.

microbiology↗

bioRxiv2024

Shaping tiny worlds: Paternal microbiota manipulation influences offspring microbial colonization and development in a sex role-reversed pipefish

Microbes are acquired through vertical and environmental horizontal transmission. Vertical transmission is directly linked to reproductive success and entails early transmission, facilitating coexistence of host and microbes over generations. The multiple potentially interacting routes of vertical transmission are challenging to be disentangled in conventional sex-role species, as they are mostly intermingled on the maternal side, i.e., through egg production, pregnancy, birth and postnatal care. The evolution of male pregnancy in syngnathids (pipefishes and seahorses) offers an opportunity to separate vertical microbial provisioning through the egg (maternal) from provisioning through pregnancy (paternal). We experimentally evaluated the existence and role of paternal microbiota provisioning through male pregnancy on offspring development and microbial colonization. Male pipefish were exposed to antibiotics, and subsequently recolonized with bacteria of paternal, maternal, and environmental origin (spike treatment). After pregnancy, the microbiome (16s rRNA) of developing offspring was repeatedly ribotyped. Paternal antibiotic and spike treatments influenced the microbial composition of the brood pouch and offspring microbiome development. Paternal spike treatment gave offspring a kickstart in life by reducing pregnancy duration and inducing offspring survival. Expanding on how distinct vertical microbial transmission routes shape offspring microbiome will foster our understanding of the holobiont function in health and disease.

evolutionary biology↗

bioRxiv2024

Parent-specific transgenerational immune priming enhances offspring defense - unless heat-stress negates it all

Trans-generational immune priming (TGIP) adjusts offspring immune responses based on parental immunological experiences - a form of trans-generational plasticity predicted to be adaptive when parent-offspring environmental conditions match. In contrast, mis-matches between environmental conditions negate those advantages, rendering TGIP costly when mismatched immunological offspring phenotypes are induced. Particularly maternal TGIP was thought to shape offspring immunological preparedness: mothers eggs contain more substance than sperm and, in viviparous species, pregnancy provides additional avenues for immune priming of developing offspring. The syngnathids (pipefishes and seahorses) unique male pregnancy provides an unusual perspective to the ecological relevance of TGIP in a system where egg production and pregnancy occur in different sexes. We simulated parental bacteria exposure in broad nosed pipefish, Syngnathus typhle, through vaccinations with heat-killed Vibrio aestuarianus before mating the fish to each other or control individuals. Resulting offspring were raised, and some exposed to V. aestuarianus, in a control or heat-stress environment, after which transcriptome and microbiome compositions were investigated. Transcriptomic TGIP effects were only observed in Vibrio-exposed offspring at control temperatures, arguing for low costs of TGIP in non-matching environments. Transcriptomic phenotypes elicited by maternal and paternal TGIP had only limited overlap and were not additive. Both transcriptomic responses were significantly associated to immune functions, and specifically the paternal response to the innate immune branch. TGIP of both parents reduced the relative abundance of the experimental Vibrio in exposed offspring, showcasing its ecological effectiveness. Despite its significance in matching biotic environments, no TGIP-associated phenotypes were observed for heat-treated offspring. Heat-spikes caused by climate change thus threaten TGIP benefits, potentially increasing susceptibility to emerging marine diseases. This highlights the urgent need to understand how animals will cope with climate-induced changes in microbial assemblages by illustrating the importance - and limits - of TGIP in mitigating the impacts of environmental stressors on offspring vulnerability.

evolutionary biology↗

bioRxiv2023

Surviving on limited resources: effects of caloric restriction on growth, gene expression and gut microbiota in a species with male pregnancy (Hippocampus erectus).

Caloric restriction (CR) studies have traditionally focused on species with conventional reproductive roles, emphasizing females greater investment in costly gametes and parental care. While the divergent impact of CR on males and females is evident across species, the factors driving this variation, i.e., resource allocation to reproductive elements as part of distinct life history strategies, remain unclear. To address this, we investigated the effects of CR on development, gene expression, and intestinal microbiota in the lined seahorse Hippocampus erectus, a species with male pregnancy, where fathers invest in offspring through gestation. Juvenile seahorses were subjected to ad libitum (AL) or CR feeding for 5 months. CR stunted male growth and brood pouch development, reflecting the energy demands of this crucial parental care trait. However, condition index declined in CR females but not males, while ovarian weight remained unchanged. Transcriptome analysis demonstrated organ- and sex-specific responses to CR with distinct lipid and energy-related pathways activated in male and female livers, indicative of survival enhancement strategies. CR had minimal impact on genes associated with spermatogenesis, but downregulated lipid metabolic and inflammatory genes in ovaries, emphasizing the importance of pre-copulatory resource allocation in female gametes. CR strongly shaped gut microbial composition, creating distinct communities from AL seahorses while also driving sex-specific taxonomic differences. Our research indicates that nutrient limitatio[n]s impact on males and females is influenced by their allocation of resources to reproduction and parental investment. We underscore the significance of studying species with diverse reproductive strategies, sex roles, and life-history strategies.

evolutionary biology↗

bioRxiv2023

Sexual antagonism and sex determination in three syngnathid species alongside male pregnancy gradient and varying sex roles.

The allocation of energy towards gamete production, parental care, mate choice, sex roles, and sexual dimorphism generates divergence in selection pressures between the sexes, leading to opposing fitness strategies and sexual antagonism (SA). Due to the shared genetic makeup, a single genomic locus can contain a gene or allele with differing fitness impacts on each sex. This intralocus sexual conflict can be resolved via intersex bias in gene expression and/or formation of sex-linked genomic regions, that may also regulate sex determination. Sex determination (SD) encompasses environmental SD (ESD), monogenic SD, and polygenic SD. Occasionally, shifts from one SD locus to another can occur. While the precise mechanisms driving these shifts are unknown, SA is believed to be a major contributor. To investigate the link between SA and SD, we selected three syngnathid species along the gradient of male pregnancy that evolved with different sex roles and intensities of sexual dimorphism. By looking at intersex genetic divergence (Fst) and sex-biased expression patterns, we uncovered that sex role and mate competition, rather than male pregnancy, primarily drive SA. Furthermore, we identified processes related to non-coding RNAs and biased allele expression as mediators of SA. Most notably, we discovered intraspecies sex chromosome polymorphism in Hippocampus erectus. Overall, we report important details on the interplay between SA and SD, and suggest that understanding SA and its resolution mechanisms is crucial for unraveling the evolution of SD in diverse species.

evolutionary biology↗

bioRxiv2023

The effect of parental age on the quantity and quality of offspring in Syngnathus typhle, a species with male pregnancy.

Offspring quantity and quality are known to vary according to parental age, with most studies focusing on the mothers age, who produces costly eggs and often carries out pregnancy, hampering to distinction between trans-generational age effects due to egg quality or physiological deterioration. We investigated the ramification of parental age on the offspring in the broad-nosed pipefish Syngnathus typhle, a fish species with male pregnancy, allowing us to separate these two female traits. By mating parents of different sizes we examined the impact of parental age on offspring number, size and gene expression. Our results show that older parents produced more and larger-sized offspring. However, we revealed intriguing insights into the differential gene expression patterns in offspring, strongly influenced by the paternal lineage but minimally affected by maternal age. Offspring from old fathers exhibited notable changes in gene expression profiles, particularly related to cell cycle regulation, metabolism, protein synthesis, stress response, DNA repair and neurogenesis. Our findings provide valuable insights into the role of pregnancy in shaping offspring physiology. Moreover, we recognize the value of assessing a broader range of species that have evolved with sex-specific differences in parental investment vs. gamete provisioning, as the age of either the mother or father may hold greater significance than the other in influencing offspring fitness.

evolutionary biology↗

bioRxiv2023

Sex or sex role - unravelling the evolutionary route of sex-specific senescence

Sexual dimorphism, the divergence in morphological traits between males and females of the same species, is often accompanied by sex-biased gene expression. However, the majority of research has focused on species with conventional sex roles, where females have the highest energy burden with both egg production and parental care, neglecting the diversity of reproductive roles found in nature. We investigated sex-biased gene expression in the broadnosed pipefish (Syngnathus typhle), a sex-role reversed species with male pregnancy, allowing us to separate these two female traits. Employing RNA sequencing, we examined gene expression across organs (brain, head kidney, gonads) at various life stages, encompassing differences in age, sex, and reproductive status. While some gene groups were more strongly associated with sex roles, such as stress resistance and immune defence, others were driven by biological sex, such as energy and lipid storage regulation in an organ- and age-specific manner. By investigating how genes regulate and are regulated by changing reproductive roles and resource allocation in a model system with unconventional life-history strategy, we aim to enhance our understanding of the importance of sex and sex role in regulating gene expression patterns, broadening the scope of this discussion to encompass a wide range of organisms.

evolutionary biology↗

bioRxiv2023

COMPLETE GENOME SEQUENCE OF VIBRIO SYNGNATHI SP. NOV., A FISH PATHOGEN, ISOLATED FROM THE KIEL FJORD

A new Vibrio strain K08M4T was isolated from the broad-nosed pipefish Syngnathus typhle in the Kiel Fjord. Infection experiments revealed that K08M4T is highly virulent for juvenile pipefish. Cells of strain K08M4T are Gram-stain-negative, curved rod-shaped and motile by means of a single polar flagellum. The strain can grow aerobically at 9 to 40{degrees}C, at pH 4 to 10.5 and tolerates up to 12% (w/v) NaCl. The most prevalent (> 10%) cellular fatty acids of K08M4T were C16:1{omega} 7c and C16:0. Whole-genome comparisons revealed that K08M4T represents a separate evolutionary lineage which is distinct from other Vibrio species and falls within the Vibrio Splendidus clade. The genome is 4,886,292 bp in size, consists of two circular chromosomes (3,298,328 bp, 1,587,964 bp), and comprises 4,178 protein-coding genes and 175 RNA genes. In this study, we describe the phenotypic features of the new isolate and present the annotation and analysis of its complete genome sequence. Based on these data, the new isolate represents a new species for which we propose the name Vibrio syngnathi. The type strain is K08M4T (=DSM 109818T). Supplementary materialOne supplementary figure and six supplementary table are available with the online version of the Manuscript.

microbiology↗

bioRxiv2023

Alleviating the barrier of adventitious roots formation in recalcitrant mature tissue by slow release of a synthetic auxin

Clonal propagation of plants by induction of adventitious roots (ARs) from stem cuttings is a requisite step in breeding programs. A major barrier exists for propagating valuable plants that naturally have low capacity to form ARs. Due to the central role of auxin in organogenesis, indole-3-butyric acid (IBA) is often used as part of commercial rooting mixtures, yet many recalcitrant plants do not form ARs in response to this treatment. Here, we describe the synthesis and screening of a focused library of synthetic auxin conjugates in Eucalyptus grandis cuttings and identify 4-chlorophenoxyacetic acid-L-tryptophan-OMe as a competent enhancer of adventitious rooting in a number of recalcitrant woody plants, including apple and argan. Comprehensive metabolic and functional analyses reveal that this activity is engendered by prolonged auxin signaling due to initial fast uptake and slow release and clearance of the free auxin 4-chlorophenoxyacetic acid. This work highlights the utility of a slow-release strategy for bioactive compounds for more effective plant growth regulation.

plant biology↗

bioRxiv2023

The source of microbial transmission influences niche colonization and microbiome development

Early life microbial colonizers shape and support the immature vertebrate immune system. Microbial colonization relies on the vertical route via parental provisioning and the horizontal route via environmental contribution. Vertical transmission is mostly a maternal trait making it hard to determine the source of microbial colonization in order to gain insight in the establishment of the microbial community during crucial development stages. The evolution of unique male pregnancy in pipefishes and seahorses enables the disentanglement of both horizontal and vertical transmission, but also facilitates the differentiation of maternal vs. paternal provisioning ranging from egg development, to male pregnancy and early juvenile development. Using 16s rRNA amplicon sequencing and source-tracker analyses, we revealed how the distinct origins of transmission (maternal, paternal & horizontal) shaped the juvenile internal and external microbiome establishment in the broad-nosed pipefish Syngnathus typhle. Paternal provisioning mainly shaped the juvenile external microbiome, whereas maternal microbes were the main source of the internal juvenile microbiome, later developing into the gut microbiome. This suggests that stability of niche microbiomes may vary depending on the route and time point of colonization, the strength of environmental influences (i.e., horizontal transmission), and potentially the homeostatic function of the niche microbiome.

evolutionary biology↗

bioRxiv2022

SUB-OPTIMAL ENVIRONMENTAL CONDITIONS PROLONG PHAGE EPIDEMICS IN BACTERIAL POPULATIONS

Infections by filamentous phages influence bacterial fitness in various ways. While phage-encoded accessory genes, e.g., virulence genes, can be highly beneficial, the production of viral particles is energetically costly and often reduces bacterial growth. Consequently, if costs outweigh benefits, bacteria evolve resistance which can shorten phage epidemics. Abiotic conditions are known to influence the net-fitness effect for infected bacteria. Their impact on the dynamics and trajectories of host resistance evolution, however, remains yet unknown. To address this, we experimentally evolved the bacterium Vibrio alginolyticus in the presence of a filamentous phage at three different salinity levels, i.e., (1) ambient (2) 50% reduction, and (3) fluctuations between reduced and ambient. In all three salinities, bacteria rapidly acquired resistance through super infection exclusion (SIE), whereby phage-infected cells acquired immunity at the cost of reduced growth. Over time, SIE was gradually replaced by evolutionary fitter surface receptor mutants (SRM). This replacement was significantly faster at ambient and fluctuating conditions compared to the low saline environment. Our experimentally parameterized mathematical model explains that suboptimal environmental conditions, in which bacterial growth is slower, slow down phage resistance evolution ultimately prolonging phage epidemics. Our results imply that, if filamentous phages encode virulence genes, these may persist longer in bacterial populations at sub-optimal environmental conditions, which, in times of climate change, are becoming more frequent. Thus, our future ocean may favour the emergence of phage-born pathogenic bacteria, and impose a greater risk for disease outbreaks, impacting not only marine animals but also humans.

evolutionary biology↗

bioRxiv2022

A comparative analysis of the ontogeny of syngnathids (pipefishes & seahorses) reveals how heterochrony contributed to their diversification

BackgroundSyngnathids are a highly derived and diverse fish clade comprising the pipefishes, pipe-horses and seahorses. They are characterized by a plethora of iconic traits that increasingly capture the attention of biologists, including geneticists, ecologists and developmental biologists. The current understanding of the origins of their derived body plan is, however, hampered by incomplete and limited descriptions of the early syngnathid ontogeny. ResultsWe provide a comprehensive description of the development of Nerophis ophidion, Syngnathus typhle, Hippocampus erectus from early cleavage stages to release from the male brooding organ and beyond, including juvenile development. We comparatively describe skeletogenesis with a particular focus on dermal bony plates, the snout-like jaw morphology, and appendages. ConclusionsThis most comprehensive and detailed account of syngnathid development to date suggests that convergent phenotypes (e.g. reduction and loss of the caudal fins), likely arose by distinct ontogenetic means in pipefish and seahorses. Comparison of the ontogenetic trajectories of S. typhle and H. erectus provides indications that characteristic features of the seahorse body plan result from developmental truncation. Altogether this work provides a valuable resource and framework for future research to understand the evolution of the outlandish syngnathid morphology from a developmental perspective. Bullet pointsO_LISyngnathids (pipefish, pipe-horses and seahorses) are a highly derived and diverse fish taxon and many of their most iconic traits - and these traits variation across species - develop during their early ontogeny. C_LIO_LIThis study provides a detailed description and staging table of the entire pre-release development (and beyond) of three distinct syngnathids (two phylogenetically distinct pipefishes and a seahorse) with a focus on the skeletal elements forming the cranium, axial skeleton, appendages and the plate armor. C_LIO_LIThe data provided in this study suggests that developmental heterochrony, i.e. alterations in the rate and timing of developmental processes between lineages, might be a central evolutionary process shaping the morphological diversity found in syngnathids today. C_LI

developmental biology↗

bioRxiv2021

HIGH VIRULENCE SELECTS FOR FAST HOST RESISTANCE EVOLUTION

Parasites and pathogens vary strikingly in their virulence and the resulting selection they impose on their hosts. While the evolution of different virulence levels is well studied, the evolution of host resistance in response to different virulence levels is less understood and as of now mainly based on observations and theoretical predictions with few experimental tests. Increased virulence can increase selection for host resistance evolution if resistance costs are outweighed by the benefits of avoiding infection. To test this, we experimentally evolved the bacterium Vibrio alginolyticus in the presence of two variants of the filamentous phage, VALG{Phi}8, that differ in their virulence. The bacterial host exhibited two alternative defence strategies against future phage infection: (1) super infection exclusion (SIE) whereby phage-infected cells were immune to subsequent infection at a cost of reduced growth, and (2) surface receptor mutations (SRM) in genes encoding the MSHA type-IV pilus providing resistance to infection by preventing phage attachment. While SIE emerged rapidly against both phages, SRM evolved faster against the high virulence compared to the low virulence phage. Using a mathematical model of our system we show that increasing virulence strengthens selection for SRM due to the higher costs of infection suffered by SIE immune hosts. In both the experiments and the model, higher levels of SRM in the host population drove more rapid phage extinction. Thus, by accelerating the evolution of host resistance, more virulent phages caused shorter epidemics.

evolutionary biology↗

bioRxiv2020

Pipefish locally adapted to low salinity in the Baltic Sea retain phenotypic plasticity to cope with ancestral salinity levels.

Genetic adaptation and phenotypic plasticity facilitate the invasion of new habitats and enable organisms to cope with a rapidly changing environment. In contrast to genetic adaptation that spans multiple generations as an evolutionary process, phenotypic plasticity allows acclimation within the life-time of an organism. Genetic adaptation and phenotypic plasticity are usually studied in isolation, however, only by including their interactive impact, we can understand acclimation and adaptation in nature. We aimed to explore the contribution of adaptation and plasticity in coping with an abiotic (salinity) and a biotic (Vibrio bacteria) stressor using six different populations of the broad-nosed pipefish Syngnathus typhle that originated from either high or low saline environments. We hypothesized that wild S. typhle populations are locally adapted to the salinity and prevailing pathogens of their native environment, and that short-term acclimation of parents to a novel salinity may aid in buffering offspring phenotypes in a matching environment. To test these hypotheses, we exposed all wild caught animals, to either high or low salinity, representing native and novel salinity conditions and allowed animals to mate. After male pregnancy, offspring was split and each half was exposed to one of the two salinities and infected with Vibrio alginolyticus bacteria that were evolved at either of the two salinities in a fully reciprocal design. We investigated life history traits of fathers (offspring survival, offspring size) and expression of 47 target genes in mothers and offspring. Pregnant males originating from high salinity exposed to low salinity were highly susceptible to opportunistic fungi infections resulting in decreased offspring size and number. In contrast, no signs of fungal infection were identified in fathers originating from low saline conditions suggesting that genetic adaptation has the potential to overcome the challenging conditions of low salinity. Genetic adaptation increased survival rates of juveniles from parents in lower salinity (in contrast to those from high salinity). Juvenile gene expression indicated patterns of local adaptation, trans-generational plasticity and developmental plasticity. The results of our study suggest that pipefish locally adapted to low salinity retain phenotypic plasticity, which allows them to also cope with ancestral salinity levels and prevailing pathogens.

evolutionary biology↗