Browsing by Author "Bartsch, Inka"
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- Corrigendum: Imprint of climate change on Pan-Arctic marine vegetationPublication . Krause-Jensen, Dorte; Archambault, Philippe; Assis, Jorge; Bartsch, Inka; Bischof, Kai; Filbee-Dexter, Karen; Dunton, Kenneth H.; Maximova, Olga; Ragnarsdóttir, Sunna Björk; Sejr, Mikael K.; Simakova, Uliana; Spiridonov, Vassily; Wegeberg, Susse; Winding, Mie H. S.; Duarte, Carlos M.In the original article, there were mistakes in Tables 2–4 and associated legends and text as published. The original article contained errors in the reported modeled macroalgal distribution area in the pan-Arctic and its subregions because the polygons used to calculate the areas were not correctly defined. A correction has been made to Tables 2–4 and their associated legends: The Table legends missed the word “brown” and an explanatory note. The corrected Tables 2–4 and associated legends appear below (corrections marked in bold).
- A European biobanking strategy for safeguarding macroalgal genetic material to ensure food security, biosecurity and conservation of biodiversityPublication . Hofmann, Laurie C.; Brakel, Janina; Bartsch, Inka; Arismendi, Gabriel Montecinos; Bermejo, Ricardo; Parente, Manuela I.; Creis, Emeline; Clerck, Olivier De; Jacquemin, Bertrand; Knoop, Jessica; Lorenz, Maike; Machado, Levi Pompermayer; Orfanidis, Sotiris; Probert, Ian; Menendez, , Cecilia Rad; Ross, Michael; Rautenberger, Ralf; Schiller, Jessica; Serrao, Ester A.; Steinhagen, Sophie; Sulpice, Ronan; Valero, Myriam; Wichard, Thomas; Serrao, Ester A.; Martins, neuzaBiobanking (also known as germplasm banking) of genetic material is a well-established concept for preserving plant genetic diversity and also contributes to food security, conservation and restoration. Macroalgae currently represent a very small percentage of the strains in publicly accessible European germplasm banks, despite the increasing recognition of their contribution to achieving several of the United Nations Sustainable Development Goals. There is no strategic coordination of existing macroalgal strains, which could have severe ecological and economic implications as species and their genetic diversity disappear rapidly due to local and global environmental stressors. In this opinion paper, we stress the importance of a coordinated European effort for preserving macroalgal genetic diversity and suggest the development of a three-pillared system to safeguard European macroalgal genetic material consisting of (1) a European Board of Macroalgal Genetic Resources (EBMGR) to provide supervision, support and coordination, (2) a network of germplasm banks consisting of currently existing and newly established infrastructures and (3) an interoperable databank integrating existing databanks. While it will be the task of the EBMGR to identify and coordinate priorities, we offer initial recommendations for preserving macroalgal genetic material, discuss the risks of inaction, and highlight the challenges that must be overcome.
- Heat stress responses and population genetics of the kelp Laminaria digitata (Phaeophyceae) across latitudes reveal differentiation among North Atlantic populationsPublication . Liesner, Daniel; Fouqueau, Louise; Valero, Myriam; Roleda, Michael Y.; Pearson, Gareth; Bischof, Kai; Valentin, Klaus; Bartsch, InkaTo understand the thermal plasticity of a coastal foundation species across its latitudinal distribution, we assess physiological responses to high temperature stress in the kelp Laminaria digitata in combination with population genetic characteristics and relate heat resilience to genetic features and phylogeography. We hypothesize that populations from Arctic and cold-temperate locations are less heat resilient than populations from warm distributional edges. Using meristems of natural L. digitata populations from six locations ranging between Kongsfjorden, Spitsbergen (79°N), and Quiberon, France (47°N), we performed a common-garden heat stress experiment applying 15°C to 23°C over eight days. We assessed growth, photosynthetic quantum yield, carbon and nitrogen storage, and xanthophyll pigment contents as response traits. Population connectivity and genetic diversity were analyzed with microsatellite markers. Results from the heat stress experiment suggest that the upper temperature limit of L. digitata is nearly identical across its distribution range, but subtle differences in growth and stress responses were revealed for three populations from the species' ecological range margins. Two populations at the species' warm distribution limit showed higher temperature tolerance compared to other populations in growth at 19°C and recovery from 21°C (Quiberon, France), and photosynthetic quantum yield and xanthophyll pigment responses at 23°C (Helgoland, Germany). In L. digitata from the northernmost population (Spitsbergen, Norway), quantum yield indicated the highest heat sensitivity. Microsatellite genotyping revealed all sampled populations to be genetically distinct, with a strong hierarchical structure between southern and northern clades. Genetic diversity was lowest in the isolated population of the North Sea island of Helgoland and highest in Roscoff in the English Channel. All together, these results support the hypothesis of moderate local differentiation across L. digitata's European distribution, whereas effects are likely too weak to ameliorate the species' capacity to withstand ocean warming and marine heatwaves at the southern range edge.
- Hybrid vigour for thermal tolerance in hybrids between the allopatric kelps Laminaria digitata and L. pallida (Laminariales, Phaeophyceae) with contrasting thermal affinitiesPublication . Martins, Neusa; Pearson, Gareth; Gouveia, Licínia; Tavares, Ana I; Serrao, Ester; Bartsch, InkaKelps are globally important bioengineering species with high ecological and economic value, but are increasingly threatened by climate-driven geographic range shifts. The inheritance of economically important traits from parents to offspring is poorly understood in kelps but it is of utmost interest to seaweed farmers wishing to select strains with superior performance and resilience to environmental change. For two allopatric kelp species (N-Atlantic Laminaria digitata and S-Atlantic L. pallida), we compared the speed of gametogenesis and reproductive success in parental gametophytes, and produced intraspecific and reciprocal interspecific crosses of female × male gametophyte parents isolated from the two species. We then compared the upper thermal resilience of microscopic and macroscopic sibling sporophytes in an exposure experiment over two weeks. The upper thermal limit of the sporophytes resulting from intraspecific crosses of the two species deviated by 1°C. In contrast, sporophytes from both interspecific hybrid crosses had a 2–3°C higher upper thermal tolerance than single species sporophytes, indicating heterosis for thermal tolerance. This phenotypic response appears partially sex-dependent in our study, with female parents being more important in determining the thermal-response phenotype than male parents. The presence of male gametophytes generally enhanced female reproductive success. Both gametogenesis rate and reproductive success differed among the types of reciprocal crosses. Although the interspecific crosses were artificial in an ecological sense, they may provide a tool for understanding the molecular basis of heterosis and thermal tolerance in kelps (e.g. by investigating species-specific gene expression), or for aquaculture breeding programmes against a background of rapid environmental change.
- Hybrid vigour for thermal tolerance in hybrids between the allopatric kelps Laminaria digitata and L. pallida (Laminariales, Phaeophyceae) with contrasting thermal affinitiesPublication . Martins, Neusa; Pearson, Gareth; Gouveia, Licínia; Tavares, Ana I; Serrao, Ester; Bartsch, InkaKelps are globally important bioengineering species with high ecological and economic value, but are increasingly threatened by climate-driven geographic range shifts. The inheritance of economically important traits from parents to offspring is poorly understood in kelps but it is of utmost interest to seaweed farmers wishing to select strains with superior performance and resilience to environmental change. For two allopatric kelp species (N-Atlantic Laminaria digitata and S-Atlantic L. pallida), we compared the speed of gametogenesis and reproductive success in parental gametophytes, and produced intraspecific and reciprocal interspecific crosses of female x male gametophyte parents isolated from the two species. We then compared the upper thermal resilience of microscopic and macroscopic sibling sporophytes in an exposure experiment over two weeks. The upper thermal limit of the sporophytes resulting from intraspecific crosses of the two species deviated by 1 degrees C. In contrast, sporophytes from both interspecific hybrid crosses had a 2-3 degrees C higher upper thermal tolerance than single species sporophytes, indicating heterosis for thermal tolerance. This phenotypic response appears partially sex-dependent in our study, with female parents being more important in determining the thermal-response phenotype than male parents. The presence of male gametophytes generally enhanced female reproductive success. Both gametogenesis rate and reproductive success differed among the types of reciprocal crosses. Although the interspecific crosses were artificial in an ecological sense, they may provide a tool for understanding the molecular basis of heterosis and thermal tolerance in kelps (e.g. by investigating species-specific gene expression), or for aquaculture breeding programmes against a background of rapid environmental change.
- Increased heat resilience of intraspecific outbred compared to inbred lineages in the Kelp Laminaria digitata: physiology and transcriptomicsPublication . Liesner, Daniel; Pearson, Gareth Anthony; Bartsch, Inka; Rana, Shivani; Harms, Lars; Heinrich, Sandra; Bischof, Kai; Glöckner, Gernot; Valentin, KlausMarine forests and kelps as their foundation species are threatened by ocean warming especially at the warm distributional edges. Previously identified genetic divergence and ecotypic differentiation within kelp species may allow to produce more resilient lineages by intraspecific outbreeding among populations. In a mechanistic investigation of heat stress, heterosis (hybrid vigour), and underlying gene expression patterns, we assessed the thermal performance of inbred (selfings) and outbred (reciprocal crosses) sporophytes of the N-Atlantic kelp Laminaria digitata among clonal isolates from two divergent populations; one from the temperate North Sea (Helgoland) and one from the Arctic (Spitsbergen). First, we investigated the upper thermal tolerance of microscopic sporophytes in a 14-day experiment applying sublethal to lethal 20-23 degrees C. The upper survival temperature of microscopic sporophytes was lower for the inbred Arctic selfing (21 degrees C) than for the temperate selfing and the reciprocal crosses (22 degrees C). Only in the temperate selfing, 4.5% of sporophytes survived 23 degrees C. We then subjected 4-7 cm long sporophytes to a control temperature (10 degrees C), moderate (19 degrees C) and sublethal to lethal heat stress (20.5 degrees C) for 18 days to assess gene expression in addition to physiological parameters. Growth and optimum quantum yield decreased similarly in the reciprocal crosses and the temperate selfing at 19 and 20.5 degrees C, while inbred Arctic sporophytes died within seven days at both 19 and 20.5 degrees C. In response to 20.5 degrees C, 252 genes were constitutively regulated across all surviving lineages, which we use to describe metabolic regulation patterns in response to heat stress in kelp. At sublethal 20.5 degrees C, ca. 150 genes were differentially expressed by either crossed lineage in comparison to the temperate selfing, indicating that they maintained a growth response similar to the temperate selfing with differential metabolic regulation during sublethal heat stress. Subtle differences in physiology and the differential expression of nine genes between the reciprocal crosses at 20.5 degrees C indicate that female and male gametophytes may contribute differently to offspring traits. We consider potential inbreeding depression in the Spitsbergen selfing and quantify the better performance of both crosses using heterosis-related parameters. We discuss the potential and risks of outbreeding to produce more resilient crops for mariculture and marine forest restoration.
- Interactions of daylength, temperature and nutrients affect thresholds for life stage transitions in the kelp Laminaria digitata (Phaeophyceae)Publication . Martins, Neusa; Tanttu, Heidi; Pearson, Gareth; Serrao, Ester A.; Bartsch, InkaKelp beds worldwide are under pressure from ongoing climate and environmental change. Along European coastlines increases in seawater temperature and changes in nutrient conditions occur where upwelling events are disrupted and also along eutrophicated coasts. In addition, seaweed responses to change may interact with seasonal daylength cycles. We performed a factorial experiment to examine the combined effects of seawater temperatures, nutrient regimes and photoperiod (long and short days) in order to better understand how latitudinal or seasonal differences in daylengths affect the sensitivity of transient microscopic kelp stages of Laminaria digitata from the North Sea to warming and eutrophication. While the optimal temperature range for vegetative gametophyte growth was 10 degrees C-18 degrees C under long summer photoperiod conditions, gametogenesis was induced at lower temperatures between 5 degrees C and 15 degrees C, with maximum sporophyte development under long photoperiods and enriched nutrient regimes, which represent local late spring conditions. Although gametogenesis was fastest at 10 degrees C-15 degrees C, sporophyte recruitment was highest at 5 degrees C. As these particular early life cycle processes in L. digitata have different temperature optima, this may drive the seasonal cycle of recruitment in the field. Increasing summer temperatures due to global warming will increase gametophyte size due to enhanced vegetative growth and inhibition of gametogenesis. This will probably lead to delayed but enhanced recruitment of new sporophytes under cooler autumn to spring conditions over a wide geographical scale, preventing the formation of juvenile sporophytes under stressful summer conditions and possibly changing annual recruitment patterns.
- Microscopic life stages of Arctic kelp differ in their resilience and reproductive output in response to Arctic seasonalityPublication . Silva, Cláudio Figueira; Pearson, Gareth; Serrao, Ester; Bartsch, Inka; Martins, NeusaKelp forests are important habitats in the strongly environmentally and seasonally variable Arctic. There is a critical lack of knowledge about how seasonal conditions and climate change scenarios influence survival and reproduction of kelp early life stages. To better understand the regulation of kelp life cycle processes in this harsh environment we focused on the physiological performance and reproductive success of early life stages in Alaria esculenta and Laminaria digitata from Kongsfjorden, Spitsbergen. Gametophyte growth and survival during Arctic winter and subsequent sporophyte recruitment under spring conditions were investigated. Winter conditions (2 degrees C, complete darkness) halted gametophyte growth and prevented the onset of gametogenesis in both species. The gametophytes of L. digitata but not A. esculenta became fertile after returning to spring conditions, suggesting that sporogenesis, sexual reproduction and recruitment in A. esculenta must occur successively during summer/autumn while in L. digitata a new generation of sporophytes could develop from over-wintering gametophytes. The effects of simulated canopy shading (offering protection against extreme irradiance stress, particularly as sea ice retreats), present-day and projected Arctic summer seawater temperatures, and nutrient levels on gametophyte survival, fertility and sporophyte recruitment success were also investigated in both species. A. esculenta gametophytes had greater survival and reproductive success than L. digitata, except under very low light (simulating dense canopy). In contrast, shading was required for reproductive success in L. digitata gametophytes. Predicted summer temperatures of 9 degrees C reduced sexual reproduction in both species. Interactions observed between these environmental drivers probably reflect species-specific seasonal patterns of survival and reproduction. These differences between kelp species in response to abiotic factors and light levels (simulated canopy shading) suggest that climate change could alter community structure in the Arctic through effects on sexual reproduction and sporophyte recruitment success. HIGHLIGHTS center dot Gametophytes were able to endure long periods of darkness.center dot Parental kelp canopy is key for gametophyte survival and recruitment.center dot Climate change may alter kelp recruitment patterns.
- Sex-dependent and-independent transcriptional changes during haploid phase gametogenesis in the sugar kelp Saccharina latissimaPublication . Pearson, Gareth; Martins, Neusa; Madeira, Pedro M.; Serrao, Ester; Bartsch, InkaIn haplodiplontic lineages, sexual reproduction occurs in haploid parents without meiosis. Although widespread in multicellular lineages such as brown algae (Phaeophyceae), haplodiplontic gametogenesis has been little studied at the molecular level. We addressed this by generating an annotated reference transcriptome for the gametophytic phase of the sugar kelp, Saccharina latissima. Transcriptional profiles of microscopic male and female gametophytes were analysed at four time points during the transition from vegetative growth to gametogenesis. Gametogenic signals resulting from a switch in culture irradiance from red to white light activated a core set of genes in a sex-independent manner, involving rapid activation of ribosome biogenesis, transcription and translation related pathways, with several acting at the post-transcriptional or post-translational level. Additional genes regulating nutrient acquisition and key carbohydrate-energy pathways were also identified. Candidate sex-biased genes under gametogenic conditions had potentially key roles in controlling female- and male-specific gametogenesis. Among these were several sex-biased or -specific E3 ubiquitin-protein ligases that may have important regulatory roles. Females specifically expressed several genes that coordinate gene expression and/or protein degradation, and the synthesis of inositol-containing compounds. Other female-biased genes supported parallels with oogenesis in divergent multicellular lineages, in particular reactive oxygen signalling via an NADPH-oxidase. Males specifically expressed the hypothesised brown algal sex-determining factor. Male-biased expression mainly involved upregulation of genes that control mitotic cell proliferation and spermatogenesis in other systems, as well as multiple flagella-related genes. Our data and results enhance genome-level understanding of gametogenesis in this ecologically and economically important multicellular lineage.
- Thermal traits for reproduction and recruitment differ between Arctic and Atlantic kelp Laminaria digitataPublication . Martins, Neusa; Pearson, Gareth; Bernard, Julien; Serrao, Ester; Bartsch, InkaThe plasticity of different kelp populations to heat stress has seldom been investigated excluding environmental effects due to thermal histories, by raising a generation under common garden conditions. Comparisons of populations in the absence of environmental effects allow unbiased quantification of the meta-population adaptive potential and resolution of population-specific differentiation. Following this approach, we tested the hypothesis that genetically distinct arctic and temperate kelp exhibit different thermal phenotypes, by comparing the capacity of their microscopic life stages to recover from elevated temperatures. Gametophytes of Laminaria digitata (Arctic and North Sea) grown at 15°C for 3 years were subjected to common garden conditions with static or dynamic (i.e., gradual) thermal treatments ranging between 15 and 25°C and also to darkness. Gametophyte growth and survival during thermal stress conditions, and subsequent sporophyte recruitment at two recovery temperatures (5 and 15°C), were investigated. Population-specific responses were apparent; North Sea gametophytes exhibited higher growth rates and greater sporophyte recruitment than those from the Arctic when recovering from high temperatures, revealing differential thermal adaptation. All gametophytes performed poorly after recovery from a static 8-day exposure at 22.5°C compared to the response under a dynamic thermal treatment with a peak temperature of 25°C, demonstrating the importance of gradual warming and/or acclimation time in modifying thermal limits. Recovery temperature markedly affected the capacity of gametophytes to reproduce following high temperatures, regardless of the population. Recovery at 5°C resulted in higher sporophyte production following a 15°C and 20°C static exposure, whereas recovery at 15°C was better for gametophyte exposures to static 22.5°C or dynamic heat stress to 25°C. The subtle performance differences between populations originating from sites with contrasting local in situ temperatures support our hypothesis that their thermal plasticity has diverged over evolutionary time scales.