Percorrer por autor "Jahnke, Marlene"
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- 2b-RAD genotyping of the seagrass Cymodocea nodosa along a latitudinal cline identifies candidate genes for environmental adaptationPublication . Ruocco, Miriam; Jahnke, Marlene; Silva, João; Procaccini, Gabriele; Dattolo, EmanuelaPlant populations distributed along broad latitudinal gradients often show patterns of clinal variation in genotype and phenotype. Differences in photoperiod and temperature cues across latitudes influence major phenological events, such as timing of flowering or seed dormancy. Here, we used an array of 4,941 SNPs derived from 2b-RAD genotyping to characterize population differentiation and levels of genetic and genotypic diversity of three populations of the seagrass Cymodocea nodosa along a latitudinal gradient extending across the Atlantic-Mediterranean boundary (i.e., Gran Canaria-Canary Islands, Faro-Portugal, and Ebro Delta-Spain). Our main goal was to search for potential outlier loci that could underlie adaptive differentiation of populations across the latitudinal distribution of the species. We hypothesized that such polymorphisms could be related to variation in photoperiod-temperature regime occurring across latitudes. The three populations were clearly differentiated and exhibited diverse levels of clonality and genetic diversity. Cymodocea nodosa from the Mediterranean displayed the highest genotypic richness, while the Portuguese population had the highest clonality values. Gran Canaria exhibited the lowest genetic diversity (as observed heterozygosity). Nine SNPs were reliably identified as outliers across the three sites by two different methods (i.e., BayeScan and pcadapt), and three SNPs could be associated to specific protein-coding genes by screening available C. nodosa transcriptomes. Two SNPs-carrying contigs encoded for transcription factors, while the other one encoded for an enzyme specifically involved in the regulation of flowering time, namely Lysine-specific histone demethylase 1 homolog 2. When analyzing biological processes enriched within the whole dataset of outlier SNPs identified by at least one method, "regulation of transcription" and "signalling" were among the most represented. Our results highlight the fundamental importance signal integration and gene-regulatory networks, as well as epigenetic regulation via DNA (de)methylation, could have for enabling adaptation of seagrass populations along environmental gradients.
- m6A RNA Methylation in marine plants: first insights and relevance for biological rhythmsPublication . Ruocco, Miriam; Ambrosino, Luca; Jahnke, Marlene; Chiusano, Maria; Barrote, Isabel; Procaccini, Gabriele; Silva, João; Dattolo, EmanuelaCircadian regulations are essential for enabling organisms to synchronize physiology with environmental light-dark cycles. Post-transcriptional RNA modifications still represent an understudied level of gene expression regulation in plants, although they could play crucial roles in environmental adaptation. N6-methyl-adenosine (m6A) is the most prevalent mRNA modification, established by "writer" and "eraser" proteins. It influences the clockwork in several taxa, but only few studies have been conducted in plants and none in marine plants. Here, we provided a first inventory of m6A-related genes in seagrasses and investigated daily changes in the global RNA methylation and transcript levels of writers and erasers in Cymodocea nodosa and Zostera marina. Both species showed methylation peaks during the dark period under the same photoperiod, despite exhibiting asynchronous changes in the m6A profile and related gene expression during a 24-h cycle. At contrasting latitudes, Z. marina populations displayed overlapping daily patterns of the m6A level and related gene expression. The observed rhythms are characteristic for each species and similar in populations of the same species with different photoperiods, suggesting the existence of an endogenous circadian control. Globally, our results indicate that m6A RNA methylation could widely contribute to circadian regulation in seagrasses, potentially affecting the photo-biological behaviour of these plants.
- A Pleistocene legacy structures variation in modern seagrass ecosystemsPublication . Duffy, J. Emmett; Stachowicz, John J.; Reynolds, Pamela L.; Hovel, Kevin A.; Jahnke, Marlene; Sotka, Erik E.; Boström, Christoffer; Boyer, Katharyn E.; Cusson, Mathieu; Eklöf, Johan; Engelen, Aschwin; Eriksson, Britas Klemens; Fodrie, F. Joel; Griffin, John N.; Hereu, Clara M.; Hori, Masakazu; Hughes, A. Randall; Ivanov, Mikhail V.; Jorgensen, Pablo; Kruschel, Claudia; Lee, Kun-Seop; Lefcheck, Jonathan S.; Moksnes, Per-Olav; Nakaoka, Masahiro; O’Connor, Mary I.; O’Connor, Nessa E.; Orth, Robert J.; Peterson, Bradley J.; Reiss, Henning; Reiss, Katrin; Richardson, J. Paul; Rossi, Francesca; Ruesink, Jennifer L.; Schultz, Stewart T.; Thormar, Jonas; Tomas, Fiona; Unsworth, Richard; Voigt, Erin; Whalen, Matthew A.; Ziegler, Shelby L.; Olsen, Jeanine L.Distribution of Earth's biomes is structured by the match between climate and plant traits, which in turn shape associated communities and ecosystem processes and services. However, that climate-trait match can be disrupted by historical events, with lasting ecosystem impacts. As Earth's environment changes faster than at any time in human history, critical questions are whether and how organismal traits and ecosystems can adjust to altered conditions. We quantified the relative importance of current environmental forcing versus evolutionary history in shaping the growth form (stature and biomass) and associated community of eelgrass (Zostera marina), a widespread foundation plant of marine ecosystems along Northern Hemisphere coastlines, which experienced major shifts in distribution and genetic composition during the Pleistocene. We found that eelgrass stature and biomass retain a legacy of the Pleistocene colonization of the Atlantic from the ancestral Pacific range and of more recent within-basin bottlenecks and genetic differentiation. This evolutionary legacy in turn influences the biomass of associated algae and invertebrates that fuel coastal food webs, with effects comparable to or stronger than effects of current environmental forcing. Such historical lags in phenotypic acclimatization may constrain ecosystem adjustments to rapid anthropogenic climate change, thus altering predictions about the future functioning of ecosystems.