Differences by origin in methylome suggest eco-phenotypes in the kelp Saccharina latissima

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The sugar kelp Saccharina latissima I: recent advances in a changing climate

• Background: The sugar kelp Saccharina latissima is a Laminariales species widely distributed in the Northern Hemisphere. Its physiology and ecology have been studied since the 1960s, given its ecological relevance on western temperate coasts. However, research interest has been rising recently, driven mainly by reports of negative impacts of anthropogenically induced environmental change and by the increased commercial interest in cultivating the species, with several industrial applications for the resulting biomass. • Scope: We used a variety of sources published between 2009 to May 2023 (but including some earlier literature where required), to provide a comprehensive review of the ecology, physiology, biochemical and molecular biology of S. latissima. In so doing we aimed to better understand the species’ response to stressors in natural communities, but also inform the sustainable cultivation of the species. • Conclusion: Due to its wide distribution, S. latissima has developed a variety of physiological and biochemical mechanisms to adjust to environmental changes, including adjustments in photosynthetic parameters, modulation of osmolytes and antioxidants, reprogramming of gene expression and epigenetic modifications, among others summarized in this review. This is particularly important because massive changes in the abundance and distribution of S. latissima have already been observed. Namely, presence and abundance of S. latissima has significantly decreased at the rear edges on both sides of the Atlantic, and increased in abundance at the polar regions. These changes were mainly caused by climate change and will therefore be increasingly evident in the future. Recent developments in genomics, transcriptomics and epigenomics have clarified the existence of genetic differentiation along its distributional range with implications in the fitness at some locations. The complex biotic and abiotic interactions unraveled here demonstrated the cascading effects the disappearance of a kelp forest can have in a marine ecosystem. We show how S. latissima is an excellent model to study acclimation and adaptation to environmental variability and how to predict future distribution and persistence under climate change.publishedVersio

The sugar kelp Saccharina latissima II: Recent advances in farming and application

The sugar kelp Saccharina latissima has received intense scientific attention over the last decades. In recent years, interest in cultivation of the species has strongly increased in the North Atlantic Ocean and the Eastern Pacific Ocean, driven by the great potential of S. latissima to be utilised for various industrial applications, including food, feed, and biomaterials. Accordingly, current research has focused on improving farming methods and technology, environmental impacts, and site selection. In addition, many studies have investigated the varying chemical composition of S. latissima, extraction of commercially interesting components, and the use of the biomass and its derived components in various applications. This review provides a comprehensive overview of farming and applications of S. latissima from the last 15 years. Additional insights on other research topics, such as ecology, physiology, biochemical and molecular biology of S. latissima, are given in the first review, “The sugar kelp Saccharina latissima I: recent advances in a changing climate” (Diehl et al. 2023).publishedVersio

Chloroplast DNA methylation in the kelp Saccharina latissima is determined by origin and possibly influenced by cultivation

Abstract DNA cytosine methylation is an important epigenetic mechanism in genomic DNA. In most land plants, it is absent in the chloroplast DNA. We detected methylation in the chloroplast DNA of the kelp Saccharina latissima, a non‐model macroalgal species of high ecological and economic importance. Since the functional role of the chloroplast methylome is yet largely unknown, this fundamental research assessed the chloroplast DNA cytosine methylation in wild and laboratory raised kelp from different climatic origins (High‐Arctic at 79° N, and temperate at 54° N), and in laboratory samples from these origins raised at different temperatures (5, 10 and 15°C). Results suggest genome‐wide differences in methylated sites and methylation level between the origins, while rearing temperature had only weak effects on the chloroplast methylome. Our findings point at the importance of matching conditions to origin in restoration and cultivation processes to be valid even on plastid level

Differences by origin in methylome suggest eco-phenotypes in the kelp Saccharina latissima

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Eco-physiological data on Laminaria solidungula and Saccharina latissima from Kongsfjorden, Spitsbergen, during the polar night 2016/17

Kelps, perennial brown seaweeds of the order Laminariales, are foundational species in Arctic coastal ecosystems. Presently, their ability to persist under polar night conditions might be significantly affected by increasing winter temperatures. We assessed physiological parameters (photosynthesis, pigment content, respiration, carbohydrate storage) in two species of Arctic kelp, the boreal-temperate Saccharina latissima and the Arctic-endemic Laminaria solidungula, during the polar night 2016/17. Algae were sampled from Kongsfjorden, Svalbard, 78° 55' N, shortly before the onset of the dark period in October, and at the end of the polar night in early February. Analyses were conducted for different tissue sections along the phylloid (Meristem, Centre Region, Distal Region). Data suggest that kelp maintain their photosynthetic competence throughout the entire winter period, as indicated by PE-curve-parameters, and photosynthetic pigment contents. Overall laminarin content was reduced by 96 % in S. latissima, and by 90 % in L. solidungula during winter indicating that this storage glucan fuelled metabolic function during the polar night. Marked differences in laminarin content between the phylloid regions and across species indicated specific adaptive mechanisms between boreal-temperate and Arctic-endemic kelp. We suggest that laminarin turnover represents a sensitive parameter to assess kelp physiology under a changing temperature regime