Kim Hocheol, Jo Jihoon, Yang Ji Hyun, Ettahi Khaoula, Jeon Yukyoung, Yu Jundong, Bhattacharya Debashish, Kwak Jong Hwan, Yoon Hwan Su
Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Korea.
Division of Genetic Resources, Honam National Institute of Biological Resources, Mokpo 58762, Korea.
Genome Biol Evol. 2025 Apr 30;17(5). doi: 10.1093/gbe/evaf084.
Sargassum fusiforme and Sargassum thunbergii are ecologically and commercially important seaweeds that thrive in intertidal zones and are frequently exposed to extreme variation in environmental stress. Despite their importance, limited genomic information exists for these species, which hinders a comprehensive understanding of the evolution and adaptation of the genus Sargassum to marine coastal habitats. Two Sargassum genomes were generated in this study. The genome sizes of S. fusiforme and S. thunbergii were 438 and 376 Mbp, respectively, which are larger than the published genomes of the brown seaweed group, Ectocarpales. Expansion of the Sargassum genomes was significantly explained by the spread of transposable elements (TEs). Additionally, extensive gene duplications and their diversification occurred particularly through tandem, proximal, and dispersed duplications, which likely played an important role in response to environmental stress. Differentially expressed gene analysis under ambient and desiccation stress conditions confirmed that some duplicated genes respond to stress. We identified enhanced disease susceptibility 1 (EDS1) genes that promote salicylic acid (SA) biosynthesis, and their expansion is likely linked to TEs. We also confirmed the potential role of EDS1 by analyzing its subcellular localization (in Arabidopsis thaliana) and quantified the increased SA levels under desiccation conditions. This study demonstrates that the genomic evolution has played a critical role in allowing S. fusiforme and S. thunbergii to adapt to harsh intertidal conditions. The genomic resources of Sargassum species provided here will be instrumental in advancing future research, aiding in the understanding of adaptive evolution in brown algae.
羊栖菜和鼠尾藻是具有重要生态和商业价值的海藻，它们生长在潮间带，经常面临环境压力的极端变化。尽管它们很重要，但关于这些物种的基因组信息有限，这阻碍了对马尾藻属向海洋海岸栖息地进化和适应的全面理解。本研究生成了两个马尾藻基因组。羊栖菜和鼠尾藻的基因组大小分别为438和376兆碱基对，大于已发表的褐藻纲海带目的基因组。马尾藻基因组的扩张主要是由转座元件（TEs）的扩散所导致的。此外，广泛的基因重复及其多样化尤其通过串联、近端和分散重复发生，这可能在应对环境压力中发挥了重要作用。在环境和干燥胁迫条件下的差异表达基因分析证实，一些重复基因对胁迫有反应。我们鉴定出促进水杨酸（SA）生物合成的增强型疾病易感性1（EDS1）基因，其扩张可能与TEs有关。我们还通过分析其亚细胞定位（在拟南芥中）证实了EDS1的潜在作用，并量化了干燥条件下SA水平的增加。这项研究表明，基因组进化在使羊栖菜和鼠尾藻适应恶劣的潮间带条件方面发挥了关键作用。这里提供的马尾藻物种的基因组资源将有助于推进未来的研究，有助于理解褐藻的适应性进化。
