Fucoidans: a new frontier in brown seaweed research and biotechnology.

Fucoidans, also known as fucose-containing sulfated polysaccharides (FCSPs), are abundant and structurally complex glycans found in the cell wall of brown algae. These compounds have been shown to have fundamental roles in the development and physiology of these organisms, to provide a major contribution to marine carbon sequestration, and to exhibit numerous bioactivities. Despite this, we currently have a limited understanding of the metabolic pathways and enzymes involved in synthesis and remodelling of fucoidans, their spatial and temporal dynamics in brown algae and in the marine environment, and how their structure and composition influence their bioactivities. Here, we highlight some of the challenges that have hindered progress on fucoidan research. We then moved on to underline some of the recent technical progress and new resources that would contribute to alleviate these challenges when combined together. This includes new technical approaches in analytical chemistry and glycobiology, as well the extension of genomic resources and genetics tools for brown algae. Finally, we suggest how progress in fucoidan research should contribute to advance understanding on brown algae biology, while supporting current and developing new aspects in fucoidan applications and seaweed biotechnology as part of the growing blue bioeconomy.