Abstract text: Brown algae and plants share convergent traits such as the evolution of multicellularity and a polysaccharide-rich cell wall. However, considering their phylogenetic distances, the composition of their cell walls differs markedly. Brown algal cell walls are made of alginates and fucose-containing sulphated polysaccharides (FCSPs), both playing crucial roles during algal development [1]. FCSPs feature structural variations at the taxonomic level, notably between the Fucales and Laminariales. The later encompass kelp cultivars, sea-farmed on a commercial-scale worldwide, with alginates and FCSPs being top value-added products. While alginates are well described at the biochemical level, less is known regarding the chemical diversity of FCSPs. Likewise, the knowledge on the spatial organisation and interactions of these polysaccharides in tissues is limited, impairing progress in understanding basic biology in these organisms. Immunohistochemical techniques remain a powerful approach to locate polysaccharides in situ, yet molecular probes targeting FCSPs are scarce. We produced in the past brown algal monoclonal (BAM) antibodies specific for alginates (BAM6-10) [2] and FCSPs from Fucales (BAM1-4) [3]. Here we present the generation and characterisation of three monoclonal antibodies towards kelp-FSCPs. They are used in imaging studies and in medium-throughput screening to elucidate FCSP interactions in cell walls from cultivated species.

[1] Mazéas et al. (2023). Seminars in Cell & Developmental Biology 134, 112-124.

[2] Torode et al. (2016). Journal of Experimental Botany 67, 6089-6100.

[3] Torode,et al. (2015). PLoS One 10, e0118366.