Genomic detection of domoic acid biosynthesis uncovers expanded toxigenic diversity across Pseudo-nitzschia diatoms
Year: 2026
Type: preprint
Abstract: Domoic acid (DA) production by diatom genus Pseudo-nitzschia causes recurrent harmful algal blooms with major consequences for marine ecosystems, fisheries, and human health. Predicting DA risk remains challenging because toxin production varies across morphologically similar and cryptic lineages. Consequently, morphology or single marker genes often fail to resolve toxigenic potential. Here, we expand genomic resources for Pseudo-nitzschia by generating and compiling high-quality genomes spanning diverse species and biogeographic origins, establishing a genus-wide phylogenomic framework to investigate the distribution and evolution of the DA biosynthesis ( dab ) gene cluster. Among chemically characterized strains, the dab pathway was detected in species only with confirmed DA production. While the cluster exhibits a conserved core structure, several lineages display signatures of ongoing evolution, including intronization, locus rearrangement, and pseudogenization. One striking example of dab variation occurs in toxigenic P. australis strains, in which its biochemically validated isodomoic acid A synthase-encoding gene dabC is located outside the dab locus. Metatranscriptomic surveys reveal widespread environmental dab expression across size classes and species, implicating taxa not typically associated with environmental DA events, such as P . cf. obtusa and P . cf. plurisecta . To connect dab expression with chemical output, nutrient limitation experiments in the historically inconsistent DA producer P. pseudodelicatissima combined transcriptional profiling and nontargeted metabolomics demonstrating coordinated dab expression across distinct co-expression modules and DA accumulation in response to silicon limitation. Together, these results refine the phylogenetic scope of DA production and provide a genome-resolved basis for improved molecular monitoring of toxigenic diversity.
Authors: Steffaney M. Wood-Rocca, Zoltán Füssy, Monica Thukral, Andres Mauricio Caraballo-Rodriguez, Hong Zheng, Shelly A. Wanamaker, Jennifer M. Polinski, Alexandra DeSmidt, Nathalie Choisne, Brian D. Bill, Hannah McGrath, Freya Hammar, Florian Maumus, Katherine A. Hubbard, Pieter C. Dorrestein, Tom O. Delmont, Matthew J. Harke, Bradley S. Moore, Andrew E. Allen
Institutions: J. Craig Venter Institute, Scripps Institution of Oceanography, University of California San Diego, University of Washington, Gloucester Marine Genomics Institute, Florida Fish and Wildlife Conservation Commission, AgroParisTech, Université Paris-Saclay, Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, Institut Jean-Pierre Bourgin, National Oceanic and Atmospheric Administration, NOAA National Marine Fisheries Service Northwest Fisheries Science Center, Moss Landing Marine Laboratories, Centre National de la Recherche Scientifique, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Génomique Métabolique du Genoscope, Genoscope
Language: English
Subfield: Environmental Chemistry
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7224091389