Available online: explore our new platform for high-efficiency, transgene-free CRISPR genome editing in brown algae. In this study, we present a robust method applicable across four ecologically and biotechnologically important brown algal species, including the kelp Undaria pinnatifida. Using a polyethylene glycol (PEG)-mediated ribonucleoprotein (RNP) delivery system, we achieve reproducible editing across multiple loci without cloning or specialized equipment. The successful transfer of the method to kelps is particularly significant given their ecological role as foundation species of coastal ecosystems and their growing importance in blue biotechnology. This platform now opens the door to functional genomics in kelps and other brown algae, providing powerful tools for investigating development, life cycle regulation, and the independent evolution of complex multicellularity.
