Global interfertility and heterosis in sugar kelp populations: a next step in sugar kelp breeding

The potential of seaweed aquaculture is restricted by high labor, production and processing costs, leading to low economic viability. Selective breeding can improve yields and cultivation efficiency, thereby decreasing production costs. Until now, genetic resources as input for Saccharina latissima breeding trials have been sourced strictly locally, due to concerns regarding outplanting genetically exogenous material in local waters. Here we study, for the first time, worldwide interregional fertility of the seaweed S. latissima, in order to assess the potential of including global S. latissima genetic resources for selective breeding with regard to heterosis. We quantified the yield (as an indicative aquacultural performance) and morphological traits of intra- and interregional S. latissima hybrids originating from a broad range of locations in a common garden experiment. Our results show that the practical application of worldwide S. latissima genetic resources in breeding programs is feasible based on global interfertility. We found a wide morphological diversity of hybrids and observed significant heterosis in interregional hybrids. The degree of heterosis could not be linked to geographic distance. These findings reveal that worldwide genetic resources can considerably contribute to S. latissima breeding programs and could offer a major next step in improving yields and quality traits.

The online version contains supplementary material available at 10.1007/s10811-025-03447-7.