Deciphering the genetic basis of growth and heat tolerance in sugar kelp: a genomics-driven breeding approach

Summary

The sugar kelp Saccharina latissima is vital to coastal ecosystems and aquaculture across Europe and North America. However, rising sea temperatures cause a decline in kelp populations, requiring research efforts to enhance their heat tolerance. Meanwhile, kelp aquaculture would economically benefit from cultivars with enhanced growth. Hence, developing sugar kelp strains with improved heat tolerance and growth rate through selective breeding is of increasing interest. Here, the genetic basis of these traits was investigated by phenotyping and genotyping sugar kelp genetic lines generated by crossing clonal gametophyte cultures from a Svalbard population. We found that growth is more maternally inherited than heat tolerance. Heterosis arose for heat tolerance but not for growth when breeding with locally available genetic diversity. Additionally, non-genetic factors have a stronger influence in determining those traits than genetics. These findings can contribute to improve the selection of robust sugar kelp strains for aquaculture and restoration.