Integrated transcriptomic and proteomic analysis unravels the response mechanisms of Saccharina japonica to heat stress

High temperature is a major abiotic stress that limits the growth and productivity of seaweed. Over the past decades, the cold-temperate seaweed Saccharina japonica has been domesticated and gradually adapted to subtropical regions with higher temperatures. However, there is limited knowledge regarding the molecular responses of S. japonica to heat stress. In this study, an integrated transcriptomic and proteomic analysis was performed to explore the molecular mechanism underlying the response to heat stress in S. japonica. A total of 6777 genes and 226 proteins were identified that exhibited differential expression in heat stress samples comparison to non-stress sample. GO analysis revealed that the GO molecular function (MF) terms related to unfolded protein binding/protein binding, and heat shock protein (HSP) binding/HSP90 binding were significantly enriched in the up-regulated DEGs/DEPs in S. japonica sporophytes under heat stress. Further analysis of the global gene and protein expression profiles unveiled the potential mechanisms in S. japonica to alleviate heat stress through up-regulation of the heat stress transcription factor-heat shock proteins-HSP70/HSP90 organising proteins (HSF-HSPs-HOPs) module, down-regulation of reactive oxygen species (ROS) generation and up-regulation of ROS scavenging. Our results provide novel insights into the heat stress acclimation mechanism in S. japonica, and would benefit future selection of heat-tolerant varieties.