Dynamic profile of proteome revealed multiple levels of regulation under heat stress in Saccharina japonica

Saccharina japonica is a typical seaweed that has been domesticated and cultivated at a large scale for a long time worldwide. Compared to the wild populations, the Saccharina cultivars have significant greater high-temperature tolerance. However, the molecular mechanisms of high temperature tolerance are still unknown. This study characterized the protein expression profile under heat stress using the iTRAQ strategy integrated with transcriptome data to identify the candidate genes involved in the heat stress tolerance. A total of 104 and 107 proteins were identified as the differential expressed proteins (DEPs) in sporophyte and gametophyte, respectively. Only 14 DEPs identified both in sporophyte and gametophyte indicated that the two generations have different protein expression in response to the heat stress. The correlation between proteome and transcriptome profile under heat stress was very low, with only six genes were identified both on the transcription and protein levels. However, 23 pathways, including multiple cellular processes such as nitrogen and carbon metabolism, transcription, translation, posttranslational modification, antioxidant system etc., were identified. This study is the first exploration into the molecular mechanism of Saccharina heat tolerance on both transcriptomic and proteomic levels, which provides new insight into the regulation mechanism in response to heat stress in kelp.