Mechanisms underlining Kelp (Saccharina japonica) adaptation to relative high seawater temperature.

Saccharina japonica has been cultivated in China for almost a century. From Dalian to Fujian, the lowest and the highest seawater temperatures in the period of cultivation increased by 14℃ and 8℃, respectively. Its adaptation to elevated seawater temperature is an example of securing the natural habitats of a species. To decipher the mechanisms underlining S. japonica adaptation to relative high seawater temperature, we assembled ~ 516.3 Mb female gametophyte genome and ~ 540.3 Mb of the male, respectively. The gametophytes isolated from southern China kelp cultivars acclimated to the relative high seawater temperature by transforming amino acids, glycosylating protein, maintaining osmotic pressure, intensifying the innate immune system, and exhausting energy and reduction power through the PEP-pyruvate-oxaloacetate node and the iodine cycle. They adapted to the relative high seawater temperature by transforming amino acids, changing sugar metabolism and intensifying innate immune system. The sex of S. japonica was determined by HMG-sex, and around this male gametophyte determiner the stress tolerant genes become linked to or associated with.