In order to elucidate the mechanism of desiccation-stress adaptability in Sargassum thunbergii,the molecular responsive process under desiccation stress was studied on the level of gene expression using the RNA-seq technology.A total of 17 532 085 and 14 479 820 clean reads were obtained in the control group CO1 and in the treatment group DR2(3 h desiccation stress)respectively,and 20 966 and 20 588 genes were detected in CO1 and DR2,respectively.A total of 476 genes were expressed differently between CO1 and DR2,among which 135(28.36%)and 341(71.64%)were respectively up-and down-regulated expressed in DR2 compared to CO1.Gene Ontology(GO)enrichment analysis assigned the 476 differently expressed genes(DEG)to 915 GO terms,among which 143 GO terms containing the up-regulated genes while 860 GO terms containing down-regulated genes.Pathway enrichment analysis showed 104 pathways were enriched.The up-regulated genes were involved in 10 pathways,whereas the down-regulated gens were involved in 101 pathways.The DEGs code the Hsp family,antioxidant enzyme system,protein synthesis,process and degradation related factors and so on.The above results indicated that the response process to desiccation stress in S.thunbergii was complex,involving many metabolic pathways and signal transduction pathways.