Abstract: In order to research the response mechanism of Dunaliella polymorpha under different light stresses, screen differentially expressed genes, and analyze their functions and metabolic pathways, the shading control group, medium light intensity stress group and high light intensity stress group were set up respectively based on the mature algae strains. The analyses were performed by utilizing morphological, fluorescence parameter determination, high-throughput sequencing and bioinformatics methods at the cellular, biochemical and transcriptomic levels, respectively.A total of 52853 unigenes with 29025 coding domain sequences (CDSs) from the nine RNA-seq libraries were obtained in this alga. 41.59% of unigenes were annotated in the 7 bio-database. Moreover, a total of 282 contigs were de novo assembled with a 1072 bp N50 and a GC percentage of 52.25%.Furthermore, based on the differentially expressed genes (DEGs), the medium light intensity stress group and high light intensity stress group could be clusted together and the number of down-regulated DEGs (9385) was more than that of the up-regulated ones (8046). The GO and KEGG pathway analyses of the intergroup common DEGs showed that the functions of key genes involved in the light stress response were mainly related to the intracellular photosynthetic catalytic activity and antenna protein synthesis. The main metabolic pathways were related to the metabolic process stimulated by the light intensity. The results laid a foundation for further researching on this algal photosynthetic mechanism, cloning and expression of key photosynthetic regulation genes, molecular breeding and their industrial application in future.

Key words: Dunaliella polymorpha, transcriptomic analysis, light intensity, differentially expressed genes