Transcriptomic analysis of Haematococcus lacustris during astaxanthin accumulation under high irradiance and nutrient starvation

In this study, a cDNA microarray was developed from over 60,000 mRNA readings to analyze the expression profiles of transcriptomes of Haematococcus lacustris under astaxanthin-inducing culture conditions, high irradiance and nitrate starvation. Among 20,033 genes on the cDNA microarray, 2,675 genes exhibited a twofold or greater difference in expression. Of these, 1,333 genes were up-regulated and 1,342 genes were down-regulated. A significant decrease in the expression of chlorophyll biosynthesis and light harvesting complex (LHC) related genes were observed under astaxanthin inducing conditions (forming red cyst cells). On the other hand, respirationrelated genes, lipid metabolism-related genes and stress response-related genes were activated in the red cyst cells under stress conditions. These results enabled a better understanding of the cell responses during stress induction of H. lacustris such as photosynthesis, respiration, and some biopathways.