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, respiration-related 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.