Primary metabolism is associated with the astaxanthin biosynthesis in the green algae Haematococcus pluvialis under light stress

Haematococcus pluvialis is a kind of native bioresource, which accumulate high abundance of astaxanthin, one of the most important bioactive compounds, under various biotic and abiotic stress conditions particularly under high light. However, the global metabolic responses to high light in general and the relationship between primary metabolism and astaxanthin accumulation in particular are still obscure. In this study, non-targeted metabolomics approach was first to be used to profile the dynamic metabolic changes of H. pluvialis along astaxanthin accumulation under different light intensities, in which > 200 low molecular metabolites were identified. The integration of metabolomics data with previous transcriptomic data uncovered several metabolic pathways including raffinose family oligosaccharides biosynthesis pathway, GSH metabolism pathways, pyrimidine and purine metabolism pathways, TCA cycle, and phospholipids, that are important for astaxanthin biosynthesis under high light intensity, pinpointing a metabolic shift from primary metabolism to astaxanthin biosynthesis. Exogenous application of related metabolites such as nucleotides, carbohydrates and amino acids in algal medium confirmed the metabolic link between primary metabolism and astaxanthin biosynthesis. Our results provides with a solid metabolic base for the manipulation of astaxanthin production under high light stress, and reveals metabolic insights into the adaption strategy of H. pluvialis against light stress conditions.