Transcriptomic changes induced by salinity stress in the green microalga Chromochloris zofingiensis

Chromochloris zofingiensis has been considered as potential feedstock for biodiesel production with advantages such as high biomass productivity and great oil content. TAG (triacylglycerol) and astaxanthin accumulate in a well-coordinated manner in response to different stresses in C. zofingiensis. The integrated production of lipids with co-products emerges as a new research direction and is proposed to be a promising approach toward offsetting the algal biodiesel production cost. Therefore, it is suggested C. zofingiensis can serve as research models for the integrated production. Salinity stress simultaneously induced TAG and astaxanthin accumulation in C. zofingiensis. To understand the mechanism underlying TAG and astaxanthin accumulation induced by salinity stress, we applied high-throughput mRNA-sequencing in C. zofingiensis. Chromochloris zofingiensis cells in exponential phase were harvested by centrifugation at 5000 rpm for 5 min and washed twice. Then cells (initial cell density at 0.5 g/L) were re-inoculated in Kuhl medium contained 200 mM of NaCl for salinity stress . Cells were collected for RNA isolation at 0 h and 6 h after re-inoculation. Three biological replicates of algal cultures were carried out under each conditions (salinity stress and control). In total, 6 samples were collected for mRNA-seq.