A Multi-omic Characterization of the Physiological Responses to Salt Stress in Scenedesmus obliquus UTEX393

Abstract Microalgae are one of the most versatile and promising organisms for biomanufacturing. To expedite research and development, we generated an improved genome assembly and annotation of the highly productive microalga Scenedesmus obliquus UTEX393 . We measured the systems level, multi-omic responses during exposure to 15 ppt (high) vs 5 ppt (low/control) salt. Exposure to 15 ppt salt level resulted in a systematic dysregulation of redox balancing components, a reduction in photosynthetic components, and a concomitant increase in lipid accumulation. Using DNA affinity purification sequencing, we identified the regulatory landscape of several transcription factors. Two transcription factors were identified as sharing binding-site homology with Arabidopsis orthologs SPL12 and LHY1 and were experimentally determined to target the promoter regions of genes which encode for enzymes involved in central metabolism. Engineering the redox and metabolic pathways in Scenedesmus obliquus UTEX393 could enhance productivity under higher salt conditions.