Comparative transcriptomics reveals molecular components associated with differential lipid accumulation between microalgal sp., Scenedesmus dimorphus and Scenedesmus quadricauda

Scenedesmus is considered as a potential oil-producing green microalgae having higher lipid content with suitable fatty acid profile (high oleic acid) for biodiesel production. Comparative transcriptome analysis of two Scenedesmus sp., viz. Scenedesmus dimorphus (26%) and Scenedesmus quadricauda (14%) having equivalent biomass and variable lipid content was performed to uncover molecular mechanisms controlling differential lipid production. 76,969 and 40,979 CDSs were predicted from the transcriptomes of S. dimorphus and S. quadricauda respectively, which were subsequently mapped to metabolic pathways. Overall up-regulation of metabolic pathways contributing precursors to storage lipid biosynthesis was observed in S. dimorphus. Glyceraldehyde 3-phosphate dehydrogenase, enolase, acetyl-CoA synthetase, pyruvate dehydrogenase, ATP citrate lyase, glycerol kinase, citrate synthase were identified as major regulators of high lipid content in S. dimorphus. Further, WRINKLED1 transcription factor significantly correlated with high lipid accumulation as revealed by reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) in three growth stages of two species. This study provides a broad view of storage lipid production in Scenedesmus species with potential implications in designing suitable genetic interventions towards increase in lipid content vis-à-vis central carbon metabolism.