Trascriptome meta-analysis of microalga Dunaliella tertiolecta under stress condition
Microalgae are photosynthetic organisms, which are considered as a potential source for sustainable metabolite production. Furthermore, stress conditions can affect metabolite production. In this study, a meta-analysis of RNA-seq experiments was performed to evaluate the response of metabolite biosynthesis pathways in Dunaliella tertiolecta to abiotic stress conditions, including high light, nitrogen deficiency, and high salinity. The results indicated down-regulation of light reaction, photorespiration, tetrapyrrole, and lipid-related pathways in salt stress. In comparison to salt stress, nitrogen deficiency mostly induced light reaction and photorespiration metabolisms. The up-regulation of phosphoenolpyruvate carboxylase, phosphoglucose isomerase, bisphosphoglycerate mutase, and glucose-6-phosphate-1-dehydrogenase (involved in central carbon metabolism) was observed under salt, high light, and nitrogen stress conditions. Interestingly, the results indicated that the meta-genes (i.e., modules of genes strongly correlated) tended to be located in a hub of stress-specific PPI (Protein-Protein Interaction) networks. Module enrichment of meta-genes PPI networks highlighted the cross talk between photosynthesis, fatty acids, starch, and sucrose metabolism under multiple stress conditions. Moreover, it was observed that the coordinated expression of the tetrapyrrole intermediated with meta-genes involved in starch biosynthesis. The results of the present study also showed that some pathways such as vitamin B6 metabolism, methane metabolism, ribosome biogenesis, and folate biosynthesis responded to different stress factors specifically. In conclusion, the results of this study revealed the main pathways underlying the abiotic stress responses for optimized metabolite production by the microalga Dunaliella in future studies. PRISMA check list was also included in the study.