Temporal transcriptome profiling ofMicrochloropsis gaditanaCCMP526 under hyper-saline conditions

Abstract

37Microalgae can tolerate a wide range of environmental conditions and have been exploited for 38 their lipid and carbohydrate accumulating properties. The utility of this process could be 39 further enhanced through understanding the critical gene regulatory networks that govern the 40 acclimatization process. Advancements in systems biology and sequencing tools now enable 41us to obtain a genome-wide overview of gene expression under particular conditions of 42interest. Under salinity stress, Microchloropsis gaditana CCMP526, a commercially 43 important alga has been previously reported to accumulate carbohydrate and lipid. To 44understand the mechanism of acclimatization, here we report a temporal transcriptomic 45 analysis of M. gaditana under two different salinity levels (55 and 100 PSU). The short term 46 (0, 1 and 6 h) and long term (24 and 72 h) responses of the salt-induced transcript pool were 47used to identify salinity-inducible genes using correspondence analysis. The transcript 48abundance of genes involved in triacylglycerol biosynthesis, membrane lipid modification, 49 carbon assimilation and shunting, and osmolyte biosynthesis indicated that M. gaditana 50 employs a two-stage acclimatization strategy during hypersaline conditions.

Data-Independent-Acquisition-Based Proteomic Approach towards Understanding the Acclimation Strategy of Oleaginous Microalga Microchloropsis gaditana CCMP526 in Hypersaline Conditions

“…In contrast, GO terms for energy-intensive translation (GO:0006412) was enriched at 1 and 6 h after transfer of cells to 100 PSU, suggesting a protein-aided metabolic shift during the later phases (72 h) of acclimation through carbohydrate metabolism (GO:0005975) and homeostatic processes (GO:0042592). The enrichment of the carbohydrate metabolism (GO:0005975) term during the later-phase of growth suggests carbon shunting toward lipid accumulation, which is evident from our physiological 19 and transcriptomic 20 studies on M. gaditana .…”

“…Similarly, we observed salinity-induced dynamics in the transcriptome of M. gaditana. ( 20 ) To understand the fate of cellular metabolism in hypersaline conditions and to establish a relationship between the physiology 19 and transcriptome 20 of salinity-induced M. gaditana , the differentially expressed proteins were analyzed for their biological significance in the following sections. The schematic overview of the key metabolic changes in salinity-stressed M. gaditana is shown in Figure 6 .…”

“… 19 Comparable levels of transcript induction of lipid biosynthetic genes were observed in M. gaditana . 20 …”

“…A systematic investigation using the NGS-based transcriptomic (RNA-Seq) approach was performed to identify the molecular players in salinity tolerance (Karthikaichamy et al, 2020). 20 The results showed active orchestration of carbon flux toward lipid accumulation and osmolyte biosynthesis. Despite the physiological and transcriptomic characterization of salinity response in M. gaditana , the information on the regulation of proteome toward increased salinity levels remained elusive.…”

“…Physiological alterations in the lipid and carbohydrate accumulation have been observed in hypersaline conditions, which prompted us to investigate the genes and proteins involved in the salinity response mechanism. A systematic investigation using the NGS-based transcriptomic (RNA-Seq) approach was performed to identify the molecular players in salinity tolerance (Karthikaichamy et al, 2020) . The results showed active orchestration of carbon flux toward lipid accumulation and osmolyte biosynthesis.…”