Overexpression of the Transcription Factor AtLEC1 Significantly Improved the Lipid Content of Chlorella ellipsoidea

Abstract

Microalgae are considered to be a highly promising source for the production of biodiesel. However, the regulatory mechanism governing lipid biosynthesis has not been fully elucidated to date, and the improvement of lipid accumulation in microalgae is essential for the effective production of biodiesel. In this study, LEAFY COTYLEDON1 (LEC1) from Arabidopsis thaliana, a transcription factor (TF) that affects lipid content, was transferred into Chlorella ellipsoidea. Compared with wild-type (WT) strains, the total fatty acid content and total lipid content of AtLEC1 transgenic strains were significantly increased by 24.20–32.65 and 22.14–29.91%, respectively, under mixotrophic culture conditions and increased by 24.4–28.87 and 21.69–30.45%, respectively, under autotrophic conditions, while the protein content of the transgenic strains was significantly decreased by 18.23–21.44 and 12.28–18.66%, respectively, under mixotrophic and autotrophic conditions. Fortunately, the lipid and protein content variation did not affect the growth rate and biomass of transgenic strains under the two culture conditions. According to the transcriptomic data, the expression of 924 genes was significantly changed in the transgenic strain (LEC1-1). Of the 924 genes, 360 were upregulated, and 564 were downregulated. Based on qRT-PCR results, the expression profiles of key genes in the lipid synthesis pathway, such as ACCase, GPDH, PDAT1, and DGAT1, were significantly changed. By comparing the differentially expressed genes (DEGs) regulated by AtLEC1 in C. ellipsoidea and Arabidopsis, we observed that approximately 59% (95/160) of the genes related to lipid metabolism were upregulated in AtLEC1 transgenic Chlorella. Our research provides a means of increasing lipid content by introducing exogenous TF and presents a possible mechanism of AtLEC1 regulation of lipid accumulation in C. ellipsoidea.

ARTP Mutagenesis of Schizochytrium sp. PKU#Mn4 and Clethodim-Based Mutant Screening for Enhanced Docosahexaenoic Acid Accumulation

“…The expression level of the ACCase gene in Chlorella sorokiniana was found to be upregulated by 2.1-fold from the exponential to stationary phase, indicating that ACCase gene expression is important in lipid biosynthesis [59]. Furthermore, transcriptomics analysis also indicated a closed association between upregulated ACCase and lipid accumulation in Chlorella ellipsoidea [60]. In this study, the two rounds of ARTP mutagenesis coupled with the ACCase inhibitor (clethodim)-based screening yielded the mutant A78.…”

Effects of appropriate low-temperature treatment on the yield and quality of pigmented potato (Solanum tuberosum L.) tubers

“…The chlorophyll content was determined by spectrophotometry [ 48 ]. A total of 0.1 g of each sample was weighed and placed into a 25 mL test tube.…”

Biotechnological Approaches for Biomass and Lipid Production Using Microalgae Chlorella and Its Future Perspectives

“…LEAFY COTYLEDON1 ( LEC1 ) is a central regulator that controls many aspects of seed development, including the maturation phase during which seeds accumulate storage macromolecules and embryos acquire the ability to withstand desiccation in Arabidopsis thaliana [ 135 ]. Overexpression of Arabidopsis LEC1 in C. ellipsoidea enhanced the total fatty acid content (1.33-fold) and total lipid content (1.30-fold) with upregulation of key genes in the lipid synthesis pathway, such as ACCase , GPDH , PDAT1 , and DGAT1 [ 136 ]. In the study of Tokunaga et al ., The candidate DOF transcription factor was endogenously overexpressed in C. vulgaris to improve neutral lipid production, resulting in the production of 1.5-fold higher neutral lipid content compared to control cells in C. vulgaris [ 137 ].…”