Overexpression of the soybean transcription factor GmDof4 significantly enhances the lipid content of Chlorella ellipsoidea

Biotechnology for Biofuels

Jianhui Zhang⁵  Qiang Hao⁴  Lili Bai⁵  Jin Xu³  Weibo Yin⁵  Liying Song⁵  Ling Xu⁵  Xuejie Guo⁵  Chengming Fan⁵  Yuhong Chen⁵  Jue Ruan³  Shanting Hao⁵  Yuanguang Li²  Richard R-C Wang¹  Zanmin Hu⁵ 

[1] USDA-ARS, FRRL, Utah State University, 695 N. 1100 E., Logan 84322-6300, UT, USA

[2] State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Meilong Road #130, Shanghai 200237, China

[3] Beijing Institute of Genomics, Chinese Academy of Sciences, Beichen West Road #1, Beijing 100029, China

[4] College of Life Sciences, University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China

[5] Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, China

关键词: Acetyl-coenzyme A carboxylase;    RNA-seq;    Lipid accumulation;    Transcription factor;    Chlorella ellipsoidea;    Microalgae;   

Others  :  1084618
DOI  :  10.1186/s13068-014-0128-4

 received in 2013-10-08, accepted in 2014-08-20,  发布年份 2014

【 摘 要 】

Background

The lipid content of microalgae is regarded as an important indicator for biodiesel. Many attempts have been made to increase the lipid content of microalgae through biochemical and genetic engineering. Significant lipid accumulation in microalgae has been achieved using biochemical engineering, such as nitrogen starvation, but the cell growth was severely limited. However, enrichment of lipid content in microalgae by genetic engineering is anticipated. In this study, GmDof4 from soybean (Glycine max), a transcription factor affecting the lipid content in Arabidopsis, was transferred into Chlorella ellipsoidea. We then investigated the molecular mechanism underlying the enhancement of the lipid content of transformed C. ellipsoidea.

Results

We constructed a plant expression vector, pGmDof4, and transformed GmDof4 into C. ellipsoidea by electroporation. The resulting expression of GmDof4 significantly enhanced the lipid content by 46.4 to 52.9%, but did not affect the growth rate of the host cells under mixotrophic culture conditions. Transcriptome profiles indicated that 1,076 transcripts were differentially regulated: of these, 754 genes were significantly upregulated and 322 genes were significantly downregulated in the transgenic strains under mixotrophic culture conditions. There are 22 significantly regulated genes (|log₂ ratio| >1) involved in lipid and fatty acid metabolism. Quantitative real-time PCR and an enzyme activity assay revealed that GmDof4 significantly up-regulated the gene expression and enzyme activity of acetyl-coenzyme A carboxylase, a key enzyme for fatty acid synthesis, in transgenic C. ellipsoidea cells.

Conclusions

The hetero-expression of a transcription factor GmDof4 gene from soybean can significantly increase the lipid content but not affect the growth rate of C. ellipsoidea under mixotrophic culture conditions. The increase in lipid content could be attributed to the large number of genes with regulated expression. In particular, the acetyl-coenzyme A carboxylase gene expression and enzyme activity were significantly upregulated in the transgenic cells. Our research provides a new way to increase the lipid content of microalgae by introducing a specific transcription factor to microalgae strains that can be used for the biofuel and food industries.

【 授权许可】

   
2014 Zhang et al.; licensee BioMed Central Ltd.

【 图 表 】

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