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Background <p>Microalgal biodiesel is a key fossil fuel alternative, but enhancing lipid accumulation via single metabolic gene overexpression is often ineffective. Transcription factor engineering overcomes this by coordinating multiple metabolic pathways. To address the unexplored role of <i>LEC1</i>-type transcription factors in diatoms, we engineered the euryhaline and psychrotolerant biodiesel candidate diatom <i>Phaeodactylum tricornutum</i> through heterologous expression of the key plant lipid regulators <i>AtLEC1</i> and <i>AtL1L</i>.</p> Results <p>Codon-optimized genes driven by the endogenous <i>fcpA</i> promoter were integrated into the nuclear genome, with regulators localization confirmed in the nucleus. Crucially, <i>AtL1L</i> transformants exhibited significant redirection of carbon flux from carbohydrates toward lipids, evidenced by lipid content increasing to 29.8%-33.9% of dry weight compared to 20.9% in wild-type controls while carbohydrates decreased to 13.3%-16.5% from 23.1%. <i>AtL1L</i> transformants accumulated 42–64% more neutral lipids and 48–68% higher total fatty acids without compromising biomass yield or photosynthetic efficiency (Fv/Fm). Molecular analyses revealed coordinated upregulation of key lipogenic, glycolytic and pyruvate metabolism genes such as acetyl-CoA carboxylase, pyruvate kinase and malic enzyme, which were corroborated by significant increases in corresponding enzyme activities and NADPH levels. Metabolite profiling confirmed accumulation of lipid precursors including acetyl-CoA (1.7-fold elevation) concurrent with reduction of sugars like glucose to less than 39% of wild-type levels.</p> Conclusions <p>This study demonstrates the first functional transfer of plant transcription factors to diatoms, providing a transformative strategy for high-productivity microalgal biodiesel.</p> Graphical abstract <p></p>

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Heterologous expression of AtLEC1 and AtLEC1-LIKE transcription factors redirects carbon flux toward lipid accumulation in diatom

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年12月11日

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  • Yuxian Chen,
  • Lijing Geng,
  • Zina Hao,
  • Nan Ding,
  • Jiani Di,
  • Hesheng Hou,
  • Lili Zhang,
  • Hui Wang

摘要

Background

Microalgal biodiesel is a key fossil fuel alternative, but enhancing lipid accumulation via single metabolic gene overexpression is often ineffective. Transcription factor engineering overcomes this by coordinating multiple metabolic pathways. To address the unexplored role of LEC1-type transcription factors in diatoms, we engineered the euryhaline and psychrotolerant biodiesel candidate diatom Phaeodactylum tricornutum through heterologous expression of the key plant lipid regulators AtLEC1 and AtL1L.

Results

Codon-optimized genes driven by the endogenous fcpA promoter were integrated into the nuclear genome, with regulators localization confirmed in the nucleus. Crucially, AtL1L transformants exhibited significant redirection of carbon flux from carbohydrates toward lipids, evidenced by lipid content increasing to 29.8%-33.9% of dry weight compared to 20.9% in wild-type controls while carbohydrates decreased to 13.3%-16.5% from 23.1%. AtL1L transformants accumulated 42–64% more neutral lipids and 48–68% higher total fatty acids without compromising biomass yield or photosynthetic efficiency (Fv/Fm). Molecular analyses revealed coordinated upregulation of key lipogenic, glycolytic and pyruvate metabolism genes such as acetyl-CoA carboxylase, pyruvate kinase and malic enzyme, which were corroborated by significant increases in corresponding enzyme activities and NADPH levels. Metabolite profiling confirmed accumulation of lipid precursors including acetyl-CoA (1.7-fold elevation) concurrent with reduction of sugars like glucose to less than 39% of wild-type levels.

Conclusions

This study demonstrates the first functional transfer of plant transcription factors to diatoms, providing a transformative strategy for high-productivity microalgal biodiesel.

Graphical abstract