EuTGA1, a bZIP transcription factor, positively regulates EuFPS1 expression in Eucommia ulmoides

Area of Science:

• Plant Molecular Biology
• Biochemistry
• Plant Biotechnology

Background:

• Eucommia ulmoides (E. ulmoides) is a key temperate rubber source plant, producing Eucommia ulmoides gum (EUG) with unique properties.
• Farnesyl pyrophosphate synthase (FPS) is the rate-limiting enzyme in EUG biosynthesis, but its transcriptional regulation in E. ulmoides is poorly understood.
• Transcription factors (TFs) play critical roles in regulating plant gene expression, including secondary metabolite biosynthesis.

Purpose of the Study:

• To identify and characterize transcription factors regulating the expression of Farnesyl pyrophosphate synthase 1 (EuFPS1) in E. ulmoides.
• To elucidate the role of identified TFs in the biosynthesis pathway of Eucommia ulmoides gum (EUG).

Main Methods:

• Bioinformatic analysis to identify TGA transcription factors (TFs) in E. ulmoides.
• Promoter analysis to predict binding sites for EuTGAs on the EuFPS1 promoter.
• Yeast one-hybrid and dual-luciferase assays in tobacco to confirm TF-promoter interaction and transcriptional activity.
• Subcellular localization, qRT-PCR, and transient transformation experiments to validate EuTGA1 function.

Main Results:

• Twelve TGA transcription factors were identified in E. ulmoides, with EuTGA1 showing potential interaction with the EuFPS1 promoter.
• EuTGA1 directly binds to the EuFPS1 promoter and significantly enhances its transcriptional activity (over threefold increase) in tobacco.
• EuTGA1 is localized in the nucleus and positively regulates EuFPS1 expression, with its expression pattern mirroring EuFPS1 under varying conditions.
• Low temperature and methyl jasmonate (MeJA) treatments down-regulated EuTGA1 expression, suggesting its role in stress response.

Conclusions:

• EuTGA1 is identified as a positive transcriptional regulator of EuFPS1 in E. ulmoides.
• This study provides crucial insights into the molecular mechanisms controlling EUG biosynthesis by identifying a key regulatory TF.
• The findings lay a theoretical foundation for future research on optimizing EUG production through genetic manipulation of EuTGA1 and EuFPS1.