A MITE-mediated Cis-regulatory module regulates PsiGCN2 expression for high-intensity light acclimation in Populus
Chenhao Bu1,2, Yuepeng Song1,2, Yuhan Gao1,2
1National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, No. 35, Qinghua East Road, Beijing 100083, P. R. China.
Plant Physiology
|June 2, 2026
Summary
A miniature inverted-repeat transposable element (MITE) near PsiGCN2 enhances photoprotection in poplar trees by regulating gene expression. This discovery reveals a new mechanism for light acclimation in plants under high-light stress.
Area of Science:
- Plant molecular biology
- Genetics
- Photosynthesis research
Background:
- Understanding long-term photoprotection in perennial trees under high light is crucial but poorly understood.
- The role of transposable elements in regulating plant stress responses, particularly light acclimation, needs further investigation.
Purpose of the Study:
- To investigate the genetic basis of photoprotection in perennial trees under sustained high-light exposure.
- To identify key genes and regulatory elements involved in light acclimation mechanisms.
- To elucidate the role of miniature inverted-repeat transposable elements (MITEs) in modulating photoprotection.
Main Methods:
- Utilized transient heterologous reporter assays to assess promoter activity of PsiGCN2.
- Conducted a genome-wide association study (GWAS) on 334 accessions to link genetic variations with photoprotective traits.
- Generated loss-of-function paggcn2 mutants to evaluate photoprotection under high-light stress.
- Performed transcriptomic profiling to identify differentially expressed genes in mutants.
- Analyzed protein-protein interactions and performed phylogenetic analysis of MITEs.
Main Results:
- A MITE upstream of PsiGCN2 was found to reduce promoter activity, suggesting a cis-regulatory role.
- PsiGCN2 was significantly associated with electron transport rate (ETR) and non-photochemical quenching (NPQ) under high light.
- paggcn2 mutants exhibited enhanced photoprotection, with higher PSII efficiency, increased NPQ, and sustained ETR.
- Transcriptomic analysis revealed upregulation of photosynthetic antenna proteins and reduced mitogen-activated protein kinase signaling in mutants.
- PsiGCN2 acts as a regulatory hub coordinating proteostasis, photosynthesis, and RNA metabolism.
- MITEs are widespread, with insertions near transcriptional boundaries, and show evidence of ancient amplification coinciding with climate shifts.
Conclusions:
- A MITE-PsiGCN2 regulatory axis significantly influences the balance between photoprotection and photosynthetic efficiency in trees.
- Promoter-proximal MITE insertions contribute to transcriptional modulation of light acclimation in woody species.
- This study provides novel insights into the genetic mechanisms underlying plant adaptation to high-light stress.
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