Transcriptomics highlights dose-dependent response of poplar to a phenanthrene contamination

Area of Science:

• Environmental Science
• Molecular Biology
• Plant Science

Background:

• Polycyclic aromatic hydrocarbon (PAH) contamination in industrial soils presents environmental challenges.
• Phytoremediation using trees is a cost-effective bioremediation strategy, but tree defense mechanisms against PAHs are not well understood.
• Identifying molecular markers for PAH toxicity is crucial for assessing plant stress.

Purpose of the Study:

• To investigate the molecular response of Populus canadensis to phenanthrene (PHE) contamination.
• To identify dose-dependent transcriptomic changes and adaptive defense mechanisms in poplar roots and leaves.
• To explore the potential of molecular markers for detecting PAH toxicity.

Main Methods:

• RNA-sequencing (RNA-seq) analysis of poplar roots and leaves exposed to a PHE gradient (100-2000 mg kg⁻¹).
• Application of DRomics tool to identify dose-response relationships and differentially expressed genes (DEGs).
• Analysis of gene expression related to ethylene signaling, oxidative stress, and biotic stress responses.

Main Results:

• Significant transcriptomic changes were observed, with approximately 50% of deregulated genes responding below 400 mg PHE kg⁻¹.
• Highest numbers of DEGs were detected at low (200-700 mg kg⁻¹) and high (1500-2000 mg kg⁻¹) PHE concentrations in both roots and leaves.
• Activation of ethylene signaling, oxidative stress responses (ROS scavenging, phenylpropanoid biosynthesis), and disruption of biotic stress pathways were observed in a dose-dependent manner.

Conclusions:

• Populus canadensis exhibits complex, dose-dependent adaptive defense mechanisms against PHE toxicity.
• Transcriptomic shifts reveal poplar's ability to cope with PAH contamination, supporting its role in phytoremediation.
• The study provides insights into molecular markers for assessing plant stress under PAH exposure.