Phenanthrene-triggered tricarboxylic acid cycle response in wheat leaf

Area of Science:

• Biochemistry
• Plant Physiology
• Environmental Science

Background:

• The tricarboxylic acid (TCA) cycle is crucial for energy metabolism in plants.
• Plant responses to polycyclic aromatic hydrocarbons (PAHs) pollution, particularly concerning TCA cycle function, remain largely uncharacterized.

Purpose of the Study:

• To investigate the impact of phenanthrene, a representative PAH, on TCA cycle intermediates and enzyme activity in wheat.
• To elucidate the molecular mechanisms underlying TCA cycle alterations in plants exposed to PAH pollution.

Main Methods:

• High-performance liquid chromatography (HPLC) was used to quantify TCA cycle intermediates.
• Isobaric tags for relative and absolute quantitation (iTRAQ) proteomics analyzed protein expression changes.
• Real-time PCR confirmed gene expression patterns of key TCA cycle enzymes.

Main Results:

• Phenanthrene exposure altered TCA cycle intermediate concentrations, notably increasing citrate and malate while decreasing others like α-ketoglutarate and pyruvate.
• Proteomic analysis revealed upregulation of pyruvate dehydrogenase, dihydrolipoyllysine-residue succinyltransferase, and fumarate hydratase.
• Gene expression analysis showed differential regulation of TCA cycle enzymes, with some promoted and others suppressed under phenanthrene stress.

Conclusions:

• Pyruvate reduction is identified as a key factor in TCA cycle inactivation under phenanthrene exposure.
• Increased malate concentration and activation of specific conversion enzymes suggest complex metabolic adjustments.
• This study provides novel insights into plant energy metabolism adaptation to PAH contamination.