Eugenol-inhibited root growth in Avena fatua involves ROS-mediated oxidative damage

Area of Science:

• Plant Science
• Biochemistry
• Environmental Science

Background:

• Plant essential oils and monoterpenes are known growth retardants.
• The phytotoxicity mechanism of natural herbicides like eugenol requires elucidation.

Purpose of the Study:

• To investigate the phytotoxic mechanism of eugenol on Avena fatua root growth.
• To explore the physiological and biochemical alterations induced by eugenol.

Main Methods:

• Assessed eugenol's effect on Avena fatua germination and root/coleoptile growth.
• Quantified reactive oxygen species (ROS) generation (H2O2, superoxide, hydroxyl radical).
• Measured membrane integrity via malondialdehyde, conjugated dienes, and electrolyte leakage.
• Determined antioxidant enzyme activities (SOD, CAT, APX, GPX, GR).

Main Results:

• Eugenol (100-1000 µM) inhibited root growth more than coleoptile growth.
• Increased ROS generation and membrane damage (lipid peroxidation, electrolyte leakage) were observed.
• Significant upregulation of ROS-scavenging antioxidant enzymes occurred in response to eugenol.

Conclusions:

• Eugenol inhibits early root growth primarily through ROS-mediated oxidative stress and membrane damage.
• The plant's antioxidant defense system is activated but insufficient to fully counteract eugenol's phytotoxicity.