Zinc tolerance modulation in Myracrodruon urundeuva plants

Area of Science:

• Plant Physiology
• Environmental Toxicology
• Biochemistry

Background:

• Zinc (Zn) is an essential micronutrient but can be toxic at elevated concentrations.
• Understanding plant tolerance mechanisms is crucial for phytoremediation and agriculture.
• Myracrodruon urundeuva is a species with potential for Zn phytostabilization.

Purpose of the Study:

• To investigate zinc tolerance and the underlying mechanisms in Myracrodruon urundeuva seedlings.
• To evaluate the impact of increasing zinc doses on plant growth and antioxidant systems.

Main Methods:

• Seedlings were exposed to varying zinc (Zn) doses (0-200 mg Zn kg⁻¹) for 120 days.
• Growth parameters (biomass, pigments, photosynthesis) were assessed.
• Antioxidant system components (redox potential, enzyme activities like SOD, CAT, APX, GR, GPX) were analyzed.

Main Results:

• Myracrodruon urundeuva demonstrated significant zinc tolerance.
• Zinc doses above 80 mg Zn kg⁻¹ induced phytotoxicity via oxidative stress (H₂O₂ accumulation, lipid peroxidation).
• Antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) activities increased with Zn presence; ascorbate peroxidase (APX) and glutathione reductase (GR) were stimulated at lower Zn doses but inhibited at higher ones.

Conclusions:

• Zn tolerance in M. urundeuva is associated with modulated leaf antioxidant systems.
• Ascorbate peroxidase (APX) plays a key role in scavenging hydrogen peroxide (H₂O₂).
• The redox status of leaves is linked to the regulation of APX and GR activities under Zn stress.