Exogenous EDDS modifies copper-induced various toxic responses in rice

Area of Science:

• Plant Biology
• Environmental Science
• Biochemistry

Background:

• Copper (Cu) is an essential micronutrient but toxic at high concentrations.
• Ethylenediaminedisuccinic acid (EDDS) is known to enhance phytoextraction of metals, but its mechanism in mitigating copper toxicity is unclear.
• Plant acclimation to heavy metal stress involves complex physiological, genetic, and epigenetic responses.

Purpose of the Study:

• To investigate the effects of excess copper (Cu) on rice seedlings.
• To elucidate the role of EDDS in enhancing plant tolerance to copper toxicity.
• To understand the physiological, genetic, and epigenetic mechanisms underlying copper stress and EDDS mitigation.

Main Methods:

• Rice seedlings were exposed to 200 μM Cu2+ for 3 days, with and without EDDS.
• Physiological parameters measured included growth inhibition, plasma membrane H+-ATPase activity, and electrolyte leakage.
• Gene expression analysis (mRNA levels of OsHMA9, sulfate transporter, metallothionein-like protein) and epigenetic analysis (cell nucleus condensation) were performed.

Main Results:

• Excess Cu (200 μM) inhibited rice seedling growth, decreased H+-ATPase activity, and increased electrolyte leakage, indicating membrane damage.
• Cu stress reduced chlorophyll and carotenoid content and altered the expression of key genes (OsHMA9, sulfate transporter, metallothionein-like protein).
• Cu treatment induced global epigenetic changes, including cell nucleus condensation, which were modulated by EDDS.

Conclusions:

• Maintaining membrane integrity is critical for plant acclimation to copper stress.
• EDDS significantly enhances rice tolerance to excess copper by alleviating Cu-induced physiological, genetic, and epigenetic toxicity.
• EDDS offers a potential strategy to mitigate copper phytotoxicity in agricultural settings.