"The roots" of selenium toxicity: A new concept

Area of Science:

• Plant Biology
• Environmental Toxicology
• Biochemistry

Background:

• Elevated selenium (Se) levels induce toxicity in non-accumulator plants.
• Previously, selenoprotein accumulation and oxidative stress were primary suspected causes.
• Recent research suggests a more complex interplay of stress factors.

Purpose of the Study:

• To investigate the role of reactive nitrogen species (RNS) and phytohormones in selenium toxicity.
• To present RNS and phytohormones as novel contributors to plant Se toxicity.
• To expand understanding beyond traditional oxidative stress mechanisms.

Main Methods:

• Review of recent literature and previous findings.
• Analysis of data on plant responses to selenium exposure.
• Focus on molecular and physiological stress indicators.

Main Results:

• Selenium exposure disrupts the homeostasis of reactive oxygen and nitrogen species, leading to nitro-oxidative stress.
• Inhibited root elongation, a key symptom of Se toxicity, is partly mediated by hormonal disturbances.
• Cytokinin signaling in roots is implicated in sensing selenium stress.

Conclusions:

• Nitro-oxidative stress, resulting from disrupted RNS and ROS balance, significantly contributes to plant selenium toxicity.
• Phytohormones, particularly cytokinin, play a crucial role in plant responses to selenium stress.
• RNS and phytohormones are identified as new, critical players in understanding plant selenium toxicity.