Ion exclusion
nounPronunciation: /ˌaɪɑːn ɪkˈskluːʒən/
The selective prevention of the uptake or translocation of toxic ions (particularly Na⁺ and Cl⁻) into plant tissues, maintaining ionic homeostasis under saline stress conditions. This mechanism operates at the root plasma membrane and vascular tissues to compartmentalize ions away from sensitive cellular sites.
Plain English
Plants actively block or minimize harmful salt ions from entering and traveling to sensitive tissues during salt stress.
Etymology & History
Usage
"Ion exclusion at the root endodermis was the primary mechanism conferring salt tolerance in the rice cultivar IR29."
Style guide notes: Distinguish between ion exclusion (prevention of entry) and ion compartmentalization (storage in vacuoles) in mechanistic discussions.
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Related Terms
Frequently Asked Questions
Where does ion exclusion primarily occur in plant roots?
It occurs mainly at the root endodermis and Casparian strip, which regulate solute entry into the vascular system.
How do plants exclude ions at the cellular level?
Through selective transporter proteins on cell membranes that restrict Na⁺ and Cl⁻ uptake while allowing essential nutrient uptake.
Why Test Candidates on This?
Ion exclusion mechanisms are essential for understanding salt tolerance variation and identifying breeding targets for saline-adapted crops.
Required skill level: Senior