Plant Defense Against Heavy Metals

Plants employ various strategies to cope with heavy metal toxicity. One crucial biochemical defense mechanism involves the synthesis of specific molecules that bind to and sequester these toxic metals, rendering them less harmful.

Role of Phytochelatin

Phytochelatin (PC) is a key molecule synthesized by plants in response to heavy metal stress. It's a peptide that effectively chelates (binds) heavy metal ions like cadmium (Cd), mercury (Hg), lead (Pb), and copper (Cu).

• Synthesis: PCs are enzymatically synthesized from glutathione (GSH).
• Function: The synthesized PCs bind to heavy metals, forming stable metal-PC complexes.
• Detoxification: These complexes are often sequestered into cellular compartments like vacuoles, preventing interference with essential cellular processes. This effectively detoxifies the heavy metals.

Analysis of Other Options

• Calmodulin: This is a calcium-binding protein involved in intracellular calcium signaling pathways. It does not directly bind heavy metals for detoxification.
• Tubulin: This protein is the subunit forming microtubules, which are essential components of the cytoskeleton. It is not involved in heavy metal detoxification.
• Systemin: This is a plant hormone precursor involved in wound signaling and defense responses against herbivores. It does not play a role in heavy metal detoxification.

Therefore, the synthesis of Phytochelatin is a primary defense mechanism adopted by plants for the detoxification of heavy metals.