Sequenced ascorbate-proline-glutathione seed treatment elevates cadmium tolerance in cucumber transplants

Area of Science:

• Plant Physiology
• Environmental Stress Biology
• Agricultural Science

Background:

• Cadmium (Cd) is a toxic heavy metal that severely impacts plant growth and metabolism.
• Plants possess antioxidant defense systems to mitigate abiotic stresses like cadmium toxicity.
• Ascorbate (AsA), proline (Pro), and glutathione (GSH) are key non-enzymatic antioxidants.

Purpose of the Study:

• To investigate the effects of single and sequential applications of AsA, Pro, and GSH on cucumber (Cucumis sativus) transplants under cadmium stress.
• To evaluate the impact of these treatments on cucumber growth, physio-biochemical attributes, and antioxidant defense system activity.

Main Methods:

• Cucumber seeds were soaked in solutions of AsA, Pro, and GSH, applied individually or in sequence.
• Transplants were subjected to 2 mM Cd stress via irrigation water.
• Measurements included growth parameters, photosynthetic efficiency (SPAD, Fv/Fm, PI), nutrient content (K+, Ca2+), Cd accumulation, and antioxidant enzyme activities.

Main Results:

• Cadmium stress reduced photosynthetic efficiency and nutrient content while increasing Cd accumulation and antioxidant activity.
• Exogenous AsA, Pro, and GSH treatments, applied singly or sequentially, significantly improved growth, photosynthetic efficiency, and nutrient content.
• Treatments also enhanced antioxidant defense system activity and reduced Cd accumulation in roots and leaves, with the sequential AsA-Pro-GSH treatment showing the best results.

Conclusions:

• Ascorbate, proline, and glutathione are effective in mitigating cadmium toxicity in cucumber transplants.
• Sequential application of AsA-Pro-GSH is the most beneficial treatment strategy for enhancing cucumber resilience to cadmium stress.
• GSH treatment alone also shows significant promise for improving cucumber growth under Cd stress.