Exogenous melatonin mitigates boron toxicity in wheat.

Area of Science:

• Plant Physiology
• Agricultural Science
• Biochemistry

Background:

• Boron (B) toxicity is a major abiotic stress limiting crop productivity globally, particularly in arid and semi-arid regions.
• Excessive soil B disrupts crucial physiological and biochemical processes in plants, negatively impacting growth and yield.

Purpose of the Study:

• To investigate the role of melatonin (Mel) in regulating carbohydrate and proline (Pro) metabolism, photosynthesis, and antioxidant systems in wheat seedlings under B toxicity.
• To assess the efficacy of exogenous Mel in alleviating the detrimental effects of high B levels on wheat physiology.

Main Methods:

• Wheat seedlings were subjected to B toxicity conditions with and without foliar application of Mel.
• Measurements included photosynthetic rates, pigment content, enzyme activities (e.g., chlorophyllase, δ-ALAD, CWI), carbohydrate and proline metabolism, oxidative damage markers (malondialdehyde, H2O2), and antioxidant enzyme activities.

Main Results:

• Boron toxicity inhibited photosynthesis, reduced chlorophyll and nutrient content, and induced oxidative damage.
• Melatonin application significantly improved photosynthetic pigment concentration, nutrient content (N, P), carbohydrate and proline metabolism, and plant growth.
• Melatonin enhanced the antioxidant system by increasing the activity of antioxidant enzymes and the content of phenolic compounds, ascorbate, and glutathione, thereby alleviating oxidative stress.

Conclusions:

• Melatonin effectively mitigates B toxicity in wheat by enhancing plant defense mechanisms, including improved nutrient uptake, carbohydrate and proline metabolism, and robust antioxidant activity.
• Exogenous melatonin application represents a promising strategy to improve wheat resilience and productivity in boron-affected soils.