Effect of elevated temperature on catalase and superoxide dismutase during maize development

Area of Science:

• Plant Physiology
• Biochemistry
• Molecular Biology

Background:

• Antioxidant enzymes like catalase and superoxide dismutase play crucial roles in plant stress tolerance.
• Maize (Zea mays) is a vital crop susceptible to environmental stressors, including heat.

Purpose of the Study:

• To investigate the impact of elevated temperatures on catalase and superoxide dismutase activity in maize seedlings.
• To explore the molecular mechanisms underlying reduced enzyme activity in heat-stressed high-catalase mutant maize lines.

Main Methods:

• Maize seeds (inbred lines W64A, R6-67, D10) were germinated and grown at controlled temperatures (25°C, 35°C, 40°C) for up to 10 days.
• Catalase and superoxide dismutase activities were measured in seedling scutella.
• CAT-2 protein levels and synthesis/degradation rates were assessed in high-catalase mutant lines using a catalase synthesis inhibitor.

Main Results:

• Elevated temperatures (40°C) led to slightly reduced catalase activity in W64A seedlings compared to 25°C.
• Superoxide dismutase activity was lower at 40°C during the initial 3 days of germination but normalized later.
• High-catalase mutant lines (R6-67, D10) showed significantly lower catalase activity at 40°C, correlated with reduced CAT-2 protein levels.
• In R6-67, heat stress increased CAT-2 degradation and decreased its synthesis rate.

Conclusions:

• High temperatures negatively affect key antioxidant enzyme activities in maize seedlings.
• Heat stress impacts catalase levels in high-catalase mutants by altering both protein synthesis and degradation.
• Understanding these responses is crucial for developing heat-tolerant maize varieties.