[Mitochondria respiration in developing sunflower seeds].

Area of Science:

• Plant Physiology
• Biochemistry
• Mitochondrial Biology

Background:

• Mitochondria are crucial for energy production in plant seeds.
• Understanding mitochondrial function during seed development is key to optimizing crop yields.
• Sunflower (Helianthus annuus) seed development involves complex metabolic shifts.

Purpose of the Study:

• To investigate the oxidative and phosphorylative activities of sunflower seed mitochondria during embryogenesis.
• To compare these activities across different sunflower cultivars (Polevik, Peredovik, Yubileinyi).
• To determine the temporal dynamics of mitochondrial function from 1 to 54 days post-flowering.

Main Methods:

• Isolation and characterization of mitochondria from developing sunflower seeds.
• Measurement of substrate oxidation rates (succinate, malate, alpha-ketoglutarate).
• Assessment of oxidative phosphorylation efficiency using respiratory control (RC) and ADP/O ratios.

Main Results:

• Succinate oxidation rates were 1.5-2 times higher than malate or alpha-ketoglutarate oxidation.
• Substrate oxidation ratios and maximum oxidation rates varied with seed development and differed among cultivars.
• Oxidation was coupled with phosphorylation throughout development (RC: 1.4–7), but decreased nearing maturation.
• ATP production from Krebs cycle products declined by days 13-15 of embryo growth.

Conclusions:

• Sunflower seed mitochondrial activity is dynamic during development, with cultivar-specific variations.
• A decline in ATP production efficiency occurs during the transition to seed maturation.
• These findings provide insights into the bioenergetics of sunflower seed development.