Tuning the C₄ supercharger: improving photosynthesis and yield in C₄ crops

Area of Science:

• Plant Science
• Biochemistry
• Crop Physiology

Background:

• C4 crops (e.g., maize, sorghum) are crucial for global food and bioenergy due to efficient CO2 concentrating mechanisms.
• Despite advantages, C4 photosynthesis has potential for optimization to increase yield and carbon sequestration.
• Current models suggest limitations in C4 photosynthetic flux can be addressed.

Purpose of the Study:

• To review metabolic and physiological limitations in C4 photosynthesis.
• To highlight genetic strategies for optimizing C4 flux using model systems like Setaria viridis.
• To explore novel approaches for enhancing C4 crop performance and resilience.

Main Methods:

• Analysis of steady-state and dynamic models predicting C4 photosynthetic limitations.
• Review of experimental progress in testing genetic strategies in model crops.
• Exploration of under-researched areas like light-harvesting and ATP generation in bundle sheath cells.

Main Results:

• Key limitations identified include carboxylase activity, electron transport, and mesophyll/bundle sheath conductance.
• Genetic strategies are being tested in model crops to alleviate these limitations.
• Enhancing light-harvesting, ATP generation, metabolite exchange, and decarboxylation pathways are promising avenues.

Conclusions:

• Improving C4 photosynthesis requires coordinated manipulation of multiple biochemical and regulatory processes.
• Enhanced understanding will boost C4 crop productivity and resilience.
• Engineering C4 traits into C3 crops is a long-term goal for food security and climate adaptation.