Engineering photosynthesis: progress and perspectives

Abstract

Photosynthesis is the basis of primary productivity on the planet. Crop breeding has sustained steady improvements in yield to keep pace with population growth increases. Yet these advances have not resulted from improving the photosynthetic process per se but rather of altering the way carbon is partitioned within the plant. Mounting evidence suggests that the rate at which crop yields can be boosted by traditional plant breeding approaches is wavering, and they may reach a "yield ceiling" in the foreseeable future. Further increases in yield will likely depend on the targeted manipulation of plant metabolism. Improving photosynthesis poses one such route, with simulations indicating it could have a significant transformative influence on enhancing crop productivity. Here, we summarize recent advances of alternative approaches for the manipulation and enhancement of photosynthesis and their possible application for crop improvement.

Keywords: CCM; Calvin-Benson cycle; Rubisco; crop improvement; light-use efficiency; photosynthesis.

Figure 1.. A number of routes are being studied to improve photosynthesis in crop plants.

These include (1) improving the efficiency of the primary CO ₂-fixing enzyme Rubisco, (2) optimizing elements of the Calvin-Benson cycle, (3) introducing the carboxysome-based carbon concentrating mechanism (CCM) from cyanobacteria, (4) introducing an algal pyrenoid CCM, and (5) improving the photochemical response of photosynthesis to rapid changes in light conditions. Further studies are also related to attempts to convert C ₃ crops such as rice to the more efficient C ₄-type photosynthesis.