Cyanobacterial CO₂-concentrating mechanism components: Function and prospects for plant metabolic engineering

Global population growth is projected to outpace plant-breeding improvements in major crop yields within decades. To ensure future food security, multiple creative efforts seek to overcome limitations to crop yield. Perhaps the greatest limitation to increased crop yield is photosynthetic inefficiency, particularly in C₃ crop plants. Recently, great strides have been made toward crop improvement by researchers seeking to introduce the cyanobacterial CO₂-concentrating mechanism (CCM) into plant chloroplasts. This strategy recognises the C₃ chloroplast as lacking a CCM, and being a primordial cyanobacterium at its essence. Hence the collection of solute transporters, enzymes, and physical structures that make cyanobacterial CO₂-fixation so efficient are viewed as a natural source of genetic material for C₃ chloroplast improvement. Also we highlight recent outstanding research aimed toward the goal of introducing a cyanobacterial CCM into C₃ chloroplasts and consider future research directions.