Toward Cool C4 Crops

C4 photosynthesis under optimal conditions enables higher-efficiency use of light, water, and nitrogen than the C3 form used by many crops. It is associated with the most productive terrestrial plants and crops but is largely limited to the tropics and subtropics. It has been argued that the C4 photosynthetic apparatus is inherently limited to warm environments. A small group of C4 species appear to have overcome this, and in contrast to the major C4 crop, maize, these species are able to acclimate their photosynthetic apparatus to chilling conditions. This review explores the mechanisms underlying this difference as well as the potential of introducing these changes into maize and other warm-climate C4 crops.