Progress and prospects of C 4 trait engineering in plants.

Incorporating C 4 photosynthetic traits into C 3 crops is a rational approach for sustaining future demands for crop productivity. Using classical plant breeding, engineering this complex trait is unlikely to achieve its target. Therefore, it is critical and timely to implement novel biotechnological crop improvement strategies to accomplish this goal. However, a fundamental understanding of C 3 , C 4 , and C 3 -C 4 intermediate metabolism is crucial for the targeted use of biotechnological tools. This review assesses recent progress towards engineering C 4 photosynthetic traits in C 3 crops. We also discuss lessons learned from successes and failures of recent genetic engineering attempts in C 3 crops, highlighting the pros and cons of using rice as a model plant for short-, medium- and long-term goals of genetic engineering. This review provides an integrated approach towards engineering improved photosynthetic efficiency in C 3 crops for sustaining food, fibre and fuel production around the globe.