Harnessing natural variation for photosynthetic improvement in next-generation crop breeding

Because agriculture is confronted with escalating climatic and resource challenges, next-generation breeding requires innovative strategies to sustain and enhance crop productivity. As the foundation of carbon fixation in plants, photosynthesis strongly affects crop yield potential. Therefore, improving photosynthetic performance remains a central goal for crop improvement. Plants show substantial natural genetic variation in photosynthetic traits, arising from heritable differences in physiology, including metabolism and regulation, which represent valuable genetic resources for crop breeding. Meanwhile, advances in synthetic biology and photosynthetic genetic engineering provide complementary avenues for enhancing photosynthetic capacity and productivity. In this review, we analyze and synthesize recent progress in research on (i) natural variation in photosynthetic traits across physiological, developmental, and canopy scales; (ii) molecular and genetic regulatory mechanisms underlying photosynthetic diversity and adaptations; (iii) links between photosynthetic efficiency, source-sink coordination, and yield formation; and (iv) emerging strategies for engineering photosynthesis. We also outline remaining challenges and future perspectives. Collectively, these insights provide a strategic framework for leveraging natural genetic diversity and modern biotechnologies to optimize photosynthesis, enhance yield potential, and improve crop resilience under future climate scenarios, further supporting global food security.