Molecular and physiological basis of high photosynthetic efficiency for enhancing crop yield potential

With the growing population in the worldwide, food security is still a global challenge. As the ultimate basis of yield, improving photosynthetic efficiency has been considered as one of the most promising strategies to enhance crop yield. Understanding the physiological and molecular basis of high photosynthesis efficiency is critical to achieve high yield in major crops. By comparing the photosynthetic characterization of high-yield maize varieties from 1970s to 2000s, we revealed that the high photosynthesis is the physiological basis of high yield throughout the variety evolution. Photosynthetic capacity of maize leaves locate at low and middle layers are the key determinates of yield. Moreover, we identified a key transcription factor OsDREB1C by screening the response of low-nitrogen and light status. OsDREB1C conferred substantial yield improvement up to 68.3% in rice, which was driven by enhance photosynthesis and nitrogen use efficiency. Importantly, OsDREB1C shortens the growth duration by promoting early flowering of rice up to 19 days. We further dissected the molecular mechanism that OsDREB1C coordinately regulate photosynthesis, nitrogen utilization and flowering, by activating multiple downstream target genes involved in those pathways. The conserved function of OsDREB1C in wheat and Arabidopsis suggested OsDREB1C can be a powerful tool to boost crop yield with less nitrogen cost.