Enhancing global food security by increasing the productivity of green revolution varieties of cereals risks increasing the collateral environmental damage produced by inorganic nitrogen fertilizers. Improvements in the efficiency of nitrogen use of crops are therefore essential; however, they require an in-depth understanding of the co-regulatory mechanisms that integrate growth, nitrogen assimilation and carbon fixation. Here we show that the balanced opposing activities and physical interactions of the rice GROWTH-REGULATING FACTOR 4 (GRF4) transcription factor and the growth inhibitor DELLA confer homeostatic co-regulation of growth and the metabolism of carbon and nitrogen. GRF4 promotes and integrates nitrogen assimilation, carbon fixation and growth, whereas DELLA inhibits these processes. As a consequence, the accumulation of DELLA that is characteristic of green revolution varieties confers not only yield-enhancing dwarfism, but also reduces the efficiency of nitrogen use. However, the nitrogen-use efficiency of green revolution varieties and grain yield are increased by tipping the GRF4-DELLA balance towards increased GRF4 abundance. Modulation of plant growth and metabolic co-regulation thus enables novel breeding strategies for future sustainable food security and a new green revolution.

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Nonaqueous redox fl ow batteries are emerging fl ow-based energy storage technologies that have the potential for higher energy densities than their aqueous counterparts because of their wider voltage windows. However, their performance has lagged far behind their inherent capability due to one major limitation of low solubility of the redox species. Here, a molecular structure engineering strategy towards high performance nonaqueous electrolyte is reported with signifi cantly increased solubility. Its performance outweighs that of the state-of-the-art nonaqueous redox fl ow batteries. In particular, an ionic-derivatized ferrocene compound is designed and synthesized that has more than 20 times increased solubility in the supporting electrolyte. The solvation chemistry of the modifi ed ferrocene compound. Electrochemical cycling testing in a hybrid lithium-organic redox fl ow battery using the assynthesized ionic-derivatized ferrocene as the catholyte active material demonstrates that the incorporation of the ionic-charged pendant signifi cantly improves the system energy density. When coupled with a lithium-graphite hybrid anode, the hybrid fl ow battery exhibits a cell voltage of 3.49 V, energy density about 50 Wh L −1 , and energy effi ciency over 75%. These results reveal a generic design route towards high performance nonaqueous electrolyte by rational functionalization of the organic redox species with selective ligand.