Modulating plant growth–metabolism coordination for sustainable agriculture

Green revolution varieties of rice and wheat are dwarfed, making them resistant to lodging, and DELLA proteins contribute to this dwarfing. At the same time, green-revolution varieties are not very good at taking up nitrogen, so much of the applied fertilizer is wasted (and polluting). Li et al. have identified and tweaked a control system that enables dwarfed, green-revolution varieties to use nutrients more effectively. A QTL study identified genes that improve nitrogen uptake, one of which encodes the transcription factor GRF4. They found that GRF4 binds to the promoters of several genes involved in N uptake and metabolism, but that its binding is limited by interaction with the DELLA protein SLR1. Alleles of GRF4 that lead to more abundant protein levels lead to enhanced N-use efficiency. They also found that GRF4 regulates genes involved in carbon metabolism (including photosynthesis, sucrose metabolism and sucrose transport) and cell division, also in antagonism with SLR1; as they say, “GRF4–SLR1 antagonism modulates the GA-mediated promotion of cell proliferation, and integrates growth, nitrogen and carbon metabolism regulation.” Green-revolution rice varieties carrying this allele of GRF4 show enhanced grain yields and greater N-use efficiency, without losing the desirable dwarf stature. (Summary by Mary Williams) Nature 10.1038/s41586-018-0415-5