By Lisa Lock and Robert Egan
Researchers from the University of Oxford, Nanjing Agricultural University, and Institute of Genetics and Developmental Biology (Chinese Academy of Sciences) have finally identified the master regulator in plants that balances root and shoot growth when nutrients are limited. In field trials, rice plants with an improved version of the gene had yield increases of up to 24%. The breakthrough, published today (26 February) in the journal Science, could ultimately improve global crop yields while reducing dependence on synthetic fertilizers.
Nitrogen fertilizer is essential for modern agriculture but is environmentally costly, contributing to greenhouse gas emissions, water pollution, and soil degradation. Crops typically respond to nitrogen deficiency by investing more in root growth to forage for nutrients, often at the expense of shoot development and grain production. While adaptive in the wild, this trade-off limits agricultural productivity.
Up to now, the molecular driver of this developmental switch has been unknown. In the new study, the researchers not only identified the gene responsible, but demonstrated that manipulating this in rice can maintain shoot growth and yields even when nitrogen levels are low.
In controlled greenhouse and field experiments, the researchers showed that rice plants lacking a functional version of a gene called WRINKLED1a lost the ability to invest more in root growth under low-nitrogen conditions, and had reduced shoot growth when nitrogen was abundant. Conversely, plants genetically modified to overexpress the gene showed stronger growth in both roots and shoots, as well as a more constant root-to-shoot ratio as external nitrogen levels varied.
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