When plants’ sugar levels are low, they reduce their investment in energy-intensive fatty acid synthesis. But in biofuel production, people might want to coax plants into making more fatty acid or oil. Now, researchers from Brookhaven National Laboratory (BNL) and Max Planck Institute of Molecular Plant Physiology report a molecule that regulates plants’ oil synthesis “on” switch (Plant Cell 2018, DOI: 10.1105/tpc.18.00521). When plants in nature sense their sugar level is low, they degrade their oil production “on” switch—a transcription factor called WRINKLED1. When sugar levels are high, WRINKLED1 is stable, making it possible to crank up oil production. Using biochemical analyses and mutant plants, the team led by John Shanklin of BNL found that a small molecule called trehalose 6-phosphate (T6P) is a signal balancing sugar levels and oil production. When sugar levels are high, T6P levels are high, and T6P prevents a sugar sensor protein from tagging WRINKLED1 for degradation. Shanklin says understanding more about this mechanism can allow researchers to decouple plants’ oil production from their sugar level, eventually engineering biofuel plants that make more oil without sacrificing any sugar production or growth.