When crops have high sugar levels, they produce energy-dense oil stored in the seeds. However, oil production slows when sugar levels are low. Whether or not to produce oil is essentially a set of biochemical reactions. High sugar levels lead to one outcome; low levels lead to another. Now, scientists have discovered new details about how a sugar-signaling molecule helps regulate oil production in plant cells. This signaling molecule interferes with a biochemical chain of events that puts the brakes on oil production when sugar is low.
Scientists identified key details and a vital intermediate protein in the oil-producing cascade. A detailed understanding of the biochemical interactions that affect oil production could point to new ways to develop plants that could produce substantial amounts of oil of economic value, for instance for use as biofuels or other oil-based products. The oils could also be used to produce other oil-based products. This study points to at least one specific plant protein the scientists can alter in an attempt to modify cells' regulatory circuitry to prioritize oil production.
This study builds on the team's previous research, which established clear links between a protein complex that senses sugar levels in plant cells (specifically a subunit called KIN10) and another protein that serves as the "on switch" for oil production (WRINKLED1). Using this knowledge, the team demonstrated that they could use combinations of genetic variants that increase sugar accumulation in plant leaves to drive up oil production. The new work provides a more detailed understanding of the link between sugar signaling and oil production, identifying precisely which molecules regulate the balance and how. Specifically, they found that a molecule known as trehalose 6-phosphate—the levels of which rise and fall with those of sugar—binds with KIN10 and interferes with its interaction with a previously unidentified intermediate in this process (known as GRIK1) to block KIN10's ability to shut off oil biosynthesis. The findings suggest that changing the amino acid sequence of KIN10 in a way that mimics the effects of its interaction with the sugar-signaling molecule trehalose 6-phosphate could be one way to make plants produce more oil.
Brookhaven National Laboratory
The Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences and the Max Planck Society (Z.Z.) funded this research.
Z. Zhai, J. Keereetaweep, H. Liu, R. Feil, J.E. Lunn, and J. Shanklin, "Trehalose 6-phosphate positively regulates fatty acid synthesis by stabilizing WRINKLED1." The Plant Cell (2018). [DOI: 10.1105/tpc.18.00521]
Brookhaven National Laboratory press release: How a Molecular Signal Helps Plant Cells Decide When to Make Oil
Brookhaven National Laboratory press release: Study IDs Link Between Sugar Signaling and Regulation of Oil Production in Plants
Brookhaven National Laboratory press release: With Extra Sugar, Leaves Get Fat Too
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