Biologists at the University of California, San Diego have identified a key protein that links the morning and evening components of the daily biological clock of plants.
Their discovery, detailed in the March 13 issue of Science, solves a longstanding puzzle about the underlying biochemical mechanisms that control plant clocks and could provide a new way to increase the growth and yield of agricultural crops.
The finding is the first outcome of a larger effort to assemble a complete library of all proteins called transcription factors, which regulate genes, in Arabidopsis, a plant often used as a genetic model.
Scientists previously had identified two primary feedback loops in the plant daily clock one that detects the onset of light in the morning and another that tracks when light fades in the evening.
"The best way to construct a robust clock would be to connect the loops so that they both communicate that information to each other," said Steve Kay, dean of the Division of Biological Sciences at UC San Diego whose research team made the discovery. "Now a protein we call CHE has provided that link."
CHE, first predicted nearly a decade ago, has proved difficult to find. Multiple backup systems for many important functions in plants, including timekeeping, frustrate efforts to identify the function of an individual molecule or gene.
"In plants there are a lot of redundancies proteins that do similar things," said Jose Pruneda-Paz, a postdoctoral fellow at UC San Diego and the first author of the study. "In the clock, on top of the redundancies, you have feedback loops that are interconnected. So it's difficult to perturb the system."
Disrupting a protein will fail to reveal its function if the system can compensate for its loss, so the team took a different approach. They sorted through proteins with the ability to bind to DNA, and therefore to regulate genes, and selected candidates
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University of California - San Diego