Protein that marks day length also coordinates blooming genes

By Rebecca Cheung

Web edition: May 25, 2012

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Day length helps plants determine when to bloom and is sensed by proteins tuned to blue-light wavelengths in the leaves of Arabidopisis thaliana. These proteins, in turn, help switch on genes that trigger flowering in springtime, a new study reveals. A. thaliana tissues where proteins that measure day length reside are shown stained in blue.

Credit: © Science/AAAS

As the days become longer in spring, plants know to bloom thanks to an interaction between several crucial proteins and blue light, scientists report in the May 25 Science. The new work describes the molecular mechanics that enables a light-sensitive protein to help switch on a suite of genes that control flowering. Understanding the biology of how plants regulate flowering could be useful for tweaking crops to start producing food earlier in the year.

“We might be able to grow three times or twice as much in a season,” says study coauthor Takato Imaizumi, a molecular biologist at the University of Washington in Seattle.

Generally, plants need to start blooming around the time when most pollinating insects will be buzzing around — such as in early spring — to maximize their chances of reproducing.Scientists have known that plants have higher levels of the blue-light sensitive protein FKF1 toward the end of the day and that the protein is important for tracking day length. It’s also been shown that another protein, called CO, plays a key role in turning on flowering genes.

In the new work, Imaizumi and his team looked at the flowering plant Arabidopsis thaliana. The researchers show that FKF1 helps stabilize the CO protein long enough to turn on flowering. Blue light — a particular wavelength of visible light that is common in sunlight that shines down at the end of a spring day, around the same time there is more FKF1 — enhances the interaction. FKF1 also lowers levels of a protein that normally serves as a brake on blooming.