Key Protein Helps Plants Know When To Flower

An 80-year old mystery has just had some new light shed on it. A recent study shows that the complex, automated process is a result of molecular-level events, a plant's circadian rhythm, and sunlight. 

The plants produce a protein known as FLOWERING LOCUS T at specific times of the year. The protein is first produced in the leaves, and then travels to do the plant's shoot apex, which is where the plant's cells are undifferentiated. 

The plant studied was the simple  Arabidopsis, a flowering plant related to cabbage and mustard.

"If we can regulate the timing of flowering, we might be able to increase crop yield by accelerating or delaying this. Knowing the mechanism gives us the tools to manipulate this," said Takato Imaizumi, a University of Washington assistant professor of biology and co-author of the paper. 

The scientists hope to apply these findings to more complex plants, such as rice, or wheat, or barley. This in turn might allow farmers to increase their crop yields and produce healthier plants.

The paper focused on the FKF1 protein, which is a photoreceptor. The protein which is activated by sunlight, plays a key role in the plant determining when to flower.

"The FKF1 photoreceptor protein we've been working on is expressed in the late afternoon every day, and is very tightly regulated by the plant's circadian clock," Imaizumi said. "When this protein is expressed during days that are short, this protein cannot be activated, as there is no daylight in the late afternoon. When this protein is expressed during a longer day, this photoreceptor makes use of the light and activates the flowering mechanisms involving FLOWERING LOCUS T. The circadian clock regulates the timing of the specific photoreceptor for flowering. That is how plants sense differences in day length."

The protein allows the plant to know when would be the most ideal environment in which to flower. When the days are short, for instance during winter, the flower will not have as much sunlight as when the days are longer, in the summer. The plant is basically assessing the odds of its offspring's survival.