How do Plants Know When to Flower?

A flowering plant is determined by the season. There are plants that bloom in spring, fall, or summer. 

Now, scientists believe they have found the answer to the riddle unanswered for 80 years, which is how plants know when they have to evolve. Knowledge of the particulars right time to flowering plants can be very important in order to reproduce successfully. It involves the sun's rays, a series of molecular processes, and the plant circadian clock. 

Understanding how flowering
works in Arabidopsis should
lead to a better understanding
of how the same genes work
in crop plants such as rice. 
(Picture from: http://www.eurekalert.org/)

With a simple understanding of flowering in plants, such as Arabidopsis, researchers can also learn how genes work in a complex food crops, eg rice, wheat, and barley. 

Takato Imaizumi, biology professor of University of Washington, says this research could be a tool to manipulate the flowering time. "We probably can increase yields by accelerating or delaying the time," Imaizumi said. 

At certain times of the year, the plant produces Flowering Locus T protein in the leaves that triggers flowering. Once the protein is formed, the substance that will leave the leaves to the shoot, the cells have differentiated into leaf or flower. In the area, protein molecular changes by sending the cell into the path that would be flowers. 

Changes in day length at a particular season tells the plant that the season has changed. Like humans, plants also have such a circadian clock and is used to measure changes in day length. This clock synchronizes the biological processes in the human body, animals, to plants for 24 hours. 

Imaizumi also investigated FKF1 protein, are thought to play an important role in the mechanism that makes the seasons changing and the plants know when to flower.  

Pictured are Takato Imaizumi
and Young Hun Song in the
Takato plant lab at  the University
of Washington. (Picture from:  
http://www.eurekalert.org/)

"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."

This system keeps plants from flowering when it's a poor time to reproduce, such as the dead of winter when days are short and nights are long.

The new findings come from work with the plant Arabidopsis, a small plant in the mustard family that's often used in genetic research. They validate predictions from a mathematical model of the mechanism that causes Arabidopsis to flower that was developed by Andrew Millar, a University of Edinburgh professor of biology and co-author of the paper.

"Our mathematical model helped us to understand the operating principles of the plants' day-length sensor," Millar said. "Those principles will hold true in other plants, like rice, where the crop's day-length response is one of the factors that limits where farmers can obtain good harvests. It's that same day-length response that needs controlled lighting for laying chickens and fish farms, so it's just as important to understand this response in animals.

"The proteins involved in animals are not yet so well understood as they are in plants but we expect the same principles that we've learned from these studies to apply." *** [LIVESCIENCE | EUREKALERT! | TJANDRA | KORAN TEMPO 3896]

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