‘Fiona’ Gene Controls Flower’s Physiologic Clock

By Cho Jin-seo
Staff Reporter

Scientists have found a new gene that regulates the daily and yearly physiological cycles of flowering and seeding.

POSTECH researchers, led by Nam Hong-gil and Kim Jeong-sik, said that they named the gene FIONA1 after the heroine in the popular animation ``Shrek.'' In the animation, princess Fiona is human by day but becomes an ogress at sunset. Fiona also sounds similar to the term ``flowering'' in Korean.

The research is a foundation for further discoveries of the plants' clock systems, the team said. To study the gene, the POSTECH team used mutated cress, a species of weed widely used in such experiments because of its short seeding cycle and small genome size.

``We have identified the novel clock component, FIONA1 (FIO1), which is closely associated with the central oscillator and is critical to maintaining the correct period length, but it is not necessary for maintaining the amplitude of circadian rhythm,'' the researchers said in the paper published on Plant Cell magazine last week.

The circadian rhythm, which refers to the 24-hour cycle of plants and animals and other living organisms, is believed to be corresponding to environmental factors such as temperature and light. But certain cycling rhythms continue to appear even under constantly controlled conditions. Furthermore, plants use their circadian clock to measure changes in day length, in order to determine the time when it should flower or seed.

The POSTECH team used genetic mutations of the cress for the identification and functional characterization of various components that make the internal clock. As a result, they found FIONA1, which acts as a clock that controls the plant's internal clock separately from amplitude and robustness of other conditions of the circadian period.

The team said that it is just an opening to further discoveries. ``Despite such progress in elucidating the regulatory mechanisms underlying circadian systems in plants, our understanding remains very limited and requires the further identification and functional study of regulatory elements,'' the paper said.

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