Memory molecule causes spring bloom

U. TEXAS-AUSTIN (US) — Plants bloom in spring because of a key molecule that helps them remember the long period of cold that is winter.

“Plants can’t literally remember, of course, because they don’t have brains,” says Sibum Sung, assistant professor of molecular cell and developmental biology at University of Texas at Austin. “But they do have a cellular memory of winter.”

Plants become competent to flower after a period of cold by a process called vernalization. Though it is common for many plants adapted to temperate climates, including crops like winter wheat, scientists have only recently begun to understand the process’s genetic and molecular underpinnings.

Sung and postdoctoral fellow Jae Bok Heo have now discovered that a long, non-coding RNA molecule, named  Coldair is required for plants to set up a memory of winter.

The work is published in Science Express.

The researchers say that in fall, a gene called FLC actively represses floral production because a random fall bloom in fall could be a waste of precious energy.

But after a plant has been exposed to 20 days of near-freezing temperatures, coldair becomes active and silences the FLC gene. The process is complete after about 30 to 40 days of cold. With the FLC silenced as temperatures warm in the spring, other genes are activated that initiate blooming.

The next step, Sung says, is figuring out how plants actually sense cold temperatures. Researchers believe that their findings could lead to crop improvements and will be important as climate changes alter the length of the winter season.

The National Science Foundation supported the research.

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