MADISON - Winter is no time to flower, which is why so many plants have evolved the ability to wait for the snow to melt before investing precious resources in blooms.
Waking up to flower as the warmer, longer days of spring arrive - and the risk of a damaging frost recedes - requires a process called vernalization, in which flowering is blocked until the plant senses a sufficient cold spell. Researchers at the University of Wisconsin-Madison have identified a gene that keeps grasses from entering their flowering cycle until the season is right, a discovery that may help plant breeders and engineers get more from food and energy crops.
"For many plants - some varieties of wheat are a good example - it's advantageous to get established in the fall but avoid flowering before it gets really cold," says Rick Amasino, a UW-Madison professor of biochemistry and genetics. "By becoming established in the fall, such plants can take full advantage of the window of the growing season when it opens in the spring."
Much has been done to identify genes involved in flowering, including one in grasses called VRN1 that helps get the vernalization ball rolling by spurring groups of other genes into action. But just what keeps VRN1 in check, so flowering does not occur in the fall or in a winter warm spell, was unclear until Amasino, postdoctoral researcher Daniel Woods and others began putting a small Mediterranean grass called Brachypodium, or false purple brome, through false cold seasons in lab refrigerators.
"Getting at the genetics underlying complex processes is difficult in many crop species, so we've used a small plant with a compact genome as a model to get at the molecular underpinnings of how a vernalization requirement is established," says Woods, first author on the study published Monday (June 5, 2017) in the journal Proceedings of the National Academy of Sciences. "What we found is a gene that represses the VRN1 gene prior to winter."