By Marian Schubert
The arrival of winter marks not only a change in weather, temperature, and day length, but also a change in our activity and behavior. The social outdoor events and trips to the beach over summer soon become a distant memory, and we ready ourselves for more solitary evenings indoors with a hot drink and a good book. Things slow down.
The same can be said for winter varieties of cereal crops such as wheat and barley. After seeds are sowed in late summer and autumn, closely followed by a burst of activity through germination and early growth, these grasses settle down for a period of winter dormancy where growth dramatically slows and reproduction is blocked during the cold months.
Vernalization—the 'when to flower' signal
During the dormancy phase, a critical process called vernalization takes place within the plants, triggered by prolonged exposure to wintery conditions such as low temperatures. Vernalization involves a range of internal signaling events that ultimately ensure flowering is postponed during the coldest season and occurs at the optimal timepoint in the spring and summer.
Without vernalization, the dormancy-induced block on reproduction is not lifted, and plants will not flower or produce grain when conditions become favorable again.
Most research into the causes and mechanisms of vernalization has focused on so-called chilling vernalization (induced by prolonged winter cold). However, in our recent study published in the New Phytologist, we shed light on the less well-studied short day vernalization (SDV), triggered by shortening days in the autumn and winter.
How the two different types of vernalization function and their relative importance for well-timed flowering is not well understood, likely because major winter crops are typically exposed to both short days and cold temperatures in the field. This is something that may be changing as the climate warms.
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