Research conducted by scientists from John Innes Centre (JIC), in collaboration with colleagues in Hungary and France, shows that vernalization is influenced by warm conditions as well as cold, and a much wider temperature range than previously thought.

Vernalization is the process by which plants require prolonged exposure to cold temperature before they transition from the vegetative state to flower. The study began as an exploration into how variance in ambient temperatures might influence flowering regulation in winter wheat. But it unexpectedly uncovered an "extreme vernalization response". Before the study, it was thought that vernalization only happened up to a maximum of about 12°C. The researchers found that the true temperature was much higher.

The researchers exposed a panel of 98 wheat cultivars and landraces and to temperatures ranging from 13 to 25°C in controlled environments. Normally, when vernalization is complete, plant growth is accelerated under warm temperatures. However, one cultivar, named Charger, did not follow this standard response. Gene expression analysis showed that the wheat floral activator gene (VRN-A1) was responsible for this trait. Further experiments showed that expression of genes that delay flowering is reactivated during high temperatures of up to 24 °C, showing that vernalization is not only a consequence of how long the plant experiences continuous cold.

For more details, read the press release from JIC.