Modification of the circadian clock adapts barley to short growing seasons
Flowering during the correct season is essential for plants to ensure reproductive success. Flowering too late or early during the year could damage the developing flowers that are sensitive to temperature. Therefore, plants use various environmental factors to estimate the time of the year to synchronize their development accordingly. One such factor, invariably connected to seasonality, is day length, that is, the number of hours of daylight during the day. The daily rhythms of day and night and their changes throughout the year are anticipated and governed by the plant’s internal (circadian) clock. It directly influences the so-called photoperiodic pathway, which regulates flowering in response to day length.
Adjusting crop response and flowering to different day lengths is crucial for adapting crops to various cultivation areas, climates, and photoperiods. In our publication, we identified a novel genetic regulator of flowering time in the agronomically highly important cereal crop barley, underlying the early maturity 7 (eam7) locus. A spontaneous mutation in the gene LIGHT-REGULATED WD1 (LWD1) enables barley plants to accelerate their development in days with shorter photoperiods, even though they usually require days with more than 12 hours of light to flower. The lwd1mutation renders barley almost insensitive to photoperiod, allowing for cultivation in various latitudes and marginal environments. Additionally, plants carrying this mutation exhibit increased floral fertility, which is typically reduced in non-optimal day lengths. We could show that the mutation in LWD1 alters the circadian clock of the plant, presumably by affecting the processing of light signals that are used to synchronize the circadian clock. The resulting imbalance between the internal rhythmicity of diverse physiological processes and the external rhythmicity of light and dark periods reduces the plant’s dependence on photoperiod, thus overcoming the limiting factor of short day lengths.
Text and photo: Gesa Helmsorig