Fig 6. Dynamic response of circadian oscillations to daylength shifts.
Barley seedlings (cv. Sonja) were germinated and grown in 8 hour or 16 hour days, for 14 days (second leaf stage), with dawn synchronous in the two daylengths. On the 14th day plants were shifted from 8 to 16 hour days and vice versa. Shifts occurred 8 hours after dawn shortly before the onset of darkness in the short-day condition. Gene expression was then assayed by qRT-PCR, normalized to ACTIN with 3 biological repeats, in the plants shifted to different daylengths and in control plants maintained in the same daylength. The 8 hour day treatment (blue line) is compared to 16 hours (red line) at the left hand side. The 16 hour day treatment is compared to plants shifted from 16 to 8 hour daylength (long to short days, orange line), centre panel. The 8 hour daylength is compared to seedlings shifted to 16 hours (short to long days, purple line) on the right hand side. Error bars show standard error. * indicates Student’s T-test P<0.05, **P<0.01, ***P<0.001 between treatments for the relevant timepoint.