Gene expression analysis of hypoxia-responsive genes (ADH, PCO1, PGB1, LBD41, WIP4, HUP7, HRA1, and PCO2) in a time-course experiment using 6-day-old Arabidopsis Col-0 seedlings. Samples were collected every 4 h for 2 days. The mRNA levels of genes were measured by RTqPCR, and the data on the y-axis are expressed relative to ZT4 (ZT4 = 1). The x-axis represents zeitgeber time (ZT0, the time when the lights are switched on). The data represent the mean standard error (SE) of three biological replicates. Overall levels of gene expression in the daytime (D) and nighttime (N) estimated by calculation of area under the curve. Student’s t-test was performed, and asterisks indicate statistically significant differences of gene expression levels between day and night (*P< 0.05, **P< 0.01, ***P< 0.001).
