Alternative promoter usage of per3 under cold stress. (A) Read coverage at per3 locus. The top panel shows the read coverage of each sample at per3 locus and the bottom panel indicates the structure of per3 transcripts. (B) The relative abundance of per3 isoforms under cold stress. (C) Promoter switching of per3 under cold stress. (D) qPCR validation of the alternative promoter usage for per3. Error bars indicate standard deviation (n = 3).