Circadian Clock- and Transcription-controlled Genome-wide Excision Repair of UV Damage in Arabidopsis

We used the recently developed Excision Repair-sequencing (XR-seq) method to study genome-wide repair of UV-induced DNA damage in Arabidopsis. We found that the repair of cyclobutane pyrimidine dimers for a large fraction of the genome is controlled by the joint actions of the circadian clock and transcription by RNA polymerase II. Arabidopsis has a relatively compact genome, and a large fraction of the genes are controlled by the circadian clock. Our data on the interface of these two global regulatory systems reveal very strong repair preference of the transcribed strands of Arabidopsis genes, 10 to 30% of which are circadian time-dependent. Thus, throughout the day, Arabidopsis exhibits enormous dynamic range in repair to cope with exposure to sunlight. Examination of excision repair throughout the circadian cycle with 2 experiments each of which having 8 samples collected at ZT2, ZT5, ZT8, ZT11, ZT14, ZT17, ZT20, ZT23