DSB repair in Arabidopsis Col0 and atlig1-RNAiA and atlig1-RNAiB lines determined by neutral comet assay. (A) Time course of DSB repair during 1-hour repair period. Background DNA damage in untreated (control) seedlings and damage after 1 hour treatment with 30 μg/ml bleomycin (t = 0) is similar in all lines. Defects in DSB repair is manifested by DNA remaining in comet tails (% tail DNA). (B) Kinetics of DSB repair measured over the first 60 min show biphasic kinetics. Percents of DSB remaining were calculated from % tail DNA as described in Comet data evaluation.