Fig. 1. Molecular characterization of the tt19-8 phenotypic suppressors S1-S8 and corresponding anthocyanin accumulation.

a Structure of the RDR6 gene indicating the position and nature of the EMS-induced mutations for the S1, S8, S4, and S2 suppressors. The images show 4-day-old seedlings grown in AIC and accumulating various levels of anthocyanins evaluated by absorbance at 532 nm (A₅₃₂), and normalized to the dry weight of the seedlings. The levels present in Col-0 were taken as 100%. b Structure of the SGS3 gene indicating the mutations for the S3, S5, and S6 suppressors. All three suppressors showed similar levels of anthocyanins in AIC and the same mutation, which abolishes a splicing acceptor site. The genome browser image on the top right shows the reads obtained in RNA-seq experiments for S5, and the region demonstrating the use of an alternate splicing acceptor site in the S5 mutant is shown expanded on the lower image. c Structure of the DCL4 gene indicating the mutation for the S7 suppressor, which abolishes a splicing donor site, as evidenced by the genome browser images comparing the RNA-seq reads of Col-0, tt19-8, and S7. Similar anthocyanin quantification results were obtained from at least three independently repeated experiments. Bar, 400 μm.