Fig. S2.

Phenotypes of sp1 mutants. (A) SP1 gene structure. The open box represents the UTR; the black boxes represent exons; the solid line represents the intron. T-DNA insertion sites in the mutants are indicated. Arrows indicate the primers used in RT-PCR. (B) RT-PCR analysis of RNA from 4-wk-old sp1 T-DNA insertion mutant lines. Two individual plants were analyzed for each mutant. P, wild-type; N, water only (negative control). Ubiquitin 10 (UBQ10) was used as a loading control. White lines separate noncontiguous gel lanes. The negative control for UBQ10 in sp1-2 was run on a separate gel. (C) Four-week-old sp1 mutants. (D) 2,4-DB response assays of 7-d-old light-grown seedlings. Seedlings were grown on MS medium supplemented with 0.5% sucrose and various concentrations of 2,4-DB. The average root length normalized to the data obtained from plants grown on 0.5% sucrose medium without 2,4-DB is shown. Error bars indicate SEM; n = 3 (>30 seedlings for each biological replicate). **P < 0.01; *P < 0.05 from wild type. (E) RT-PCR analysis of RNA from a 4-wk-old 35Spro: SP1 line. P, wild-type; N, negative control (water only). Ubiquitin 10 was used as a loading control. White lines separate discontinuous gel lanes. (F) Epifluorescence images showing peroxisome morphology in mesophyll cells of 2-wk-old plants expressing the peroxisome marker YFP-PTS1. (Scale bar, 10 μm.) drp3A-2 (SALK_147485), which is defective in fission, is included as an example of abnormal peroxisome morphology.