SKIP is essential for the splicing of SEF pre-mRNA. a Locations of the primer pairs used to amplify mature SEF mRNA and its alternatively spliced isoforms. SEF-Aa, SEF-Ab, SEF-Ac, SEF-Ad (SEF-A), and SEF represent the mature mRNA, SEF mRNA containing the first intron, SEF mRNA containing the second intron, alternatively spliced mRNA containing the first and second introns from the SEF-A fragment, and all isoforms of SEF. UTR represents untranslated region. I1, I2, and I3 represent introns 1, 2, and 3. E1, E2, E3, and E4 represent exons 1, 2, 3, and 4. The black arrows indicate the location of primers. b, c, e, f The levels of mature SEF mRNA and its alternatively spliced isoforms in WT plants, skip-1, and the skip-1 complemented transgenic lines described in Fig. 1 under LD (b, e) and SD (c, f) conditions as determined by semi-RT-PCR (b, c) or qRT-PCR (e, f). d The levels of mature SEF mRNA and its alternatively spliced isoforms in WT and skip-1 plants at different times across the circadian cycle as determined by semi-RT-PCR. ZT indicates zeitgeber time or the time under continuous light. The values in e and f are the mean ± s.d.