Positional cloning of muse16-1. (A) Map position of muse16 on chromosome 2. The BAC clones and numbers of recombinants from the mapping population are indicated. (B) Gene structure of MUSE16 (AT2G37150). Boxes indicate exons and lines indicate introns. Gray indicates the untranslated region, and black indicates coding regions. The asterisk indicates the site of the G-to-A mutation in muse16-1. The arrow indicates the position of the T-DNA insertion site in Salk_021643. (C) cDNA sequence comparison between wild type (WT) MUSE16 and the muse16-1 mutant. In muse16-1, the first G of the 7th exon is spliced out due to the G-to-A mutation at the intron–exon splice junction, which creates a new 3´ splice site, resulting in a reading frame shift. (D) The predicted protein domain of MUSE16. The black box represents the RING domain. The asterisk indicates where the protein truncation occurs due to the mutation in muse16-1.