Features of LSF1 and the lsf1 mutant. A, For LSF1 and SEX4 proteins, the predicted positions of the putative carbohydrate-binding domain (CBD) and the DSPc are indicated as boxes, and the conserved motifs of the DSPc domains are indicated. B, Exon and intron structure of the LSF1 gene, showing the location of the T-DNA insertion in the lsf1-1 mutant 104 bp upstream of the ATG start codon. Black boxes indicate exons; gray boxes are the 5′ and 3′ untranslated regions; the white box is the T-DNA insertion. C, LSF1 mRNA levels in wild-type and mutant plants. Total RNA extracted from wild-type (lanes 1 and 2) and homozygous lsf1 mutant (lanes 3 and 4) plants was analyzed by RT-PCR. Reactions contained primers amplifying the following products: a TUBULIN 1-kb fragment (positive control; lanes 1 and 3) and a LSF1 1.7-kb fragment (lanes 2 and 4). D, LSF1 protein levels in wild-type and mutant plants. Immunoblot analysis was on leaf extracts from Col-0 (lane 1), a wild type selected from a population segregating for lsf1-1 mutants (lane 2), lsf1-1 (lane 3), sex4-3 (lane 4), and lsf1-1/sex4-3 (lane 5) using an antiserum raised to a LSF1 peptide. The left lane is a molecular mass marker. The arrowhead indicates a band of approximately 64 kD, the appropriate mass for the mature LSF1 protein.