Fig. 1. SUF4 is required for the late-flowering phenotype of FRI and is alternatively spliced. (A,B) The effect of suf4 mutations on flowering time in the indicated genetic backgrounds. (A) Plants were photographed at similar stages of development (e.g. at the opening of the first flowers). (B) Bars represent the total number of leaves (rosette and cauline) formed by the primary shoot apical meristem. Black and gray bars represent plants grown under long days; white and cross-hatched bars represent plants grown under short days. Plants represented by gray and cross-hatched bars were cold-treated for 30 days before planting. Error bars represent the s.d. (C) Genomic structure of SUF4. Exons are indicated by open boxes; filled circles indicate sites of alternative splicing. (D) RT-PCR of SUF4 and a schematic drawing of the three splice variants of SUF4.