Insertion of 35S enhancer in the promoter region of AGL20 causes overexpression. (A) DNA gel blot analysis showing the polymorphism between fsu1-1D FRI FLC (fsu1) and FRI FLC (FRI). (B) Diagram of genomic organization showing the insertion of 35S enhancer into the AGL20 region in fsu1-1D FRI FLC. LB and RB are left border and right border of T-DNA, respectively. A bar represents the DNA fragment obtained by plasmid rescue and used for DNA gel blot analyses. (C) RT-PCR result for SAP18, AGL6, and AGL20 in the leaves of 3-week-old Columbia (Col), FRI FLC (FRI), and fsu1-1D FRI FLC (fsu1). The β-tubulin gene (TUB) was amplified as a quantitative control. (D) The amino acid sequence of AGL20. MADS, I, and K domains are indicated. (E) Neighbor-joining phylogenetic tree for Arabidopsis MADS-domain proteins.