Figure 1.

Analysis of pTFL1:GUS reporter lines in genetic backgrounds with modified LFY activity. (A) Summary of the experiments performed to test the functional relevance of the LFY binding sites in the 3′ region of the TFL1 promoter. The activity of 2 pTFL1:GUS constructs was assayed in pHS:LFY-VP16 seedlings: one with the full length TFL1 promoter (2.2 kb of the 5′ region plus 4.6 kb of the 3′) and one with a truncated version of the promoter lacking the LFY binding region (2.2 kb of the 5′ region plus 2.7 kb of the 3′, ΔLFY). ‘Ectopic GUS (+)’ denotes staining in roots, cotyledons and developing leaves after a heat-shock treatment. Growth conditions, heat-shock treatments (incubation for 3 h at 37°C during 3 consecutive days) and GUS staining were conducted as described previously.¹⁸ (B-D) Representative images of pHS:LFY-VP16 seedlings containing a pTFL1:GUS reporter and stained for GUS: (B) reporter activity of the full length TFL1 promoter in a pHS:LFY-VP16 seedling grown under control conditions without heat-shock, (C) reporter activity of the full length TFL1 promoter in a pHS:LFY-VP16 seedling after heat-shock, (D) reporter activity of the truncated version of the TFL1 promoter (ΔLFY) in a pHS:LFY-VP16 seedling after heat-shock. Asterisks point to the position of the SAM. (E-F) Reporter activity of the full length TFL1 promoter in representative inflorescence apices of wild type (accession Landsberg erecta) (E), lfy-26 (F) and ap1–1 (G) plants. The inset in (F) shows the terminal carpelloid structure in lfy-26 shoots. Arrows in the main panels point to the position of the SAM. GUS staining was conducted as described previously.²³