Table 1.
Some mutations affecting flowering in tomato.
Table 2.
Tomato double mutants produced and analysed in this study.
Figure 1.
Flowering time (expressed as number of leaves below the first inflorescence) of tomato double mutants.
(A) j∶sft; (B) s∶sft; (C) j∶fa; (D) s∶fa; (E) j∶s; and (F) fa∶sft. Values followed by a same letter (a, b, or c) are not statistically different (P<0.05). Genotype abbreviations: AC, Ailsa Craig WT; fa, falsiflora; Hz, Heinz WT; j, jointless; Pl, Platense WT; RR, Rheinlands Rhum WT; s, compound inflorescence; sft, single flower truss. The j mutant is in AC background in A and C, in Hz background in E.
Figure 2.
Inflorescence phenotype of tomato mutants.
(A–C) Ailsa Craig WT; (D) and (E) s mutant; (F) and (G) j mutant; (H) and (I) j∶s double mutant; (J–L) fa mutant; (M–O) s∶fa double mutant; (P) and (Q) j∶fa double mutant. In microscopic pictures, colour bars show the clefts that occurred sequentially when new meristems were initiated to build-up the inflorescence. Red: 1st; yellow: 2nd; green: 3rd; blue: 4th; purple: 5th. Dots of same colours show the corresponding branching in macroscopic inflorescence pictures. Pictures K and N zoom in J and M, respectively, to show clumps of IMLs in the inflorescences (arrows). Genotype abbreviations: AC, Ailsa Craig WT; fa, falsiflora; j, jointless; s, compound inflorescence. Annotations: AX, axillary meristem; F, flower; FM, flower meristem; IM, inflorescence meristem; IML, IM-like; L, leaf; SAM, shoot apical meristem; SYM, sympodial meristem; VM, vegetative meristem. Bars = 100 µm except in K and N where bars = 1 mm.
Figure 3.
Detection of FA and J transcripts by in situ hybridization in longitudinal sections of tomato shoot apices.
(A–C) FA expression at (A) vegetative, (B) transitional and (C) floral stages of Ailsa Craig WT. (D) FA expression in the inflorescence of the j mutant. (E–G) J expression in apices at (E) vegetative and (F–G) floral stages of WT. (H) J expression in the inflorescence of the fa mutant. F, flower; FM, flower meristem; IM, inflorescence meristem; IML, IM-like; L, leaf; SAM, shoot apical meristem; VM, vegetative meristem. Bars = 100 µm.
Figure 4.
Inflorescence phenotype of tomato mutants.
(A) and (B) Inflorescence of sft mutant showing several flowers; (C) and (D) Inflorescence of sft mutant with solitary flower; (E–G) s∶sft double mutant; (H) and (I) fa∶sft double mutant; (J) and (K) j∶sft double mutant. In microscopic pictures, colour bars show the clefts that occurred sequentially when new meristems were initiated to build-up the inflorescence. Red: 1st; yellow: 2nd, green: 3rd. Dots of same colours show the corresponding branching in macroscopic inflorescence picture. In C and J, arrows point at leaf-like sepals. Genotype abbreviations: fa, falsiflora; j, jointless; s, compound inflorescence; sft, single flower truss. Annotations: F, flower; FM, flower meristem; IM, inflorescence meristem; IML, IM-like; L, leaf; S, shoot; SYM, sympodial meristem; VM, vegetative meristem. Bars = 100 µm.
Figure 5.
Hypothetical model of genetic interactions shaping the inflorescence of tomato.
At floral transition, the SAM forms a flower meristem (FM) and a lateral meristem arises adjacently. JOINTLESS (J) and an unknown target (X) of the systemic SINGLE FLOWER TRUSS (SFT) protein prevent early FM maturation in the lateral meristem and so allow an inflorescence meristem (IM) fate. This involves repression of the FM identity gene FALSIFLORA (FA) by J in the IM.