51. Among the following which gene product migrates from leaves to shoot meristem during

transition of shoot meristem into floral meristem?
(1) Flowering locus T                             (2) Flowering locus D
(3) Leafy                                                       (4) Apetala 1

 

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Introduction

The transition from vegetative growth to flowering in plants is controlled by a mobile signaling molecule encoded by the Flowering Locus T (FT) gene. FT protein is synthesized in the leaves in response to environmental cues and travels to the shoot apical meristem (SAM), where it initiates floral meristem identity and flower formation.

FT as the Mobile Flowering Signal

• FT protein is produced in the phloem companion cells of the leaves under inductive photoperiods.

• It travels through the phloem to the shoot apex where it interacts with transcription factor FD to activate flowering genes such as APETALA1 (AP1).

• The movement of FT from leaves to SAM is critical for the timing and location of floral initiation.

Other Gene Products

• Flowering locus D is not a mobile signal; it functions in floral induction pathways but does not move to the meristem.

• LEAFY and APETALA1 are floral meristem identity genes expressed at the SAM, downstream of FT signaling, and do not migrate from leaves.

Biological Significance

• FT protein is considered the molecular basis for “florigen,” the classic flowering hormone sensed by the shoot apex.

• This discovery clarified the mechanism linking leaf photoperiod perception with floral initiation at the meristem.

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Summary Table: Genes and Their Roles in Floral Transition

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Conclusion

The Flowering Locus T (FT) gene product is the mobile signal that moves from leaves to the shoot apical meristem to trigger flowering, while Flowering Locus D, LEAFY, and APETALA1 function locally at the meristem.