| Process/Function | Mechanism/Key partners | Subcellular/tissue location (production, transport route, site of action) | Key recent evidence (2023–2024) with paper, DOI/URL, and publication month/year | Notable quantitative data points |
|---|---|---|---|---|
| Target identity / core molecular role | Arabidopsis **FT** is the canonical **florigen** and a **PEBP-family** protein; it does not bind DNA directly but acts as a transcriptional co-regulator with FD-class bZIP factors (pqac-00000008, pqac-00000011, pqac-00000012) | Produced in leaf vasculature, then acts at the shoot apical meristem (SAM) (pqac-00000011, pqac-00000012) | **Maple et al.** *Plant Physiology* (Feb 2024), DOI: 10.1093/plphys/kiae109, https://doi.org/10.1093/plphys/kiae109; **Takagi et al.** *Plant Communications* (May 2023), DOI: 10.1016/j.xplc.2023.100552, https://doi.org/10.1016/j.xplc.2023.100552; **Colleoni et al.** *J Exp Bot* (Mar 2024), DOI: 10.1093/jxb/erae112, https://doi.org/10.1093/jxb/erae112 (pqac-00000008, pqac-00000011, pqac-00000012) | No catalytic activity reported; FT acts as a mobile signaling protein rather than an enzyme/transporter (pqac-00000008, pqac-00000011) |
| Photoperiodic flowering induction | CO directly activates **FT** transcription in leaves; FT is the key floral pathway integrator under long days (pqac-00000011, pqac-00000012) | Strong expression in **phloem companion cells** of distal leaves; signal ultimately reaches SAM (pqac-00000011, pqac-00000012) | **Takagi et al.** *Plant Communications* (May 2023), https://doi.org/10.1016/j.xplc.2023.100552; **Maple et al.** *Plant Physiology* (Feb 2024), https://doi.org/10.1093/plphys/kiae109; Maple Figure 1 schematic (pqac-00000011, pqac-00000012, pqac-00000013) | Typical lab LD = **16 h light / 8 h dark**; FT induction correlates with flowering when day length exceeds **~12 h**; CO mRNA peaks about **16 h after dawn** in LDs (pqac-00000011, pqac-00000012) |
| Long-distance mobile florigen signal | FT protein is loaded into sieve elements and carried through the **phloem** to the SAM; movement is regulated, not passive diffusion (pqac-00000000, pqac-00000001, pqac-00000012) | Production: leaf companion cells; route: companion cell → sieve element → phloem stream → shoot apex; site of action: SAM (pqac-00000001, pqac-00000012) | **Tsuji & Sato** *Plant and Cell Physiology* (Jan 2024), DOI: 10.1093/pcp/pcae001, https://doi.org/10.1093/pcp/pcae001; **Maple et al.** *Plant Physiology* (Feb 2024), https://doi.org/10.1093/plphys/kiae109 (pqac-00000001, pqac-00000012) | Grafting/induction experiments indicate leaf-produced FT can reach the SAM in about **12 h** (pqac-00000001) |
| Controlled export and trafficking | Export from companion cells requires **FTIP1**; **QKY** and **SYP121** facilitate export via an MCTP-SNARE/endosomal trafficking route; long-distance trafficking is regulated by **NaKR1** (pqac-00000000, pqac-00000002, pqac-00000012) | Companion cell ER/plasmodesmata interface, then sieve elements/phloem stream toward the apex (pqac-00000000, pqac-00000012) | **Maple et al.** *Plant Physiology* (Feb 2024), https://doi.org/10.1093/plphys/kiae109; **Colleoni et al.** *J Exp Bot* (Mar 2024), https://doi.org/10.1093/jxb/erae112 (pqac-00000000, pqac-00000002, pqac-00000012) | Late flowering in **ftip1/qky/mctp6** loss-of-function backgrounds is consistent with impaired FT transport, though no single numeric effect size is given in the excerpts (pqac-00000002) |
| Site and mode of action at the SAM | FT forms a **floral activation complex** with **FD/FD-related bZIPs** and **14-3-3 proteins**, promoting floral target genes such as **AP1** and **LFY**; **TFL1** antagonizes FT by competing for FD-associated function (pqac-00000005, pqac-00000006, pqac-00000012) | FT accumulates in the shoot apex; activity is centered in/around the SAM and floral anlagen rather than peripheral leaf tissues (pqac-00000001, pqac-00000012) | **Takagi et al.** *Plant Communications* (May 2023), https://doi.org/10.1016/j.xplc.2023.100552; **Tsuji & Sato** *Plant Cell Physiology* (Jan 2024), https://doi.org/10.1093/pcp/pcae001; **Maple et al.** *Plant Physiology* (Feb 2024), https://doi.org/10.1093/plphys/kiae109 (pqac-00000001, pqac-00000005, pqac-00000006, pqac-00000012) | Imaging with SUC2::FT-GFP showed central accumulation at the apex; quantitative value not given in excerpt, but SAM localization is emphasized experimentally (pqac-00000001) |
| Expanded FT-signaling transcription factor network | In addition to FD, **AREB3** redundantly mediates FT signaling at the SAM; multiple florigen-interacting bZIPs contribute, refining the classic FT–FD-only model (pqac-00000003, pqac-00000007) | AREB3 expression overlaps FD in the SAM, where FT-dependent transcriptional reprogramming occurs (pqac-00000003) | **Martignago et al.** *PLOS Genetics* (May 2023), DOI: 10.1371/journal.pgen.1010766, https://doi.org/10.1371/journal.pgen.1010766 (pqac-00000003, pqac-00000007) | Redundant genetic effects reported qualitatively: fd areb3 and higher-order bZIP mutant combinations flower later than single mutants; no exact flowering-day values in excerpt (pqac-00000003) |
| Environmental modulation beyond photoperiod | FT expression is also promoted by **PIF4/PIF5/PIF7** under warm conditions; thermosensory phyB-state changes can increase FT induction (pqac-00000000, pqac-00000012) | Leaf tissues where FT is transcriptionally induced before systemic transport (pqac-00000012) | **Maple et al.** *Plant Physiology* (Feb 2024), https://doi.org/10.1093/plphys/kiae109 (pqac-00000000, pqac-00000012) | Elevated temperature example in review: **27 °C** promotes PIF/CO-mediated FT induction relative to optimal ambient conditions (pqac-00000012) |
| Transport/localization model support from recent schematic synthesis | Recent synthesis places FT at the center of converging flowering pathways and explicitly depicts transport from leaf to SAM, where floral identity genes are activated (pqac-00000013) | Leaf source tissue → mobile signal → green schematic SAM with floral integrators/identity genes (pqac-00000013) | **Maple et al.** Figure 1, *Plant Physiology* (Feb 2024), https://doi.org/10.1093/plphys/kiae109 (pqac-00000013) | Figure summarizes pathway convergence rather than providing new numeric measurements; useful as a current consensus model (pqac-00000013) |


*Table: This table summarizes the functional annotation of Arabidopsis thaliana FT (UniProt Q9SXZ2), focusing on molecular role, transport, site of action, partners, and recent 2023–2024 evidence. It is useful as a compact evidence-backed reference for FT biology and annotation.*