Transient activity of the florigen complex during the floral transition in Arabidopsis thaliana

Abstract

FLOWERING LOCUS T (FT) is an essential component of florigen in Arabidopsis thaliana. Transcription of FT is induced in leaves, and the resulting FT protein is transported to the shoot apex, in which it initiates floral development. Previous analyses suggest that, together with the b-ZIP transcription factor FD, FT regulates the transcription of downstream targets such as APETALA1 (AP1) in floral anlagen. However, conclusive in vivo evidence that FT is transported to the shoot apex to form an FT-FD complex is lacking. Here, using an innovative in vivo imaging technique, we show that the FT-FD complex and AP1 colocalise in floral anlagen. In addition, the FT-FD complex disappears soon after the floral transition owing to a reduction in FD transcripts in the shoot apex. We further show that misinduction of FD activity after the transition leads to defective reproductive development. Taken together, our results indicate that the FT-FD complex functions as a transient stimulus and imply that a regulatory mechanism exists during the floral transition that reduces FT-FD complex levels via modulation of FD expression.

RNA-seq Analysis of Meristem Cells Identifies the <i>FaFT3</i> Gene as a Common Floral Inducer in Japanese Cultivated Strawberry

“…LEAFY plays a pivotal role in floral induction, whereas AP2 directly induces the transcription of the floral repressor AGAMOUS-LIKE 15 and represses the expression of floral activators such as SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (Blázquez et al, 1997;Weigel et al, 1992;Yant et al, 2010). Similarly, it was recently shown that FD transcription was reduced soon after the floral transition in Arabidopsis (Abe et al, 2019). However, as the other FD homologue (FANhyb_rscf00000064.1.g00025.1) was stably expressed during the floral transition (Table 1), additional experiments are needed to clarify whether the FT-FD complex functions as a transient stimulus for floral initiation in cultivated strawberries.…”

Abscisic Acid and Flowering Regulation: Many Targets, Different Places

“…The key floral genes FD and FD PARALOGUE ( FDP ) belong to group A of Arabidopsis bZIPs, totaling 13 members. Consistent with its established role in flowering, FD controls the expression of floral regulators like SOC1 , LEAFY , FRUITFULL , and APETALA1 [ 24 , 85 , 86 , 87 ] by direct binding at their respective promoters [ 87 ]. FD and FDP also share several downstream targets that are ABA- and water stress-related, including other members of group A bZIPs such as ABF3 and DPBF1 / ABI5 , the PP2Cs ABI1 and HAB1 , the ABA catabolic gene CYP707A2 , and proteostasis-related genes ABI FIVE BINDING PROTEIN 2 ( AFP2 ) and AFP4 ( Figure 1 ).…”

Morphological, Physiological, and Molecular Responses of Sweetly Fragrant Luculia Gratissima During the Floral Transition Stage Induced by Short-day Photoperiod

“…The photoperiod pathway is involved in plant response to changes to day length and circadian rhythm, making it one of the most important owering regulation pathways. In the photoperiod pathways of many plants, the bZIP transcription factor FD forms a transient complex in SAMs with the FT protein from leaves to induce the expression of oral meristem identity genes, thereby promoting oral transition [47]. In this study, FD, AP1, FUL, and AGL8 were highly expressed in SD10 and SD13 (Fig.…”