NUCLEAR FACTOR Y, Subunit A (NF-YA) Proteins Positively Regulate Flowering and Act Through FLOWERING LOCUS T.

Chamindika L Siriwardana,Daniel S Jones,Nerina Gnesutta,Ben F Holt,Roberto Mantovani,Roderick W Kumimoto,Zachary A Myers,Gloria K Muday

doi:10.1371/journal.pgen.1006496

Chamindika L Siriwardana, Daniel S Jones + Show 6 more

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https://doi.org/10.1371/journal.pgen.1006496

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Abstract

Photoperiod dependent flowering is one of several mechanisms used by plants to initiate the developmental transition from vegetative growth to reproductive growth. The NUCLEAR FACTOR Y (NF-Y) transcription factors are heterotrimeric complexes composed of NF-YA and histone-fold domain (HFD) containing NF-YB/NF-YC, that initiate photoperiod-dependent flowering by cooperatively interacting with CONSTANS (CO) to drive the expression of FLOWERING LOCUS T (FT). This involves NF-Y and CO binding at distal CCAAT and proximal “CORE” elements, respectively, in the FT promoter. While this is well established for the HFD subunits, there remains some question over the potential role of NF-YA as either positive or negative regulators of this process. Here we provide strong support, in the form of genetic and biochemical analyses, that NF-YA, in complex with NF-YB/NF-YC proteins, can directly bind the distal CCAAT box in the FT promoter and are positive regulators of flowering in an FT-dependent manner.

Highlights

Plants undergo numerous developmental phase changes that are both species specific and intimately linked to the environments in which they evolved
Numerous labs have studied the molecular aspects of these timing mechanisms and discovered that many of these pathways converge on the gene FLOWERING LOCUS T (FT)
We focus on day length as an essential cue for flowering in the plant species Arabidopsis thaliana

Summary

Introduction

Plants undergo numerous developmental phase changes that are both species specific and intimately linked to the environments in which they evolved. A potent trigger of the transition to reproductive growth is photoperiod-dependent flowering. Photoperiod-dependent species use the relative length of day and night to either activate or repress flowering such that it is timed with the appropriate environmental conditions to maximize reproductive success. CO protein is stabilized in long days and is able to bind and transcriptionally activate FLOWERING LOCUS T (FT) [7, 8]. FT protein is the principal mobile hormone—or “florigen”—that travels from leaves, where the photoperiod signal is perceived, to the shoot apex, where the floral transition occurs [9,10,11,12]. FT activates its downstream targets, which includes APETALA 1 (AP1) and SUPPRESSOR OF CONSTANS 1 (SOC1) [13, 14]. Members of the heterotrimeric NUCLEAR FACTOR-Y (NF-Y) transcription factor family are required for activation of the FT promoter, initiating the downstream events leading to the floral transition [15,16,17,18,19,20]

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