Functional Divergence of the Arabidopsis Florigen-Interacting bZIP Transcription Factors FD and FDP

• Published in: Cell reports (Cambridge) Vol. 31; no. 9; p. 107717
• Main Authors: Romera-Branchat, Maida, Severing, Edouard, Pocard, Chloé, Ohr, Hyonhwa, Vincent, Coral, Née, Guillaume, Martinez-Gallegos, Rafael, Jang, Seonghoe, Andrés, Fernando, Madrigal, Pedro, Coupland, George
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 02.06.2020; Cell Press; Elsevier
• Subjects: ABA; Abscisic Acid - pharmacology; Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - classification; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Basic-Leucine Zipper Transcription Factors - classification; Basic-Leucine Zipper Transcription Factors - genetics; Basic-Leucine Zipper Transcription Factors - metabolism; bZIPs; CCAAT-Enhancer-Binding Protein-beta - genetics; CCAAT-Enhancer-Binding Protein-beta - metabolism; ChIP-seq; CRISPR-Cas Systems - genetics; FDP; florigen; Florigen - metabolism; flowering; Flowers - genetics; Flowers - metabolism; Gene Editing; Gene Expression Regulation, Plant - drug effects; Genotype; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Life Sciences; MADS Domain Proteins - genetics; MADS Domain Proteins - metabolism; Mutagenesis; Phylogeny; Plants, Genetically Modified - metabolism; RNA-seq; Transcription Factors - genetics; Transcription Factors - metabolism; ABA; FDP; RNA-seq; Arabidopsis; ChIP-seq; florigen; flowering; bZIPs; FD; FT
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2020.107717

Flowering of many plant species depends on interactions between basic leucine zipper (bZIP) transcription factors and systemically transported florigen proteins. Members of the genus Arabidopsis contain two of these bZIPs, FD and FDP, which we show have largely complementary expression patterns in shoot apices before and during flowering. CRISPR-Cas9-induced null mutants for FDP flower slightly earlier than wild-type, whereas fd mutants are late flowering. Identical G-box sequences are enriched at FD and FDP binding sites, but only FD binds to genes involved in flowering and only fd alters their transcription. However, both proteins bind to genes involved in responses to the phytohormone abscisic acid (ABA), which controls developmental and stress responses. Many of these genes are differentially expressed in both fd and fdp mutant seedlings, which also show reduced ABA sensitivity. Thus, florigen-interacting bZIPs have distinct functions in flowering dependent on their expression patterns and, at earlier stages in development, play common roles in phytohormone signaling. [Display omitted] •FDP is expressed at the shoot apex in a largely discrete pattern to FD•Flowering genes are bound only by FD, whereas other targets are bound by FD and FDP•FD and FDP bind to and regulate genes involved in ABA responses in seedlings•FT overexpressed in the phloem promotes flowering independently of FD and FDP Florigen activating complex facilitates the response to day length in higher plants and contains a specific class of bZIP transcription factor. Romera-Branchat et al. analyze the two factors of this class in Arabidopsis and find they play distinct functions in flowering control and participate in ABA signaling in early development.