FE, a phloem‐specific Myb‐related protein, promotes flowering through transcriptional activation of FLOWERING LOCUS T and FLOWERING LOCUS T INTERACTING PROTEIN 1

• Published in: The Plant journal : for cell and molecular biology 2015-09, Vol.83 (6), p.1059-1068
• Main Authors: Abe, Mitsutomo, Kaya, Hidetaka, Watanabe‐Taneda, Ayako, Shibuta, Mio, Yamaguchi, Ayako, Sakamoto, Tomoaki, Kurata, Tetsuya, Ausín, Israel, Araki, Takashi, Alonso‐Blanco, Carlos
• Format: Article
• Language: English
• Subjects: Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biosynthesis; Botany; florigen; flowering; FLOWERING LOCUS T; Flowers - genetics; Flowers - metabolism; Gene Expression Regulation, Plant; Kinases; long‐distance transport; Membrane Proteins - genetics; Membrane Proteins - metabolism; Mutation; Myb‐related protein; Phloem - genetics; Phloem - metabolism; Plant Leaves - genetics; Plant Leaves - metabolism; Plant Shoots - metabolism; Plants, Genetically Modified; Protein Transport; Proteins; Transcription Factors - genetics; Transcription Factors - metabolism
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.12951

Summary In many flowering plants, the transition to flowering is primarily affected by seasonal changes in day length (photoperiod). An inductive photoperiod promotes flowering via synthesis of a floral stimulus, called florigen. In Arabidopsis thaliana, the FLOWERING LOCUS T (FT) protein is an essential component of florigen, which is synthesized in leaf phloem companion cells and is transported through phloem tissue to the shoot apical meristem where floral morphogenesis is initiated. However, the molecular mechanism involved in the long‐distance transport of FT protein remains elusive. In this study, we characterized the classic Arabidopsis mutant fe, which is involved in the photoperiodic induction of flowering, and showed that FE encodes a phloem‐specific Myb‐related protein that was previously reported as ALTERED PHLOEM DEVELOPMENT. Phenotypic analyses of the fe mutant showed that FT expression is reduced in leaf phloem companion cells. In addition, the transport of FT protein from leaves to the shoot apex is impaired in the fe mutant. Expression analyses further demonstrated that FE is also required for transcriptional activation of FLOWERING LOCUS T INTERACTING PROTEIN 1 (FTIP1), an essential regulator for selective trafficking of the FT protein from companion cells to sieve elements. These findings indicate that FE plays a dual role in the photoperiodic induction of flowering: as a transcriptional activator of FT on the one hand, and its transport machinery component, FTIP1, on the other hand. Thus, FE is likely to play a role in regulating FT by coordinating FT synthesis and FT transport in phloem companion cells. Significance Statement FLOWERING LOCUS T (FT) is a component of the mobile floral stimulus florigen. Here we molecularly characterize the classic late‐flowering mutant fe and show that FE plays a regulatory role in coordinating FT synthesis and transport in phloem companion cells.