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Summary
• Arabidopsis FT protein is a component of florigen, a systemic signal that has been demonstrated to control photoperiodic flowering in diverse plant species. • FT is synthesized in the leaves and selectively transported to the SAM. In the SAM cells, FT binds 14-3-3 and FD to form a ternary ‘florigen activation complex’, which activates FMI genes. • Photoperiodic regulation of floral initiation is also regulated by a systemic floral inhibitor or antiflorigen, which is exported from the non-induced leaves. The antiflorigen production system prevents precocious flowering.
Florigens and antiflorigens: a molecular genetic understanding
Reporter：sang na 8/12/2015
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OUTLINE
Introduction
Main content Summary
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Introduction ——the florigen mystery
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Main content —— Floral signal transduction
• The actions of all flowering time pathways ultimately converge to control the expression of a small number of so-called floral pathway integrators (FPIs), which include FT, TSF, SUPPRESSOR OF CONSTANS 1 (SOC1) and AGAMOUSLIKE 24 (AGL24). These act on the floral meristem identity (FMI) genes, LEAFY (LFY), FRUITFUL (FUL) and APETALA1(AP1), resulting in the initiation of flowering.
• Over the years, a number of studies have led to the development of three models to explain the photoperiodic regulation of floral induction. a) The first model is that of a flowering hormone-like substance, or florigen, which was first postulated by Mikhail. b) The second model was known as the nutrient diversion hypothesis. c) The third model is that of the multifactorial control hypothesis, which was proposed by Georges
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Introduction ——the florigen mystery
•A vast body of literature suggests that FLOWERING LOCUS T (FT) protein and its paralogue TWIN SISTER OF FT (TSF) act as florigen, or at least that they represent part of it in a range of different plant species. •However, this chapter will highlight the literature that has increased our understanding of several aspects of florigenic and antiflorigenic signalling in plants.
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The photoperiodic pathway: a model for the mode of action of FT
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Main content —— Florigen: beyond floral signal transduction
• Recent studies have led to the identification of members of the FT gene family as a major component of the tuber-inducing signal tuberigen. • Interestingly, and perhaps understandably, the discovery of pleiotropic effects of FT genes has emerged as a field of research with significant potential to enhance several aspects of crop performance and quality.
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