Cytokinin promotes flowering of Arabidopsis via transcriptional activation of the FT paralogue TSF (original) (raw)
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A Repressor Complex Governs the Integration of Flowering Signals in Arabidopsis
Developmental Cell, 2008
Multiple genetic pathways act in response to developmental cues and environmental signals to promote the floral transition, by regulating several floral pathway integrators. These include FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRES-SION OF CONSTANS 1 (SOC1). We show that the flowering repressor SHORT VEGETATIVE PHASE (SVP) is controlled by the autonomous, thermosensory, and gibberellin pathways, and directly represses SOC1 transcription in the shoot apex and leaf. Moreover, FT expression in the leaf is also modulated by SVP. SVP protein associates with the promoter regions of SOC1 and FT, where another potent repressor FLOWERING LOCUS C (FLC) binds. SVP consistently interacts with FLC in vivo during vegetative growth and their function is mutually dependent. Our findings suggest that SVP is another central regulator of the flowering regulatory network, and that the interaction between SVP and FLC mediated by various flowering genetic pathways governs the integration of flowering signals.
A Parade on Molecular Control of Flowering
International Journal of Environment, Agriculture and Biotechnology, 2016
Flower is a reproductive part of plant which contains complex array of functionally specialized structures.Photoperiodism, or the ability of an organism to detect day length, makes it possible for an event to occur at a particular time of year, thus allowing for a seasonal response. Circadian rhythms and photoperiodism have the common property of responding to cycles of light and darkness. Plant physiologists believed that the correlation between long days and flowering was a consequence of the accumulation of photosynthetic products synthesized during long days. Vernalization causes stable changes in the pattern of gene expression in the meristem, gene expression that are still stable even after vernalization is removed. The organ identity genes initially were identified through mutations that dramatically alter the structure and thus the identity of the floral organs produced in two adjacent whorls. The patterns of organ formation in the wild type and most of the mutant phenotypes are predicted and explained by ABC model of flower development. the transition to flowering involves a complex system of interacting factors that include among carbohydrates, gibberellins, cytokinins, bromeliads and ethylene.
Molecular Mechanisms of Hormone Functions in Flowering
Floriculture, Ornamental and Plant Biotechnology: Advances and Topical Issues Vol. I, 2006
Flowering in plants involves several sequential developmental programs from floral transition to floral organ development. In most species, the shoot apical meristems initially generate primordia that develop into vegetative organs, and are reprogrammed to give rise to floral primordia during the transition to flowering. These floral primordia can differentiate into flowers with different whorls of floral organs during flower development. Although striking progress has been made in understanding of flowering mechanisms in recent years, there are still many unanswered fundamental questions. The function of plant hormones (phytohormones) in flowering process is one of these puzzles. The phytohormones, including abscisic acid, auxin, cytokinin, ethylene, gibberellin acid (GA), brassinosteroid, and jasmonic acid, are small molecules affecting a wide range of developmental programs in plants. Some of these phytohormones, such as GA, show significant impact on the control of flowering time and floral organ development. In the last several years, molecular genetic studies in the genetically facile model plant Arabidopsis thaliana have provided significant insights into the molecular basis of various roles of phytohormones in plant development. Here we summarize the recent advances in our understanding of molecular mechanisms of hormone functions in flowering, with the emphasis on the GA, cytokinin, and auxin pathways.
Plant …, 2011
For plants to survive, it is essential for them to integrate signals from their external environment and respond to these signals. Flowering induction is one of the most important processes in the lives of seed plants. In Arabidopsis (Arabidopsis thaliana L.), induction of the flowering process is precisely regulated by four signaling pathways: the daylength (photoperiod) signal pathway, the autonomous pathway, the vernalization pathway, and the gibberellin pathway (Koornneef et al. 1998; Mouradov et al. 2002; Piñeiro and Coupland 1998; Simpson and Dean 2002). The signals from the pathways converge on the transcriptional regulation of floral morphogenesis integrator genes such as FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CO 1 that activate the transcription of genes necessary for flowering, such as APETALA1 and LEAFY (Moon et al. 2003; Piñeiro et al. 2003; Takada and Goto 2003). FT has been identified as the long-sought "florigen" that moves from leaves to the meristem and promotes flowering (
Different Roles of Flowering-Time Genes in the Activation of Floral Initiation Genes in Arabidopsis
The Plant Cell, 1997
We have analyzed double mutants that combine late-flowering mutations at four flowering-time loci (f E, FPA, F WA, and F T) with mutations at the LEAFY (L N) , APETALA7 (AP7), and TERMlNAL FLOWER7 (TFL7) loci involved in the floral initiation process (FLIP). Double mutants between ft-7 or fwa-7 and lfy-6 completely lack flowerlike structures, indicating that both F WA and F T act redundantly with LF Y to control AP7. Moreover, the phenotypes of ft-7 ap7-7 and fwa-7 ap7-7 double mutants are reminiscent of the phenotype of ap7-7 cal-7 double mutants, suggesting that FWA and F T could also be involved in the control of other FLlP genes. Such extreme phenotypes were not observed in double mutants between f v e d or fpa-7 and lfy-6 or ap7-7. Each of these showed a phenotype similar to that of ap7-7 or lfy-6 mutants grown under noninductive photoperiods, suggesting a redundant interaction with FLlP genes. Finally, the phenotype of double mutants combining the late-flowering mutations with tfH-2 were also consistent with the different roles of flowering-time genes.
Functional Plant Biology, 2005
The autonomous floral promotion pathway plays a key role in regulating the flowering time of the model dicot Arabidopsis thaliana (L.) Heynh. To investigate whether this pathway is present in monocots, two autonomous pathway components, FCA and FY, were isolated from rice (Oryza sativa L.) and ryegrass (Lolium perenne L.). The predicted FCA proteins (OsFCA and LpFCA) are highly conserved over the RNA-binding and WW protein interaction domains, and the FY proteins (OsFY and LpFY) possess highly conserved WD repeats but a less well conserved C-terminal region containing Pro–Pro–Leu–Pro (PPLP) motifs. In Arabidopsis, FCA limits its own production by promoting the polyadenylation of FCA pre-mRNA within intron 3 to form a truncated transcript called FCA-β. The identification of FCA-β transcripts in rice and ryegrass indicates that equivalent mechanisms occur in monocots. FCA’s autoregulation and flowering time functions require FCA to interact with the 3′ end-processing factor, FY. The F...
PLANT PHYSIOLOGY, 2012
The transition from vegetative to reproductive development is one of the most important phase changes in the plant life cycle. This step is controlled by various environmental signals that are integrated at the molecular level by so-called floral integrators. One such floral integrator in Arabidopsis (Arabidopsis thaliana) is the MADS domain transcription factor SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1). Despite extensive genetic studies, little is known about the transcriptional control of SOC1, and we are just starting to explore the network of genes under the direct control of SOC1 transcription factor complexes. Here, we show that several MADS domain proteins, including SOC1 heterodimers, are able to bind SOC1 regulatory sequences. Genome-wide target gene analysis by ChIP-seq confirmed the binding of SOC1 to its own locus and shows that it also binds to a plethora of flowering-time regulatory and floral homeotic genes. In turn, the encoded floral homeotic MADS domain proteins appear to bind SOC1 regulatory sequences. Subsequent in planta analyses revealed SOC1 repression by several floral homeotic MADS domain proteins, and we show that, mechanistically, this depends on the presence of the SOC1 protein. Together, our data show that SOC1 constitutes a major hub in the regulatory networks underlying floral timing and flower development and that these networks are composed of many positive and negative autoregulatory and feedback loops. The latter seems to be crucial for the generation of a robust flower-inducing signal, followed shortly after by repression of the SOC1 floral integrator.