Floral responses to photoperiod are correlated with the timing of rhythmic expression relative to dawn and dusk in<i>Arabidopsis</i>

Roden, Laura C.; Song, Hae-Ryong; Jackson, Stephen D.; Morris, Karl; Carré, Isabelle A.

doi:10.1073/pnas.192365599

Cited by 109 publications

(81 citation statements)

References 32 publications

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“…When the day-night cycle is shortened to 21 h and thus matched to the endogenous period in toc1 mutants, the CO pattern no longer differs from that in wild type and the short-day early flowering phenotype of toc1 is suppressed (Strayer et al 2000;Yanovsky and Kay 2002). Additional, more sophisticated manipulations of length and structure of the light/dark cycle, similar to what had been used in the early days of studying the circadian clock (Nanda and Hamner 1958;Pittendrigh 1960), confirmed that bringing peak levels of CO mRNA into the light phase promotes flowering of wild-type plants under short photoperiods (Roden et al 2002).…”

Section: Molecular Basis Of the External Coincidence Modelmentioning

confidence: 75%

Move on up, it’s time for change—mobile signals controlling photoperiod-dependent flowering

Kobayashi

Weigel²

2007

Genes Dev.

401

348

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Plants do not bloom randomly-but how do they know when and where to make flowers? Here, we review molecular mechanisms that integrate spatial and temporal information in day-length-dependent flowering. Primarily through genetic analyses in two species, Arabidopsis thaliana and rice, we today understand the essentials of two central issues in plant biology: how the appropriate photoperiod generates an inductive stimulus based on an external coincidence mechanism, and the nature of the mobile flowering signal, florigen, which relays photoperiod-dependent information from the leaf to the growing tip of the plant, the shoot apex.We all love springtime, not least because flowers are everywhere. But how do plants know it is the right time to bloom? Just like us, plants can recognize the seasons. Among different indicators such as temperature and light, the increase in day length is the most robust telltale sign that spring is upon us, at least for those of us who do not live in the tropics. The ability to recognize and respond to changes in day length is known as photoperiodism and is common to both plants and animals. In this review, we will focus on events downstream from the circadian clock that relay the photoperiodic signal from the site of perception, the leaves, to the shoot apex, where flowers are formed. Recent advances in this area have finally provided a molecular underpinning for two long-standing tenets of plant biology, the external coincidence model and the florigen hypothesis. The discovery of photoperiodic control of floweringOne of the first to recognize the importance of day length in flowering was the English botanist Arthur Henfrey (1852), who suggested that summer day length, which changes with latitude, is an important factor in determining where plants could grow. Some 50 years later, the French scientist Tournois (1912) found that both Humulus (hop) and Cannabis (hemp) flower precociously when kept in winter in a greenhouse supplemented with artificial light, in agreement with Henfrey's postulate. The German Klebs made similar observations with Sempervivum (house leek). Importantly, he realized that it was unlikely to be light quantity (as a nutritive factor, as he called it) but rather light duration (acting as a catalytic factor) that was critical in this process (summarized in Klebs 1913).Despite Tournois' and Klebs' contributions, the discovery of day length as a crucial factor in flowering control is generally accredited to Wightman Garner and Harry Allard, scientists at the US Department of Agriculture. Allard (1920, 1923) were working on two practical problems. One was the question of why certain strains of soybeans often would initiate flowers more or less simultaneously, typically during the height of summer, even if farmers had spread out the sowing dates. The other related to a tobacco variety that had spontaneously arisen in the field. This strain, appropriately called "Maryland Mammoth," would grow very tall, yielding nearly 100 leaves, whereas normal tobacco plants switch to ma...

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Section: Molecular Basis Of the External Coincidence Modelmentioning

confidence: 75%

Move on up, it’s time for change—mobile signals controlling photoperiod-dependent flowering

Kobayashi

Weigel²

2007

Genes Dev.

401

348

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“…The double mutant is almost day neutral and has an early phase of circadian gene expression during day-night cycles (Mizoguchi et al 2002). It has been proposed that this circadian phenotype affects the phase of CO expression during short days, thereby leading to early flowering (Mizoguchi et al 2002;Roden et al 2002;Yanovsky and Kay 2002). Interestingly, the circadian and flowering-time phenotypes of srr1 mutants are very similar to those of cca1, lhy, and toc1 loss-of-function alleles, clearly suggesting a role for SRR1 in the clock (Figs.…”

Section: Srr1 Is Required For Normal Circadian Oscillator Functionmentioning

confidence: 99%

TheArabidopsis SRR1gene mediates phyB signaling and is required for normal circadian clock function

Staiger

Allenbach²,

Salathia³

et al. 2003

Genes Dev.

105

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Plants possess several photoreceptors to sense the light environment. In Arabidopsis cryptochromes and phytochromes play roles in photomorphogenesis and in the light input pathways that synchronize the circadian clock with the external world. We have identified SRR1 (sensitivity to red light reduced), a gene that plays an important role in phytochrome B (phyB)-mediated light signaling. The recessive srr1 null allele and phyB mutants display a number of similar phenotypes indicating that SRR1 is required for normal phyB signaling. Genetic analysis suggests that SRR1 works both in the phyB pathway but also independently of phyB. srr1 mutants are affected in multiple outputs of the circadian clock in continuous light conditions, including leaf movement and expression of the clock components, CCA1 and TOC1. Clock-regulated gene expression is also impaired during day-night cycles and in constant darkness. The circadian phenotypes of srr1 mutants in all three conditions suggest that SRR1 activity is required for normal oscillator function. The SRR1 gene was identified and shown to code for a protein conserved in numerous eukaryotes including mammals and flies, implicating a conserved role for this protein in both the animal and plant kingdoms.

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“…In the flowering plant Arabidopsis thaliana, the circadian clock phases the peak mRNA abundance of many genes to distinct times of day (3). Furthermore, the phase angle of specific circadian rhythms with the environmental light-dark (LD) cycle controls seasonal behavior such as flowering (4)(5)(6).…”

mentioning

confidence: 99%

Two Arabidopsis circadian oscillators can be distinguished by differential temperature sensitivity

Michael

Salomé

McClung

2003

Proc. Natl. Acad. Sci. U.S.A.

136

138

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Circadian rhythms are widespread in nature and reflect the activity of an endogenous biological clock. In metazoans, the circadian system includes a central circadian clock in the brain as well as distinct clocks in peripheral tissues such as the retina or liver. Similarly, plants have distinct clocks in different cell layers and tissues. Here, we show that two different circadian clocks, distinguishable by their sensitivity to environmental temperature signals, regulate the transcription of genes that are expressed in the Arabidopsis thaliana cotyledon. One oscillator, which regulates CAB2 expression, responds preferentially to light-dark versus temperature cycles and fails to respond to the temperature step associated with release from stratification. The second oscillator, which regulates CAT3 expression, responds preferentially to temperature versus light-dark cycles and entrains to the release from stratification. Finally, the phase response curves of these two oscillators to cold pulses are distinct. The phase response curve of the oscillator component TOC1 to cold pulses is similar to that of CAB2, indicating that CAB2 is regulated by a TOC1-containing clock. The existence of two clocks, distinguishable on the basis of their sensitivity to temperature, provides an additional means by which plants may integrate both photoperiodic and temperature signals to respond to the changing seasons. T he circadian clock is an endogenous oscillator with an approximate period of 24 hr that can be synchronized, or entrained, to the exact period of daily oscillations in light and temperature (1). This enables an organism to phase its biological activities to the correct time of day. The sleep-wake cycle in humans, activity and eclosion rhythms in flies, and conidiation in Neurospora are rhythmic processes that display distinct phase angles with the environment (2). In the flowering plant Arabidopsis thaliana, the circadian clock phases the peak mRNA abundance of many genes to distinct times of day (3). Furthermore, the phase angle of specific circadian rhythms with the environmental light-dark (LD) cycle controls seasonal behavior such as flowering (4-6).The clock is temperature-compensated, meaning that the pace of the clock is more or less constant across a range of temperatures and fails to exhibit the acceleration with temperature that characterizes typical enzymatic reactions. Nonetheless, temperature serves as an important environmental time cue and entrainment to temperature cycles has been demonstrated in a number of systems (7,8). It is commonly assumed that light is the dominant environmental time cue for circadian clocks, although few studies have systematically compared light and temperature (9-12). In fact, temperature cycles applied antiphase to LD cycles set the phase angle of multiple rhythms, including CO 2 assimilation in Kalanchoë (13), ethylene production in sorghum (14), and conidiation in Neurospora (15).We compared the relative strengths of temperature cycles and LD cycles as determinants of the ph...

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Floral responses to photoperiod are correlated with the timing of rhythmic expression relative to dawn and dusk inArabidopsis

Cited by 109 publications

References 32 publications

Move on up, it’s time for change—mobile signals controlling photoperiod-dependent flowering

Move on up, it’s time for change—mobile signals controlling photoperiod-dependent flowering

TheArabidopsis SRR1gene mediates phyB signaling and is required for normal circadian clock function

Two Arabidopsis circadian oscillators can be distinguished by differential temperature sensitivity

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