Studies on the Nature of the Endogenous Rhythm Affecting Photoperiodic Response of Biloxi Soybean

Nanda, K. K.; Hamner, K. C.

doi:10.1086/335992

Cited by 165 publications

(83 citation statements)

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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: 99%

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

Kobayashi

Weigel²

2007

Genes Dev.

410

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: 99%

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

Kobayashi

Weigel²

2007

Genes Dev.

410

348

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“…Small differences in the duration of the light period might have large effects on flowering time and explain the accelerated flowering observed under 28-hr T cycles. To test whether the absolute duration of light within a cycle determines the floral response, we applied a variant of the T cycle protocol, first used by Nanda and Hamner (26). NH cycles consist of constant photoperiods (8 hr in this case) alternating with dark periods of variable length.…”

Section: Effects Of Varying the Total Duration Of The Light͞dark Cyclementioning

confidence: 99%

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

Roden

Song

Jackson

et al. 2002

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

109

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Daylength, or photoperiod, is perceived as a seasonal signal for the control of flowering of many plants. The measurement of daylength is thought to be mediated through the interaction of phototransduction pathways with a circadian rhythm, so that flowering is induced (in long-day plants) or repressed (in short-day plants) when light coincides with a sensitive phase of the circadian cycle. To test this hypothesis in the facultative long-day plant, Arabidopsis thaliana, we used varying, non-24-hr light͞dark cycles to alter the timing of circadian rhythms of gene expression relative to dawn and dusk. Effects on circadian rhythms were correlated with those on flowering times. We show that conditions that displaced subjective night events, such as expression of the flowering time regulator CONSTANS into the light portion of the cycle, were perceived as longer days. This work demonstrates that the perception of daylength in Arabidopsis relies on adjustments of the phase angle of circadian rhythms relative to the light͞dark cycle, rather than on the measurement of the absolute duration of light and darkness.T he sexual reproduction of many plants and animals occurs on a seasonal basis and is triggered by changes in daylength, or photoperiod. In plants, floral responses to photoperiod vary widely between species and have been classified into three broad categories. Short-day plants are induced to flower when the photoperiod is shorter than a critical daylength, whereas longday plants flower under photoperiods that are longer than their critical daylength; day-neutral plants are insensitive to photoperiod.Measurement of day-or night-length could, in theory, be performed by an hourglass-type of timer, measuring time from either dawn or dusk, or even the relative amounts of light and darkness. For example, flowering of cocklebur (Xanthium) is essentially determined by the absolute duration of darkness (1, 2), and induction of diapause in the aphid Megoura viciae relies on measuring time from dusk (3). However, the total duration of light or darkness was not the critical factor determining the response in other plant and animal species. For example, when Japanese morning glory (Ipomea nil, also described as Pharbitis nil) were transferred to extended nights, appropriately timed night breaks mimicked the effects of long days and inhibited flowering (4). Remarkably, sensitivity to night breaks varied with a 24-hr period. Gonadal development in birds and induction of diapause in insects also exhibited rhythmic responsiveness to short light signals in constant darkness (3, 5).These and other similar findings (reviewed in ref.2) suggested that photoperiodic time measurement may involve a circadian rhythm of responsiveness to light, known as the photoperiodic response rhythm (6). Two possible mechanisms have been proposed, by which a circadian clock might mediate perception of photoperiod (7). According to the external coincidence model, a photoperiodic response may be induced when an external signal (light) coincides with a pho...

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“…Second, this proposition is reinforced because many organisms exhibit a rhythmic photoperiodic response to a class of experiments using short days and long nights where the latter vary in duration among separate experiments ( Figure 2). This experiment is known as the Nanda-Hamner protocol (hereafter, NH) after the first biologists to use it (Nanda and Hamner, 1958). A positive or rhythmic response to NH has been interpreted both historically (Pittendrigh, 1981;Saunders, 1982) and more recently (Tauber and Kyriacou, 2001;Goldman et al, 2004;Saunders, 2010a) as an overt expression of the circadian clock.…”

Section: Introductionmentioning

confidence: 99%

Genetic correlations and the evolution of photoperiodic time measurement within a local population of the pitcher-plant mosquito, Wyeomyia smithii

2011

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The genetic relationship between the daily circadian clock and the seasonal photoperiodic timer remains a subject of intense controversy. In Wyeomyia smithii, the critical photoperiod (an overt expression of the photoperiodic timer) evolves independently of the rhythmic response to the Nanda-Hamner protocol (an overt expression of the daily circadian clock) over a wide geographical range in North America. Herein, we focus on these two processes within a single local population in which there is a negative genetic correlation between them. We show that antagonistic selection against this genetic correlation rapidly breaks it down and, in fact, reverses its sign, showing that the genetic correlation is due primarily to linkage and not to pleiotropy. This rapid reversal of the genetic correlation within a small, single population means that it is difficult to argue that circadian rhythmicity forms the necessary, causal basis for the adaptive divergence of photoperiodic time measurement within populations or for the evolution of photoperiodic time measurement among populations over a broad geographical gradient of seasonal selection. Heredity (2012) 108, 473-479; doi:10.1038/hdy.2011.108; published online 9 November 2011Keywords: linkage; pleiotropy; photoperiodism; circadian rhythmicity; antagonistic selection INTRODUCTION Herein we are concerned with the genetic and evolutionary relationship between the photoperiodic timer that serves to organize seasonal events and the circadian clock that serves to organize daily events in the life histories of animals. 'Only model organisms live in a world of endless summer; most organisms in nature confront a seasonal environment. Fitness in a seasonal environment involves the abilities to exploit the favorable season, to avoid or mitigate the effects of the unfavorable season, and to make a timely transition between the two lifestyles' (Bradshaw et al., 2004). Timing is of the essence. Organisms cannot wait for the onset of winter but must have physiological mechanisms that enable them to prepare for the winter in advance. A wide variety of animals from rotifers to rodents use the length of the day (photoperiod) as an anticipatory cue in preparation for the changing seasons. Examples include the use of day length to cue the seasonal timing of migration in birds, to cue the seasonal timing of reproduction in mammals, and to cue the seasonal timing of diapause (dormancy) in arthropods (Bradshaw and Holzapfel, 2007a). Photoperiodic response is typically determined by exposing animals to a range of day lengths and plotting percent response as a function of hours of light per day to which they were exposed (Figure 1a). Photoperiodic response curves are usually sigmoid in shape and the day length that promotes a response in 50% of a sample population defines the critical photoperiod (hereafter, CPP) that is used as a proxy for the photoperiodic response curve.For more than 75 years, it has been hypothesized that the causal basis of the seasonal photoperiodic timer is controlled by ...

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Studies on the Nature of the Endogenous Rhythm Affecting Photoperiodic Response of Biloxi Soybean

Cited by 165 publications

References 0 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

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

Genetic correlations and the evolution of photoperiodic time measurement within a local population of the pitcher-plant mosquito, Wyeomyia smithii

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