Photoperiodic control of flowering time: a review

Abstract

The rotation of the earth results in periodic changes in environmental factors such as daylength and temperature; the circadian clock is the endogenous mechanism responsible for day-length measurement, and allows plants to anticipate these fluctuations and modulate their developmental programs to maximize adaptation to those environmental cues. Flowering represents the transition from a vegetative to reproductive phase and is controlled by complex and highly regulated genetic pathways. In many plants, the time of flowering is strongly influenced by photoperiod, which synchronizes the floral transition with the favourable season of the year. Over the last decade, genetic approaches have aided the discovery of many signalling components involved in the photoperiod pathway and here, we highlight the significant progress made in identifying the molecular mechanisms that measure daylength and control flowering initiation in Arabidopsis, a long day (LD) plant, and in rice, a short day (SD) plant. Some components of the Arabidopsis regulatory network are conserved in other species, but the difference in the function of particular genes may contribute to the opposite photoperiodic flowering response observed between LD and SD plants. The specific regulatory mechanisms involved in controlling CONSTANS (CO) expression and stability by the circadian clock and the different photoreceptors will be described. In addition, the role of FLOWERING LOCUS T (FT), as part of the florigen, and several other light signalling and circadian-dependent components in photoperiodic flowering will be also discussed.Additional key words: circadian clock, CONSTANS, florigen, FT, photoperiodism, photoreceptors. Resumen Revisión. Control fotoperiódico del tiempo de floraciónLa rotación diaria de la tierra provoca cambios periódicos en la duración del día o en la temperatura, y el reloj circadiano es un mecanismo endógeno responsable de la medida de la duración del día; este oscilador molecular permite a los organismos anticiparse a dichos cambios y adaptar su desarrollo de manera adecuada. La floración representa la transición desde una fase vegetativa del crecimiento a una reproductiva, y está controlada por diferentes rutas, muy complejas y altamente reguladas. En muchas plantas, esta transición está controlada principalmente por la duración del día o fotoperiodo, el cual sincroniza la floración con la estación más favorable del año. En la última década, diferentes estudios genéticos han facilitado la caracterización de muchos componentes de señalización involucrados en la ruta del fotoperiodo y en esta revisión se discute el progreso reciente que se ha llevado a cabo en la identificación de los mecanismos moleculares que permiten medir la duración del día, y que controlan el tiempo de floración en Arabidopsis, una especie de día largo, y en arroz, un especie de día corto. Aunque los componentes de las rutas reguladoras de Arabidopsis parecen conservarse en otras especies, la diferencia de función de genes concretos parece contribuir a...

Differential floral development and gene expression in grapevines during long and short photoperiods suggests a role for floral genes in dormancy transitioning

“…GI, which promotes CO, also promotes LATE ELONGATED HYPOCOTYL (LHY) upregulation of TOC1 in a ''three-loop model of the circadian clock'' in A. thaliana (Lagercrantz 2009), where LHY in turn suppresses GI and promotes PRR7 and PRR9. PRR7 and PRR9 have been shown to suppress LHY (Lagercrantz 2009) and have been reported to upregulate CO through suppression of CDF1, a repressor of CO (Jarillo et al 2008). COL-2 could also be upregulated in a similar fashion (Fig.…”

Effects of Photoperiodism to The Growth Rate of Hibiscus sabdariffa L

“…Photoperiod controls not only flowering [17] but also seed germination, stem and leaf growth, assimilate portioning and secondary metabolism [3]. And in this study photoperiod influenced height plant, diameter of stem, number and color of roselle leaves.…”

Molecular Regulation of Flowering Time in Grasses

“…This is despite the high similarity between the PHYA locus in Arabidopsis rice, sorghum and maize [62] suggesting that a similar response would be expected. However, PHYA mutations in combination with PHYB or PHYC cause early flowering in rice [61]. In addition, studies have shown that PHYC plays an essential role in the acceleration of wheat flowering under LD photoperiods.…”

“…Plants use many photoreceptors to detect the intensity and quality of light, including PHYTOCHROMES (PHY), which absorb the red and far-red region of the visible spectrum, and the CRYPTOCHROMES (CRY) [63]. Arabidopsis contains five PHYs (A-E), where accumulation of CO in LD is due to stabilization mediated by phytochrome A (PHYA), cryptochromes (CRY1/2) and SUPPRESSOR OF PHYA-105 (SPA1) [61]. However, it has been shown that PHYB signals delay flowering by destabilizing CO protein during the morning and have an inhibitory effect on FT expression [60].…”

“…The plant circadian system consists of biochemical timing mechanisms that temporarily modulate the function of several signalling pathways to measures changes in day-length and promote suitable timing of flowering to maximize reproductive success [2,3,6,7,9,10,[13][14][15]21,24,26,28,29,31,36,38,41,42,46,48,49,[56][57][58][59][60][61][62][63][64][65][66]. The photoperiod response on flowering time varies among grasses.…”