ZEITLUPE and FKF1: novel connections between flowering time and circadian clock control

B-box (BBX) zinc finger proteins play critical roles in both vegetative and reproductive development in plants. Many BBX proteins have been identified in Arabidopsis thaliana as floral transition regulatory factors, such as CO, BBX7 (COL9), BBX19, and BBX32. BBX32 is involved in flowering time control through repression of COL3 in Arabidopsis thaliana, but it is still elusive that whether and how BBX32 directly interacts with flowering signal integrators of AGAMOUS-LIKE 24 (AGL24) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) in Chinese cabbage (Brassica rapa L. ssp. pekinensis) or other plants. In this study, B-box-32(BBX32), a transcription factor in this family with one B-box motif was cloned from B. rapa, acted as a circadian clock protein, showing expression changes during the circadian period. Additional experiments using GST pull-down and yeast two-hybrid assays indicated that BrBBX32 interacts with BrAGL24 and does not interact with BrSOC1, while BrAGL24 does interact with BrSOC1. To investigate the domains involved in these protein-protein interactions, we tested three regions of BrBBX32. Only the N-terminus interacted with BrAGL24, indicating that the B-box domain may be the key region for protein interaction. Based on these data, we propose that BrBBX32 may act in the circadian clock pathway and relate to the mechanism of flowering time regulation by binding to BrAGL24 through the B-box domain. This study will provide valuable information for unraveling the molecular regulatory mechanisms of BrBBX32 in flowering time of B. rapa.

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The F-Box Protein ZEITLUPE Confers Dosage-Dependent Control on the Circadian Clock, Photomorphogenesis, and Flowering Time

The Plant Cell ◽

10.1105/tpc.016808 ◽

2004 ◽

Vol 16 (3) ◽

pp. 769-782 ◽

Cited By ~ 136

Author(s):

David E. Somers ◽

Woe-Yeon Kim ◽

Ruishuang Geng

Keyword(s):

Circadian Clock ◽

Flowering Time ◽

F Box Protein

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Initial embedding of TRANSPARENT TESTA GLABRA 1 in the Arabidopsis thaliana flowering time regulatory pathway

10.7287/peerj.preprints.27974v1 ◽

2019 ◽

Author(s):

Barbara A M Paffendorf ◽

Rawan Qassrawi ◽

Andrea M Meys ◽

Laura Trimborn ◽

Andrea Schrader

Keyword(s):

Arabidopsis Thaliana ◽

Circadian Clock ◽

Flowering Time ◽

Response Regulator ◽

Regulatory Pathway ◽

In Planta ◽

Transcript Levels ◽

Transparent Testa ◽

Flowering Locus

Pleiotropic regulatory factors mediate concerted responses of the plant’s trait network to endogenous and exogenous cues. TRANSPARENT TESTA GLABRA 1 (TTG1) is a pleiotropic regulator that has been predominantly described in its role as a regulator of early accessible developmental traits. Although its closest homologs LIGHT-REGULATED WD1 (LWD1) and LWD2 are regulators of photoperiodic flowering, a role of TTG1 in flowering time regulation has not been reported. Here we reveal that TTG1 is a regulator of flowering time in Arabidopsis thaliana and changes transcription levels of different targets within the flowering time regulatory pathway. TTG1 mutants flower early and TTG1 overexpression lines flower late at long-day conditions. Consistently, TTG1 can suppress the transcript levels of the floral integrators FLOWERING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CO1 and can act as an activator of circadian clock components. Moreover, TTG1 might form feedback loops at the protein level. The TTG1 protein interacts with PSEUDO RESPONSE REGULATOR (PRR)s and basic HELIX-LOOP-HELIX 92 (bHLH92) in yeast. In planta, the respective pairs exhibit interesting patterns of localization including a recruitment of TTG1 by PRR5 to subnuclear foci. This mechanism proposes additional layers of regulation by TTG1 and might aid to specify the function of bHLH92. Within another branch of the pathway, TTG1 can elevate FLOWERING LOCUS C (FLC) transcript levels. FLC mediates signals from the vernalization, ambient temperature and autonomous pathway and the circadian clock is pivotal for the plant to synchronize with diurnal cycles of environmental stimuli like light and temperature. Our results suggest an unexpected positioning of TTG1 upstream of FLC and upstream of the circadian clock. In this light, this points to an adaptive value of the role of TTG1 in respect to flowering time regulation.

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A putative flowering-time-related Dof transcription factor gene, JcDof3, is controlled by the circadian clock in Jatropha curcas

Plant Science ◽

10.1016/j.plantsci.2011.05.003 ◽

2011 ◽

Vol 181 (6) ◽

pp. 667-674 ◽

Cited By ~ 26

Author(s):

Jing Yang ◽

Ming-Feng Yang ◽

Wen-Peng Zhang ◽

Fan Chen ◽

Shi-Hua Shen

Keyword(s):

Transcription Factor ◽

Circadian Clock ◽

Flowering Time ◽

Jatropha Curcas ◽

Transcription Factor Gene ◽

Factor Gene ◽

Dof Transcription Factor

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Genetic Linkages of the Circadian Clock-Associated Genes, TOC1, CCA1 and LHY, in the Photoperiodic Control of Flowering Time in Arabidopsis thaliana

Plant and Cell Physiology ◽

10.1093/pcp/pcm067 ◽

2007 ◽

Vol 48 (7) ◽

pp. 925-937 ◽

Cited By ~ 67

Author(s):

Yusuke Niwa ◽

Shogo Ito ◽

Norihito Nakamichi ◽

Tsuyoshi Mizoguchi ◽

Kanae Niinuma ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Circadian Clock ◽

Flowering Time ◽

Photoperiodic Control ◽

Genetic Linkages

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Field microenvironments regulate crop diel transcript and metabolite rhythms

10.1101/2021.04.08.439063 ◽

2021 ◽

Author(s):

Luiza L. B. Dantas ◽

Maira M. Dourado ◽

Natalia O. de Lima ◽

Natale Cavacana ◽

Milton Y. Nishiyama-Jr. ◽

...

Keyword(s):

Circadian Clock ◽

Flowering Time ◽

Clock Gene ◽

High Density ◽

Natural Conditions ◽

The West ◽

Circadian Clock Gene ◽

West Side ◽

Agronomical Traits ◽

Stalk Weight

Most research in plant chronobiology was done in laboratory conditions. However, they usually fail to mimic natural conditions and their nuanced fluctuations, highlighting or obfuscating rhythmicity. High-density crops, such as sugarcane (Saccharum hybrid), generate field microenvironments that have specific light and temperature, as they shade each other. Here, we measured the metabolic and transcriptional rhythms in the leaves of 4-month-old (4 mo.) and 9 mo. sugarcane grown in the field. Most of the assayed rhythms in 9 mo. sugarcane peaked >1 h later than in 4 mo. sugarcane, including rhythms of the circadian clock gene, LATE ELONGATED HYPOCOTYL (LHY), but not TIMING OF CAB EXPRESSION (TOC1). We hypothesized that older sugarcane perceives dawn later than younger sugarcane, due to self-shading. As a test, we measured LHY rhythms in plants on the east and the west side of a field. We also tested if a wooden wall built between lines of sugarcane also changed their rhythms. In both experiments, the LHY peak was delayed in the plants shaded at dawn. We conclude that plants in the same field may have different phases due to field microenvironments, which may impact important agronomical traits, such as flowering time, stalk weight and number.

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TRANSPARENT TESTA GLABRA 1 participates in flowering time regulation in Arabidopsis thaliana

PeerJ ◽

10.7717/peerj.8303 ◽

2020 ◽

Vol 8 ◽

pp. e8303 ◽

Cited By ~ 1

Author(s):

Barbara A.M. Paffendorf ◽

Rawan Qassrawi ◽

Andrea M. Meys ◽

Laura Trimborn ◽

Andrea Schrader

Keyword(s):

Arabidopsis Thaliana ◽

Circadian Clock ◽

Flowering Time ◽

Response Regulator ◽

In Planta ◽

Transcript Levels ◽

Autonomous Pathway ◽

Transparent Testa ◽

Flowering Locus

Pleiotropic regulatory factors mediate concerted responses of the plant’s trait network to endogenous and exogenous cues. TRANSPARENT TESTA GLABRA 1 (TTG1) is such a factor that has been predominantly described as a regulator of early developmental traits. Although its closest homologs LIGHT-REGULATED WD1 (LWD1) and LWD2 affect photoperiodic flowering, a role of TTG1 in flowering time regulation has not been reported. Here we reveal that TTG1 is a regulator of flowering time in Arabidopsis thaliana and changes transcript levels of different targets within the flowering time regulatory pathway. TTG1 mutants flower early and TTG1 overexpression lines flower late at long-day conditions. Consistently, TTG1 can suppress the transcript levels of the floral integrators FLOWERING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CO1 and can act as an activator of circadian clock components. Moreover, TTG1 might form feedback loops at the protein level. The TTG1 protein interacts with PSEUDO RESPONSE REGULATOR (PRR)s and basic HELIX-LOOP-HELIX 92 (bHLH92) in yeast. In planta, the respective pairs exhibit interesting patterns of localization including a recruitment of TTG1 by PRR5 to subnuclear foci. This mechanism proposes additional layers of regulation by TTG1 and might aid to specify the function of bHLH92. Within another branch of the pathway, TTG1 can elevate FLOWERING LOCUS C (FLC) transcript levels. FLC mediates signals from the vernalization, ambient temperature and autonomous pathway and the circadian clock is pivotal for the plant to synchronize with diurnal cycles of environmental stimuli like light and temperature. Our results suggest an unexpected positioning of TTG1 upstream of FLC and upstream of the circadian clock. In this light, this points to an adaptive value of the role of TTG1 in respect to flowering time regulation.

Download Full-text