The failure of seasonal adaptations can have a critical impact on an organism's survival and reproductive success. In people, one example of this is Seasonal Affective Disorder (SAD). Although the mechanisms of SAD remain elusive, its cause is seasonal variation in light conditions. In order to integrate information about seasonal change into their development, many organisms have evolved mechanisms to sense changes in day length. The long-term goal of our research program is to elucidate the molecular mechanisms of day- length measurement. Although the molecular mechanisms of photoperiodism have not yet been well described in many organisms, recent advances in the study of photoperiodic flowering in the model plant Arabidopsis have shed some light on them. In Arabidopsis, the core of photoperiodic time-measurement mechanisms is circadian regulated transcription of the floral activator CONSTANS (CO) gene, and light regulated CO protein stability and activity. In this proposal, we intend to further characterize these core molecular mechanisms by focusing on the functions of FKF1 E3 ubiquitin ligase through genetic, biochemical, and genomic approaches. The knowledge obtained in plant photoperiodism has often facilitated discoveries in other systems. Therefore, findings made in this proposal will be important not only for plant research, but also for broader understanding of photoperiodism in mammals and other systems. In addition, the findings may even provide some conceptional cues to understanding the mechanisms of SAD. Moreover, this type of transcriptional regulation is likely conserved in all eukaryotes, thus the findings will contribute to the understanding of a fundamental transcriptional regulation mechanism. In conclusion, elucidating the photoperiodic flowering mechanism is important not only for understanding a major plant reproduction mechanism, one that is directly applicable for an improvement of crop yield (an important contributor to human health, especially in developing countries) but also in understanding a sophisticated ubiquitination-dependent transcriptional mechanism that is universal among organisms.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Molecular Genetics B Study Section (MGB)
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Tompkins, Laurie
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University of Washington
Schools of Arts and Sciences
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Pudasaini, Ashutosh; Shim, Jae Sung; Song, Young Hun et al. (2017) Kinetics of the LOV domain of ZEITLUPE determine its circadian function in Arabidopsis. Elife 6:
Goralogia, Greg S; Liu, Tong-Kun; Zhao, Lin et al. (2017) CYCLING DOF FACTOR 1 represses transcription through the TOPLESS co-repressor to control photoperiodic flowering in Arabidopsis. Plant J 92:244-262
Shim, Jae Sung; Kubota, Akane; Imaizumi, Takato (2017) Circadian Clock and Photoperiodic Flowering in Arabidopsis: CONSTANS Is a Hub for Signal Integration. Plant Physiol 173:5-15
Fenske, Myles P; Imaizumi, Takato (2016) Circadian Rhythms in Floral Scent Emission. Front Plant Sci 7:462
Kinmonth-Schultz, Hannah A; Tong, Xinran; Lee, Jae et al. (2016) Cool night-time temperatures induce the expression of CONSTANS and FLOWERING LOCUS T to regulate flowering inĀ Arabidopsis. New Phytol 211:208-24
Li, Shibai; Wang, Xiaochen; He, Shan et al. (2016) CFLAP1 and CFLAP2 Are Two bHLH Transcription Factors Participating in Synergistic Regulation of AtCFL1-Mediated Cuticle Development in Arabidopsis. PLoS Genet 12:e1005744
Golembeski, Greg S; Imaizumi, Takato (2015) Photoperiodic Regulation of Florigen Function in Arabidopsis thaliana. Arabidopsis Book 13:e0178
Fenske, Myles P; Hewett Hazelton, Kristen D; Hempton, Andrew K et al. (2015) Circadian clock gene LATE ELONGATED HYPOCOTYL directly regulates the timing of floral scent emission in Petunia. Proc Natl Acad Sci U S A 112:9775-80
Song, Young Hun; Shim, Jae Sung; Kinmonth-Schultz, Hannah A et al. (2015) Photoperiodic flowering: time measurement mechanisms in leaves. Annu Rev Plant Biol 66:441-64
Kubota, Akane; Shim, Jae Sung; Imaizumi, Takato (2015) Natural variation in transcriptional rhythms modulates photoperiodic responses. Trends Plant Sci 20:259-61

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