Light and flowering regulators convene in nuclear photobodies

Flowering is controlled by multiple environmental stimuli. A new signal-integrating component of light and photoperiodic signalling is recruited to nuclear photobodies to regulate the transcriptional activation of flowering time in Arabidopsis thaliana.

HFSP Long-Term Fellow Eirini Kaiserli and colleagues
authored on Fri, 27 November 2015

Light is a fundamental informational signal that regulates plant development, adaptation and survival. Photomorphogenesis and flowering, two of the most dramatic developmental transitions during the life-cycle of a plant, are triggered by an ensemble of environmental stimuli and signalling networks. Here, we uncover the molecular function of TZP1 (TANDEM ZINC-FINGER PLUS3), a natural variant that acts as a transcriptional regulator integrating light and photoperiodic signalling in nuclear microdomains. Our findings show that TZP is localised to nuclear photobodies to induce the expression of the floral inducer genes, FLOWERING LOCUS T (FT) and CONSTANS (CO) via a direct interaction with the red light receptor phytochrome B (phyB). PhyB is essential for recruiting TZP to nuclear photobodies and to chromatin regions on the promoters of FT and CO.      


Figure: Confocal image analysis of a TZP tagged with a fluorescent marker. TZP compartmentalisation in nuclear photobodies that contain key signalling components correlates with the induction of FT gene expression that leads to flowering initiation.                                                                                             

In addition to identifying TZP as a new signal-integrating component of photoperiodic flowering, we signify a transcriptional regulatory role to the enigmatic plant nuclear photobodies. We hope that our findings will open new avenues to understanding the molecular function of nuclear bodies as transcriptional hubs of diverse signalling components regulating major developmental transitions in plant and animal systems.


1Integration of Light and Photoperiodic Signaling in Transcriptional Nuclear Foci., Kaiserli, E., Paldi, K., O'Donnell, L., Batalov, O., Pedmale, U.V., Nusinow, D.A., Kay, S.A., and Chory, J. (2015). Developmental cell 35, 311-321.

Other references

1A zinc knuckle protein that negatively controls morning-specific growth in Arabidopsis thaliana. Loudet, O., Michael, T.P., Burger, B.T., Le Mette, C., Mockler, T.C., Weigel, D., and Chory, J. (2008). Proceedings of the National Academy of Sciences of the United States of America 105, 17193-17198.

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