The photoperiodic response of hypocotyl elongation involves regulation of CDF1 and CDF5 activity

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Fig. S1. Hypocotyl length of WT, cdf5, and CDF5OX (lines 5.7, 1.8 and 10.9) grown for 3 or 4 days in SD (top) or LD (bottom). Data are means ± SEM of at least 35 seedlings. Different letters denote statistically significant differences among means by Tukey test (P < 0.05) relative to its respective WT
Date
2020-05-07
Authors
Martí­n, Guiomar
Veciana, Nil
Boix, Marc
Rovira, Arnau
Henriques, Rossana
Monte, Elena
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John Wiley & Sons, Inc.
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Abstract
Hypocotyl elongation relies on directional cell expansion, a process under light and circadian clock control. Under short photoperiods (SD), hypocotyl elongation in Arabidopsis thaliana follows a rhythmic pattern, a process in which circadian morning-to-midnight waves of the transcriptional repressors PSEUDO-RESPONSE REGULATORS (PRRs) jointly gate PHYTOCHROME-INTERACTING FACTOR (PIF) activity to dawn. Previously, we described CYCLING DOF FACTOR 5 (CDF5) as a target of this antagonistic PRR/PIF dynamic interplay. Under SD, PIFs induce CDF5 accumulation specifically at dawn, when it promotes the expression of positive cell elongation regulators such as YUCCA8 to induce growth. In contrast to SD, hypocotyl elongation under long days (LD) is largely reduced. Here, we examine whether CDF5 is an actor in this photoperiod specific regulation. We report that transcription of CDF5 is robustly induced in SD compared to LD, in accordance with PIFs accumulating to higher levels in SD, and in contrast to other members of the CDF family, whose expression is mainly clock regulated and have similar waveforms in SD and LD. Notably, when CDF5 was constitutively expressed under LD, CDF5 protein accumulated to levels comparable to SD but was inactive in promoting cell elongation. Similar results were observed for CDF1. Our findings indicate that both CDFs can promote cell elongation specifically in shorter photoperiods, however their activity in LD is inhibited at the post-translational level. These data not only expand our understanding of the biological role of CDF transcription factors, but also identify a previously unrecognized regulatory layer in the photoperiodic response of hypocotyl elongation.
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Keywords
CDF transcription factors , Hypocotyl elongation , Photoperiodic response
Citation
Martín, G., Veciana, N., Boix, M., Rovira, A., Henriques, R. and Monte, E. (2020) 'The photoperiodic response of hypocotyl elongation involves regulation of CDF1 and CDF5 activity', Physiologia Plantarum. doi: 10.1111/ppl.13119
Copyright
© 2020, John Wiley & Sons, Inc. This is the peer reviewed version of the following article: Martín, G., Veciana, N., Boix, M., Rovira, A., Henriques, R. and Monte, E. (2020) 'The photoperiodic response of hypocotyl elongation involves regulation of CDF1 and CDF5 activity', Physiologia Plantarum, doi: 10.1111/ppl.13119, which has been published in final form at https://doi.org/10.1111/ppl.13119. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.