<i>Arabidopsis</i> TOE proteins convey a photoperiodic signal to antagonize CONSTANS and regulate flowering time

Zhang, Bailong; Wang, Liang; Zeng, Liping; Zhang, Chao; Mā, Hong

doi:10.1101/gad.251520.114

Cited by 151 publications

(161 citation statements)

References 45 publications

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“…Finally, in the prr9 mutant where the circadian clock is not strongly affected in light/dark cycles (Appendix Fig S2G; Ito et al , 2003; Farré et al , 2005), HA:CO protein abundance was strongly reduced in the morning when PRR9 is expressed in WT plants (Figs 3I–L and EV3A). Another clock‐controlled gene TOE1 was reported to reduce CO protein abundance under LD (Zhang et al , 2015), and we found that its mRNA levels were increased in toc1 prr5 prr7 prr9 SUC2 :: HA:CO , suggesting that this might contribute to the observed reduction in CO protein abundance (Appendix Fig S2H and I). However, in prr9 SUC2 :: HA:CO where CO protein level is reduced specifically in the morning, TOE1 mRNA level was not increased at this time (Appendix Fig S2H and I).…”

Section: Resultssupporting

confidence: 57%

“…In addition to COP1 and FKF1 that were discussed above, HOS1 and TOE1 have also been implicated in regulating CO stability (Lazaro et al , 2012; Zhang et al , 2015). Although it is possible that HOS1 and TOE1 might also be regulated by PRRs, our genetic data with the cop1 toc1 prr5 prr7 prr9 quintuple mutant do not currently support this hypothesis, because the cop1 mutation is epistatic to the prr mutations with respect to CO protein abundance (Fig 4E and F).…”

Section: Discussionmentioning

confidence: 99%

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PSEUDO RESPONSE REGULATORs stabilize CONSTANS protein to promote flowering in response to day length

et al. 2017

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Seasonal reproduction in many organisms requires detection of day length. This is achieved by integrating information on the light environment with an internal photoperiodic time‐keeping mechanism. Arabidopsis thaliana promotes flowering in response to long days (LDs), and CONSTANS (CO) transcription factor represents a photoperiodic timer whose stability is higher when plants are exposed to light under LDs. Here, we show that PSEUDO RESPONSE REGULATOR (PRR) proteins directly mediate this stabilization. PRRs interact with and stabilize CO at specific times during the day, thereby mediating its accumulation under LDs. PRR‐mediated stabilization increases binding of CO to the promoter of FLOWERING LOCUS T (FT), leading to enhanced FT transcription and early flowering under these conditions. PRRs were previously reported to contribute to timekeeping by regulating CO transcription through their roles in the circadian clock. We propose an additional role for PRRs in which they act upon CO protein to promote flowering, directly coupling information on light exposure to the timekeeper and allowing recognition of LDs.

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Section: Resultssupporting

confidence: 57%

Section: Discussionmentioning

confidence: 99%

PSEUDO RESPONSE REGULATORs stabilize CONSTANS protein to promote flowering in response to day length

et al. 2017

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“…As shown in Figure 6B, TOE1 enrichment levels at region C (located in the upstream region of FT) and region R (located in the downstream region of FT) were markedly higher than those at other regions. It was recently shown that TOE1 also associates with the FT promoter at region F and region H ( Figure 6A), which contain AT-rich elements (Dinh et al, 2012;Zhang et al, 2015). In our ChIP-qPCR experiments, however, TOE1 enrichment levels at region F and region H were much lower than those at region C and region R ( Figure 6B).…”

Section: Toe1 Binds the Promoter And Downstream Regulatory Region Ofcontrasting

confidence: 47%

Transcriptional Mechanism of Jasmonate Receptor COI1-Mediated Delay of Flowering Time in Arabidopsis

Zhai¹,

Zhang²,

Wu³

et al. 2015

Plant Cell

167

163

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Flowering time of plants must be tightly regulated to maximize reproductive success. Plants have evolved sophisticated signaling network to coordinate the timing of flowering in response to their ever-changing environmental conditions. Besides being a key immune signal, the lipid-derived plant hormone jasmonate (JA) also regulates a wide range of developmental processes including flowering time. Here, we report that the CORONATINE INSENSITIVE1 (COI1)-dependent signaling pathway delays the flowering time of Arabidopsis thaliana by inhibiting the expression of the florigen gene FLOWERING LOCUS T (FT). We provide genetic and biochemical evidence that the APETALA2 transcription factors (TFs) TARGET OF EAT1 (TOE1) and TOE2 interact with a subset of JAZ (jasmonate-ZIM domain) proteins and repress the transcription of FT. Our results support a scenario that, when plants encounter stress conditions, bioactive JA promotes COI1-dependent degradation of JAZs. Degradation of the JAZ repressors liberates the transcriptional function of the TOEs to repress the expression of FT and thereby triggers the signaling cascades to delay flowering. Our study identified interacting pairs of TF and JAZ transcriptional regulators that underlie JA-mediated regulation of flowering, suggesting that JA signals are converted into specific context-dependent responses by matching pairs of TF and JAZ proteins.

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“…These AP2 type proteins are age-dependent regulators of FT, as they are posttranscriptionally regulated by miR172 (Aukerman and Sakai, 2003;Chen, 2004;Song et al, 2013). TOE1 also represses FT expression by physically suppressing the function of CO on the FT promoter (Zhang et al, 2015). TOE1-dependent suppression of FT requires its EAR-like motif, a binding site of TPL.…”

Section: Posttranslational Regulation Of Co Proteinmentioning

confidence: 99%

Circadian Clock and Photoperiodic Flowering in Arabidopsis: CONSTANS Is a Hub for Signal Integration

2016

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Plants sense changes in day length (= photoperiod) as a reliable seasonal cue to regulate important developmental transitions such as flowering. Integration of various external light information into the circadian clock-controlled mechanisms enables plants to precisely measure photoperiod changes in the surrounding environment. The core mechanism of photoperiodic measurement is regulation of CONSTANS (CO) activity, which takes place in phloem companion cells in leaves. Until recently, it remained unclear whether plants possess specific variations of the clock for this regulation. Now it is known that a specific circadian timing mechanism in the vascular tissue is essential for photoperiodic flowering. In addition to spatial tissue-specific regulation, temporal regulation of CO activity is also important. The identification and characterization of multiple regulators that physically interact with CO and influence its function in the morning in long days are two recent advances in photoperiodic regulation of flowering time. It seems that CO acts as a network hub to integrate various external and internal signals into the photoperiodic flowering pathway. CO regulates the amount of FLOWERING LOCUS T (FT) transcripts and FT protein moves from companion cells of leaf phloem to the shoot apical meristem. The protein that helps long-distance transport of FT protein was also identified recently. Here, we introduce recent advances in tissue-specific variations of the circadian clock and the emerging picture of the intricate connections of transcriptional regulators through CO in the morning, which all facilitate plants knowing when to flower.Properly timing the floral transition is crucial for reproductive success. It can also influence the early development of offspring. To optimize this timing, plants constantly monitor changes in the surrounding environment. Among various environmental factors, observing changes in day length (= photoperiod) is the most reliable way for many organisms to know the specific time of year. Therefore, photoperiodic regulation is one of the major flowering time mechanisms and it has been studied since it was first reported in 1920 (Song et al., 2015). Arabidopsis (Arabidopsis thaliana), as it flowers mainly in spring, can sense lengthening days to induce flowering and became a suitable model to study photoperiodic flowering regulation. (Andrés and Coupland, 2012;Song et al., 2013;Pajoro et al., 2014;Shim and Imaizumi, 2015).In principle, photoperiodic flowering mechanisms can be divided into three parts: light input, circadian clock, and output. Light information is integrated into innate photoperiodic timing mechanisms governed by the circadian clock to induce genes that trigger flowering.

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Arabidopsis TOE proteins convey a photoperiodic signal to antagonize CONSTANS and regulate flowering time

Cited by 151 publications

References 45 publications

PSEUDO RESPONSE REGULATORs stabilize CONSTANS protein to promote flowering in response to day length

PSEUDO RESPONSE REGULATORs stabilize CONSTANS protein to promote flowering in response to day length

Transcriptional Mechanism of Jasmonate Receptor COI1-Mediated Delay of Flowering Time in Arabidopsis

Circadian Clock and Photoperiodic Flowering in Arabidopsis: CONSTANS Is a Hub for Signal Integration

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