MicroProtein-Mediated Recruitment of CONSTANS into a TOPLESS Trimeric Complex Represses Flowering in Arabidopsis

Graeff, Moritz; Straub, Daniel; Eguen, Tenai; Dolde, Ulla; Rodrigues, Vandasue; Brandt, Ronny; Wenkel, Stephan

doi:10.1371/journal.pgen.1005959

Cited by 134 publications

(192 citation statements)

References 49 publications

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“…The recognition site of MYC2 appears to function as both positive and negative regulator of the expression of the MYC2 promoter-GUS fusion gene (Abe et al, 1997). Recently, CONSTANS, the eponymous member of the family of CONSTANS-like transcriptional regulators, mediates photoperiodic flowering by physically interacting with microproteins, miP1a and miP1b (Graeff et al, 2016). Thus, TFs play a multiple and complicated role in development and stress responses of plants.…”

Section: Discussionmentioning

confidence: 99%

A Rice NAC Transcription Factor Promotes Leaf Senescence via ABA Biosynthesis

et al. 2017

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It is well known that abscisic acid (ABA)-induced leaf senescence and premature leaf senescence negatively affect the yield of rice (Oryza sativa). However, the molecular mechanism underlying this relationship, especially the upstream transcriptional network that modulates ABA level during leaf senescence, remains largely unknown. Here, we demonstrate a rice NAC transcription factor, OsNAC2, that participates in ABA-induced leaf senescence. Overexpression of OsNAC2 dramatically accelerated leaf senescence, whereas its knockdown lines showed a delay in leaf senescence. Chromatin immunoprecipitation-quantitative PCR, dual-luciferase, and yeast one-hybrid assays demonstrated that OsNAC2 directly activates expression of chlorophyll degradation genes, OsSGR and OsNYC3. Moreover, ectopic expression of OsNAC2 leads to an increase in ABA levels via directly up-regulating expression of ABA biosynthetic genes (OsNCED3 and OsZEP1) as well as down-regulating the ABA catabolic gene (OsABA8ox1). Interestingly, OsNAC2 is upregulated by a lower level of ABA but downregulated by a higher level of ABA, indicating a feedback repression of OsNAC2 by ABA. Additionally, reduced OsNAC2 expression leads to about 10% increase in the grain yield of RNAi lines. The novel ABA-NAC-SAGs regulatory module might provide a new insight into the molecular action of ABA to enhance leaf senescence and elucidates the transcriptional network of ABA production during leaf senescence in rice.Senescence is the last stage of leaf development. During this period, various changes occur at the physiological, biochemical, and molecular levels. For example, macromolecules including lipids, proteins, and nucleic acids are hydrolyzed, which leads to disassembly of mitochondria and nuclei, and to cell death (Buchanan-Wollaston et al., 2005;Ulker et al., 2007). Although senescence is an active process to salvage nutrients from old tissues, precocious senescence will shorten the growth stage of crops and be unfavorable to agronomic production (Woo et al., 2013).The most distinguishing feature in leaf senescence is the yellowing phenotype, which is a visible marker of the degradation of macromolecules (Kim et al., 2006). The chlorophyll degradation pathway is one of the most characterized ones for macromolecule degradation in plants (Hörtensteiner, 2006). Overexpressing NON-YELLOW COLORING1 (NYC1) or NYC1-like genes in rice (Oryza sativa) can induce degradation of chlorophyll . A pph (encoding pheophytinase) mutant is abnormal in chlorophyll degradation during senescence and therefore exhibits a stay-green phenotype (Schelbert et al., 2009). Mutation of the PAO (Pheophorbide a oxygenase) gene leads to retention of chlorophyll in leaves during dark-induced senescence in Arabidopsis (Arabidopsis thaliana; Pruzinská et al., 2005). Recently, the highly conserved STAY-GREEN (SGR) in higher plants has been identified to be chloroplast-localized dechelatase (Shimoda et al., 2016).The senescence process is highly regulated by a range of important factors. It has been demon...

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Section: Discussionmentioning

confidence: 99%

A Rice NAC Transcription Factor Promotes Leaf Senescence via ABA Biosynthesis

et al. 2017

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“…B-BOX domain proteins (BBX): BBX19, microProtein 1a (miP1a)/BBX30, and miP1b/BBX31 Graeff et al, 2016;Fig. 2).…”

Section: Posttranslational Regulation Of Co Proteinmentioning

confidence: 99%

“…BBX19 is highly expressed in the morning and BBX19 protein binds to CO to suppress its function; therefore, suppression of BBX19 only affects FT expression in the morning. Two small B-BOX proteins, MiP1a and MiP1b (previously known as BBX30 and BBX31), also form a complex with CO to prevent its function (Khanna et al, 2009;Graeff et al, 2016). Similar to BBX19, MiP1a is highly expressed in the morning in long days.…”

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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“…Among the downregulated genes in co-sail, we find many members of the B-box protein (BBX) family (Khanna et al, 2009), mostly those that do not contain a CCT domain. These include BBX19 (At4g38960), whose protein product interacts with CO and whose reduced expression accelerates flowering , and BBX30 (At4g15248) and BBX31 (At3g21890), which also interact with the CO protein and whose overexpression delays flowering (Graeff et al, 2016), as well as BBX32, which interacts with COL3 to regulate FT (Tripathi et al, 2017).…”

Section: Analysis Of Nf-co-regulated Genesmentioning

confidence: 99%