151
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Vaddepalli P, Scholz S, Schneitz K. Pattern formation during early floral development. Curr Opin Genet Dev 2015; 32:16-23. [DOI: 10.1016/j.gde.2015.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 01/20/2015] [Accepted: 01/21/2015] [Indexed: 10/24/2022]
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152
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Creff A, Brocard L, Ingram G. A mechanically sensitive cell layer regulates the physical properties of the Arabidopsis seed coat. Nat Commun 2015; 6:6382. [DOI: 10.1038/ncomms7382] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 01/23/2015] [Indexed: 01/28/2023] Open
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153
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FT-like proteins induce transposon silencing in the shoot apex during floral induction in rice. Proc Natl Acad Sci U S A 2015; 112:E901-10. [PMID: 25675495 DOI: 10.1073/pnas.1417623112] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Floral induction is a crucial developmental step in higher plants. Florigen, a mobile floral activator that is synthesized in the leaf and transported to the shoot apex, was recently identified as a protein encoded by FLOWERING LOCUS T (FT) and its orthologs; the rice florigen is Heading date 3a (Hd3a) protein. The 14-3-3 proteins mediate the interaction of Hd3a with the transcription factor OsFD1 to form a ternary structure called the florigen activation complex on the promoter of OsMADS15, a rice APETALA1 ortholog. However, crucial information, including the spatiotemporal overlap among FT-like proteins and the components of florigen activation complex and downstream genes, remains unclear. Here, we confirm that Hd3a coexists, in the same regions of the rice shoot apex, with the other components of the florigen activation complex and its transcriptional targets. Unexpectedly, however, RNA-sequencing analysis of shoot apex from wild-type and RNA-interference plants depleted of florigen activity revealed that 4,379 transposable elements (TEs; 58% of all classifiable rice TEs) were expressed collectively in the vegetative and reproductive shoot apex. Furthermore, in the reproductive shoot apex, 214 TEs were silenced by florigen. Our results suggest a link between floral induction and regulation of TEs.
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Crocco CD, Locascio A, Escudero CM, Alabadí D, Blázquez MA, Botto JF. The transcriptional regulator BBX24 impairs DELLA activity to promote shade avoidance in Arabidopsis thaliana. Nat Commun 2015; 6:6202. [PMID: 25656233 DOI: 10.1038/ncomms7202] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 01/05/2015] [Indexed: 11/08/2022] Open
Abstract
In response to canopy shade, plant vegetative structures elongate to gain access to light. However, the mechanism that allows a plastic transcriptional response to canopy shade light is not fully elucidated. Here we propose that the activity of PIF4, a key transcription factor in the shade signalling network, is modulated by the interplay between the BBX24 transcriptional regulator and DELLA proteins, which are negative regulators of the gibberellin (GA) signalling pathway. We show that GA-related targets are enriched among genes responsive to BBX24 under shade and that the shade-response defect in bbx24 mutants is rescued by a GA treatment that promotes DELLA degradation. BBX24 physically interacts with DELLA proteins and alleviates DELLA-mediated repression of PIF4 activity. The proposed molecular mechanism provides reversible regulation of the activity of a key transcription factor that may prove especially relevant under fluctuating light conditions.
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Affiliation(s)
- Carlos D Crocco
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, Avenue San Martín 4453, Buenos Aires C1417DSE, Argentina
| | - Antonella Locascio
- 1] Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia 46022, Spain [2] Department of Agronomy, Food, Natural Resources, Animals and the Environment (DAFNAE), Padova University, Viale dell'Universitá 16, Legnaro 35020, Italy
| | - Cristian M Escudero
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, Avenue San Martín 4453, Buenos Aires C1417DSE, Argentina
| | - David Alabadí
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia 46022, Spain
| | - Miguel A Blázquez
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia 46022, Spain
| | - Javier F Botto
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, Avenue San Martín 4453, Buenos Aires C1417DSE, Argentina
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155
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Saito H, Oikawa T, Hamamoto S, Ishimaru Y, Kanamori-Sato M, Sasaki-Sekimoto Y, Utsumi T, Chen J, Kanno Y, Masuda S, Kamiya Y, Seo M, Uozumi N, Ueda M, Ohta H. The jasmonate-responsive GTR1 transporter is required for gibberellin-mediated stamen development in Arabidopsis. Nat Commun 2015; 6:6095. [PMID: 25648767 PMCID: PMC4347201 DOI: 10.1038/ncomms7095] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 12/14/2014] [Indexed: 12/20/2022] Open
Abstract
Plant hormones are transported across cell membranes during various physiological events. Recent identification of abscisic acid and strigolactone transporters suggests that transport of various plant hormones across membranes does not occur by simple diffusion but requires transporter proteins that are strictly regulated during development. Here, we report that a major glucosinolate transporter, GTR1/NPF2.10, is multifunctional and may be involved in hormone transport in Arabidopsis thaliana. When heterologously expressed in oocytes, GTR1 transports jasmonoyl-isoleucine and gibberellin in addition to glucosinolates. gtr1 mutants are severely impaired in filament elongation and anther dehiscence resulting in reduced fertility, but these phenotypes can be rescued by gibberellin treatment. These results suggest that GTR1 may be a multifunctional transporter for the structurally distinct compounds glucosinolates, jasmonoyl-isoleucine and gibberellin, and may positively regulate stamen development by mediating gibberellin supply. GTR1 is known to transport glucosinolates in Arabidopsis. Here, Saito et al. show that GTR1 also transports the plant hormones jasmonate and gibberellin when heterologously expressed in Xenopus oocytes, and that gtr1 mutant plants show a gibberellin-related fertility phenotype.
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Affiliation(s)
- Hikaru Saito
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B65 Nagatsuta-cho Midori-ku, Yokohama 226-8501, Japan
| | - Takaya Oikawa
- Graduate School of Science, Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-ku, Sendai 980-0845, Japan
| | - Shin Hamamoto
- Graduate School of Engineering, Tohoku University, 6-6-07, Aobayama, Aoba-ku, Sendai 980-8579, Japan
| | - Yasuhiro Ishimaru
- Graduate School of Science, Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-ku, Sendai 980-0845, Japan
| | - Miyu Kanamori-Sato
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B65 Nagatsuta-cho Midori-ku, Yokohama 226-8501, Japan
| | - Yuko Sasaki-Sekimoto
- Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1-IE-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
| | - Tomoya Utsumi
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B65 Nagatsuta-cho Midori-ku, Yokohama 226-8501, Japan
| | - Jing Chen
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B65 Nagatsuta-cho Midori-ku, Yokohama 226-8501, Japan
| | - Yuri Kanno
- RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho Tsurumi-ku, Yokohama 230-0045, Japan
| | - Shinji Masuda
- 1] Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1-IE-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan [2] Center for Biological Resources and Informatics, Tokyo Institute of Technology, 4259-B65 Nagatsuta-cho Midori-ku, Yokohama 226-8501, Japan
| | - Yuji Kamiya
- RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho Tsurumi-ku, Yokohama 230-0045, Japan
| | - Mitsunori Seo
- RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho Tsurumi-ku, Yokohama 230-0045, Japan
| | - Nobuyuki Uozumi
- Graduate School of Engineering, Tohoku University, 6-6-07, Aobayama, Aoba-ku, Sendai 980-8579, Japan
| | - Minoru Ueda
- Graduate School of Science, Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-ku, Sendai 980-0845, Japan
| | - Hiroyuki Ohta
- 1] Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B65 Nagatsuta-cho Midori-ku, Yokohama 226-8501, Japan [2] Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1-IE-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
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156
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Gaillochet C, Daum G, Lohmann JU. O cell, where art thou? The mechanisms of shoot meristem patterning. CURRENT OPINION IN PLANT BIOLOGY 2015; 23:91-7. [PMID: 25449732 DOI: 10.1016/j.pbi.2014.11.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 10/20/2014] [Accepted: 11/02/2014] [Indexed: 05/05/2023]
Abstract
Plants develop postembryonically from pools of continuously active stem cells embedded in specialized tissues called meristems, which are located at the growing points of shoot and root. How these stem cells are established, maintained and guided towards differentiation within the highly dynamic shoot apical meristem is only beginning to emerge. At the core of the complex regulatory system are spatially distinct subdomains within the shoot apex, in which cells carry out defined functions, despite highly similar phenotypes. Spatial and temporal control of these domains appears to rely on an elaborate network of phytohormone signaling, transcriptional loops and intercellular trafficking of key regulators. In this review, we aim at summarizing and connecting the mechanisms underlying the spatial organization of the shoot apical meristem and the sequence of molecular events occurring during the life of a shoot cell, from its birth towards its differentiation.
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Affiliation(s)
- Christophe Gaillochet
- Department of Stem Cell Biology, Centre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany
| | - Gabor Daum
- Department of Stem Cell Biology, Centre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany
| | - Jan U Lohmann
- Department of Stem Cell Biology, Centre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany.
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157
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Takeda N, Handa Y, Tsuzuki S, Kojima M, Sakakibara H, Kawaguchi M. Gibberellins interfere with symbiosis signaling and gene expression and alter colonization by arbuscular mycorrhizal fungi in Lotus japonicus. PLANT PHYSIOLOGY 2015; 167:545-57. [PMID: 25527715 PMCID: PMC4326748 DOI: 10.1104/pp.114.247700] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Accepted: 12/17/2014] [Indexed: 05/06/2023]
Abstract
Arbuscular mycorrhiza is a mutualistic plant-fungus interaction that confers great advantages for plant growth. Arbuscular mycorrhizal (AM) fungi enter the host root and form symbiotic structures that facilitate nutrient supplies between the symbionts. The gibberellins (GAs) are phytohormones known to inhibit AM fungal infection. However, our transcriptome analysis and phytohormone quantification revealed GA accumulation in the roots of Lotus japonicus infected with AM fungi, suggesting that de novo GA synthesis plays a role in arbuscular mycorrhiza development. We found pleiotropic effects of GAs on the AM fungal infection. In particular, the morphology of AM fungal colonization was drastically altered by the status of GA signaling in the host root. Exogenous GA treatment inhibited AM hyphal entry into the host root and suppressed the expression of Reduced Arbuscular Mycorrhization1 (RAM1) and RAM2 homologs that function in hyphal entry and arbuscule formation. On the other hand, inhibition of GA biosynthesis or suppression of GA signaling also affected arbuscular mycorrhiza development in the host root. Low-GA conditions suppressed arbuscular mycorrhiza-induced subtilisin-like serine protease1 (SbtM1) expression that is required for AM fungal colonization and reduced hyphal branching in the host root. The reduced hyphal branching and SbtM1 expression caused by the inhibition of GA biosynthesis were recovered by GA treatment, supporting the theory that insufficient GA signaling causes the inhibitory effects on arbuscular mycorrhiza development. Most studies have focused on the negative role of GA signaling, whereas our study demonstrates that GA signaling also positively interacts with symbiotic responses and promotes AM colonization of the host root.
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Affiliation(s)
- Naoya Takeda
- Division of Symbiotic Systems, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, Japan (N.T., Y.H., M.Ka.);Department of Basic Biology, Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan (N.T., S.T., M.Ka.); andPlant Productivity Systems Research Group, RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama 230-0045, Japan (M.Ko., H.S.)
| | - Yoshihiro Handa
- Division of Symbiotic Systems, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, Japan (N.T., Y.H., M.Ka.);Department of Basic Biology, Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan (N.T., S.T., M.Ka.); andPlant Productivity Systems Research Group, RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama 230-0045, Japan (M.Ko., H.S.)
| | - Syusaku Tsuzuki
- Division of Symbiotic Systems, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, Japan (N.T., Y.H., M.Ka.);Department of Basic Biology, Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan (N.T., S.T., M.Ka.); andPlant Productivity Systems Research Group, RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama 230-0045, Japan (M.Ko., H.S.)
| | - Mikiko Kojima
- Division of Symbiotic Systems, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, Japan (N.T., Y.H., M.Ka.);Department of Basic Biology, Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan (N.T., S.T., M.Ka.); andPlant Productivity Systems Research Group, RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama 230-0045, Japan (M.Ko., H.S.)
| | - Hitoshi Sakakibara
- Division of Symbiotic Systems, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, Japan (N.T., Y.H., M.Ka.);Department of Basic Biology, Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan (N.T., S.T., M.Ka.); andPlant Productivity Systems Research Group, RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama 230-0045, Japan (M.Ko., H.S.)
| | - Masayoshi Kawaguchi
- Division of Symbiotic Systems, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, Japan (N.T., Y.H., M.Ka.);Department of Basic Biology, Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan (N.T., S.T., M.Ka.); andPlant Productivity Systems Research Group, RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama 230-0045, Japan (M.Ko., H.S.)
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158
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Yamaguchi N, Winter CM, Wellmer F, Wagner D. Identification of direct targets of plant transcription factors using the GR fusion technique. Methods Mol Biol 2015; 1284:123-38. [PMID: 25757770 PMCID: PMC5757826 DOI: 10.1007/978-1-4939-2444-8_6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The glucocorticoid receptor-dependent activation of plant transcription factors has proven to be a powerful tool for the identification of their direct target genes. In the absence of the synthetic steroid hormone dexamethasone (dex), transcription factors fused to the hormone-binding domain of the glucocorticoid receptor (TF-GR) are held in an inactive state, due to their cytoplasmic localization. This requires physical interaction with the heat shock protein 90 (HSP90) complex. Hormone binding leads to disruption of the interaction between GR and HSP90 and allows TF-GR fusion proteins to enter the nucleus. Once inside the nucleus, they bind to specific DNA sequences and immediately activate or repress expression of their targets. This system is well suited for the identification of direct target genes of transcription factors in plants, as (A) there is little basal protein activity in the absence of dex, (B) steroid application leads to rapid transcription factor activation, (C) no side effects of dex treatment are observed on the physiology of the plant, and (D) secondary effects of transcription factor activity can be eliminated by simultaneous application of an inhibitor of protein biosynthesis, cycloheximide (cyc). In this chapter, we describe detailed protocols for the preparation of plant material, for dex and cyc treatment, for RNA extraction, and for the PCR-based or genome-wide identification of direct targets of transcription factors fused to GR.
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Affiliation(s)
- Nobutoshi Yamaguchi
- Department of Biology, University of Pennsylvania, 415 S. University Ave., Philadelphia, PA, 19104-6018, USA
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159
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Golembeski GS, Imaizumi T. Photoperiodic Regulation of Florigen Function in Arabidopsis thaliana. THE ARABIDOPSIS BOOK 2015; 13:e0178. [PMID: 26157354 PMCID: PMC4489636 DOI: 10.1199/tab.0178] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
One mechanism through which flowering in response to seasonal change is brought about is by sensing the fluctuation in day-length; the photoperiod. Flowering induction occurs through the production of the florigenic protein FLOWERING LOCUS T (FT) and its movement from the phloem companion cells in the leaf vasculature into the shoot apex, where meristematic reprogramming occurs. FT activation in response to photoperiod condition is accomplished largely through the activity of the transcription factor CONSTANS (CO). Regulation of CO expression and protein stability, as well as the timing of other components via the circadian clock, is a critical mechanism by which plants are able to respond to photoperiod to initiate the floral transition. Modulation of FT expression in response to external and internal stimuli via components of the flowering network is crucial to mediate a fluid flowering response to a variety of environmental parameters. In addition, the regulated movement of FT protein from the phloem to the shoot apex, and interactions that determine floral meristem cell fate, constitute novel mechanisms through which photoperiodic information is translated into flowering time.
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Affiliation(s)
- Greg S. Golembeski
- University of Washington, Department of Biology, Seattle, WA, 98195-1800
| | - Takato Imaizumi
- University of Washington, Department of Biology, Seattle, WA, 98195-1800
- Address correspondence to
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160
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Friedman J, Twyford AD, Willis JH, Blackman BK. The extent and genetic basis of phenotypic divergence in life history traits in Mimulus guttatus. Mol Ecol 2014; 24:111-22. [PMID: 25403267 PMCID: PMC4657477 DOI: 10.1111/mec.13004] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 10/26/2014] [Accepted: 11/06/2014] [Indexed: 12/13/2022]
Abstract
Differential natural selection acting on populations in contrasting environments often results in adaptive divergence in multivariate phenotypes. Multivariate trait divergence across populations could be caused by selection on pleiotropic alleles or through many independent loci with trait-specific effects. Here, we assess patterns of association between a suite of traits contributing to life history divergence in the common monkey flower, Mimulus guttatus, and examine the genetic architecture underlying these correlations. A common garden survey of 74 populations representing annual and perennial strategies from across the native range revealed strong correlations between vegetative and reproductive traits. To determine whether these multitrait patterns arise from pleiotropic or independent loci, we mapped QTLs using an approach combining high-throughput sequencing with bulk segregant analysis on a cross between populations with divergent life histories. We find extensive pleiotropy for QTLs related to flowering time and stolon production, a key feature of the perennial strategy. Candidate genes related to axillary meristem development colocalize with the QTLs in a manner consistent with either pleiotropic or independent QTL effects. Further, these results are analogous to previous work showing pleiotropy-mediated genetic correlations within a single population of M. guttatus experiencing heterogeneous selection. Our findings of strong multivariate trait associations and pleiotropic QTLs suggest that patterns of genetic variation may determine the trajectory of adaptive divergence.
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Affiliation(s)
- Jannice Friedman
- Department of Biology, Syracuse University, 110 College Place, Syracuse, NY, 13244, USA
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161
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Wang CQ, Guthrie C, Sarmast MK, Dehesh K. BBX19 interacts with CONSTANS to repress FLOWERING LOCUS T transcription, defining a flowering time checkpoint in Arabidopsis. THE PLANT CELL 2014; 26:3589-602. [PMID: 25228341 PMCID: PMC4213167 DOI: 10.1105/tpc.114.130252] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The timely transition of vegetative to reproductive development is coordinated through quantitative regulation of floral pathway genes in response to physiological and environmental cues. Here, we show that the circadian-controlled expression of the Arabidopsis thaliana floral transition regulators FLOWERING LOCUS T (FT) and CONSTANS (CO) is antiphasic to that of BBX19, a transcription factor with two B-Box motifs. Diminished expression of BBX19 by RNA interference accelerates flowering, and constitutive expression of BBX19 delays flowering under inductive photoperiods. This delay is not accompanied by the alteration of CO expression levels but rather by a reduction of transcript levels of FT and the FT-regulated genes SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1, LEAFY, and FRUITFUL. Similar to CO, BBX19 is expressed in vasculature. BBX19 and CO colocalize in the nucleus and interact physically in vivo. In transient assays, coinfiltration of 10-fold more CO overcomes the BBX19-mediated repression of FT activation. Substitution of the conserved Cys-25 to Ser in the BBX19 Box1 motif abolishes the BBX19-CO interaction and eliminates the negative regulation of flowering time, while the analogous C76S substitution in the Box2 motif is ineffective. Together, these results implicate BBX19 as a circadian clock output that depletes the active CO pool to accurately monitor daylength and precisely time FT expression.
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Affiliation(s)
- Chang-Quan Wang
- Department of Plant Biology, University of California, Davis, California 95616
| | - Cade Guthrie
- Department of Plant Biology, University of California, Davis, California 95616
| | | | - Katayoon Dehesh
- Department of Plant Biology, University of California, Davis, California 95616
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