Category: Publications

Citation:

Winter, CM, Austin RS, Blanvillain-Baufume S, Reback MA, Monniaux M, Wu MF, Sang Y, Yamaguchi A, Yamaguchi N, Parker JE, Parcy F, Jensen ST, Li H, Wagner D.  2011.  LEAFY Target Genes Reveal Floral Regulatory Logic, cis Motifs, and a Link to Biotic Stimulus Response, Apr 19. Dev Cell. 20:430-43., Number 4

Abstract:

The transition from vegetative growth to flower formation is critical for the survival of flowering plants. The plant-specific transcription factor LEAFY (LFY) has central, evolutionarily conserved roles in this process, both in the formation of the first flower and later in floral patterning. We performed genome-wide binding and expression studies to elucidate the molecular mechanisms by which LFY executes these roles. Our study reveals that LFY directs an elaborate regulatory network in control of floral homeotic gene expression. LFY also controls the expression of genes that regulate the response to external stimuli in Arabidopsis. Thus, our findings support a key role for LFY in the coordination of reproductive stage development and disease response programs in plants that may ensure optimal allocation of plant resources for reproductive fitness. Finally, motif analyses reveal a possible mechanism for stage-specific LFY recruitment and suggest a role for LFY in overcoming polycomb repression.

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1878-1551 (Electronic)1534-5807 (Linking)Journal Article

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Sang, Y, Wu MF, Wagner D.  2009.  The stem cell–chromatin connection, Dec. Semin Cell Dev Biol. 20:1143-8., Number 9

Abstract:

Stem cells self-renew and give rise to all differentiated cell types of the adult body. They are classified as toti-, pluri- or multi-potent based on the number of different cell types they can give rise to. Recently it has become apparent that chromatin regulation plays a critical role in determining the fate of stem cells and their descendants. In this review we will discuss the role of chromatin regulators in maintenance of stem cells and their ability to give rise to differentiating cells in both the animal and plant kingdom. We will highlight similarities and differences in chromatin-mediated control of stem cell fate in plants and animals. We will consider possible reasons why chromatin regulators play a central role in pluripotency in both kingdoms given that multicellularity evolved independently in each.

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Sang, YiWu, Miin-FengWagner, DorisResearch Support, N.I.H., ExtramuralResearch Support, U.S. Gov’t, Non-P.H.S.EnglandSeminars in cell & developmental biologySemin Cell Dev Biol. 2009 Dec;20(9):1143-8. Epub 2009 Sep 16.

Citation:

Abstract:

When to form flowers is a developmental decision that profoundly impacts the fitness of flowering plants. In Arabidopsis this decision is ultimately controlled by the induction and subsequent activity of the transcription factors LEAFY (LFY), FRUITFULL (FUL), and APETALA1 (AP1). Despite their central importance, our current understanding of the regulation of LFY, FUL, and AP1 expression is still incomplete. We show here that all three genes are directly activated by the microRNA-targeted transcription factor SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 3 (SPL3). Our findings suggest that SPL3 acts together with other microRNA-regulated SPL transcription factors to control the timing of flower formation. Moreover, the identified SPL activity defines a distinct pathway in control of this vital developmental decision.

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R01 GM051893/GM/NIGMS NIH HHS/United StatesJournal ArticleResearch Support, N.I.H., ExtramuralResearch Support, Non-U.S. Gov’tResearch Support, U.S. Gov’t, Non-P.H.S.United States

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Abstract:

Flowers are unique parts of plants because they form a predictable number of organs of defined identity. This exquisite regularity defines entire plant families and has been used for taxonomic classification since ancient times. In this issue of Developmental Cell, Liu et al. reveal that timing of the onset of flower differentiation is key for the stereotypic architecture of flowers.

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CommentJournal ArticleUnited States

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Abstract:

Genetic analyses in model angiosperms have shown that the LEAFY/FLORICAULA transcription factor plays a central role in flower development. In Arabidopsis, LEAFY (LFY) triggers the development of floral meristems and controls their patterning through the activation of floral organ identity genes. Several recent reports enlighten the structure and function of this conserved protein but also illustrate the variety of roles it plays in different angiosperms.

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Walley, JW, Rowe HC, Xiao Y, Chehab EW, Kliebenstein DJ, Wagner D, Dehesh K.  2008.  The chromatin remodeler SPLAYED regulates specific stress signaling pathways, Dec. PLoS Pathog. 4:e1000237., Number 12

Abstract:

Organisms are continuously exposed to a myriad of environmental stresses. Central to an organism’s survival is the ability to mount a robust transcriptional response to the imposed stress. An emerging mechanism of transcriptional control involves dynamic changes in chromatin structure. Alterations in chromatin structure are brought about by a number of different mechanisms, including chromatin modifications, which covalently modify histone proteins; incorporation of histone variants; and chromatin remodeling, which utilizes ATP hydrolysis to alter histone-DNA contacts. While considerable insight into the mechanisms of chromatin remodeling has been gained, the biological role of chromatin remodeling complexes beyond their function as regulators of cellular differentiation and development has remained poorly understood. Here, we provide genetic, biochemical, and biological evidence for the critical role of chromatin remodeling in mediating plant defense against specific biotic stresses. We found that the Arabidopsis SWI/SNF class chromatin remodeling ATPase SPLAYED (SYD) is required for the expression of selected genes downstream of the jasmonate (JA) and ethylene (ET) signaling pathways. SYD is also directly recruited to the promoters of several of these genes. Furthermore, we show that SYD is required for resistance against the necrotrophic pathogen Botrytis cinerea but not the biotrophic pathogen Pseudomonas syringae. These findings demonstrate not only that chromatin remodeling is required for selective pathogen resistance, but also that chromatin remodelers such as SYD can regulate specific pathways within biotic stress signaling networks.

Notes:

R01 GM064650-01/GM/NIGMS NIH HHS/United StatesT32 GM070377/GM/NIGMS NIH HHS/United StatesJournal ArticleResearch Support, N.I.H., ExtramuralResearch Support, U.S. Gov’t, Non-P.H.S.United States

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Abstract:

In all eukaryotes chromatin physically restricts the accessibility of the genome to regulatory proteins such as transcription factors. Plant model systems have been instrumental in demonstrating that this restriction is dynamic and changes during development and in response to exogenous cues. Among the multiple epigenetic mechanisms that alter chromatin to regulate gene expression, histone modifications play a major role. Recent studies in Arabidopsis have provided the first genome-wide histone modification maps, revealed important biological roles for histone modifications, and advanced our understanding of stimulus-dependent changes in histone modifications.

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F32-GM076933/GM/United States NIGMSR01 GM064650-01A2/GM/United States NIGMSR01 GM64650-01/GM/United States NIGMSJournal ArticleResearch Support, N.I.H., ExtramuralResearch Support, U.S. Gov’t, Non-P.H.S.ReviewEngland

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Abstract:

SWI/SNF chromatin remodeling ATPases control accessibility of the information stored in the genome. However, the in vivo role of these remodelers has remained poorly understood because null mutations in these result in embryonic lethality in most organisms. Recently, the study of conditional mutants in mammals and viable null mutants in plants, combined with genome wide expression studies in mammals, flies and plants, have implicated chromatin remodeling ATPases in the regulation of many developmental pathways in multicellular eukaryotes. In addition, these studies reveal striking functional specificity for chromatin remodeling in individual developmental processes.

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R01 gm064650-01/gm/nigmsJournal ArticleResearch Support, N.I.H., ExtramuralResearch Support, Non-U.S. Gov’tReviewEnglandTig

Citation:

Abstract:

Chromatin remodeling is emerging as a central mechanism for patterning and differentiation in multicellular eukaryotes. SWI/SNF chromatin remodeling ATPases are conserved in the animal and plant kingdom and regulate transcriptional programs in response to endogenous and exogenous cues. In contrast with their metazoan orthologs, null mutants in two Arabidopsis thaliana SWI/SNF ATPases, BRAHMA (BRM) and SPLAYED (SYD), are viable, facilitating investigation of their role in the organism. Previous analyses revealed that syd and brm null mutants exhibit both similar and distinct developmental defects, yet the functional relationship between the two closely related ATPases is not understood. Another central question is whether these proteins act as general or specific transcriptional regulators. Using global expression studies, double mutant analysis, and protein interaction assays, we find overlapping functions for the two SWI/SNF ATPases. This partial diversification may have allowed expansion of the SWI/SNF ATPase regulatory repertoire, while preserving essential ancestral functions. Moreover, only a small fraction of all genes depends on SYD or BRM for expression, indicating that these SWI/SNF ATPases exhibit remarkable regulatory specificity. Our studies provide a conceptual framework for understanding the role of SWI/SNF chromatin remodeling in regulation of Arabidopsis development.

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1040-4651 (Print)Journal article

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