Citation:
Wagner, D, Saddic LA, Lu M, Kim F, Su Y, William D, Kwon CS. 2003. Meristem identity in Arabidopsis thaliana. Flowering Newsletter . 36:25-35.
Author: klasfeld
CHROMATIN REGULATION OF PLANT DEVELOPMENT
Citation:
Wagner, D. 2003. Chromatin regulation of plant development, Feb. Curr Opin Plant Biol. 6:20-8., Number 1
Abstract:
Chromatin remodeling factors are being identified as genetic modifiers of developmental mutations in plants. These mutations result in lethality in metazoans, whereas in plants, they are viable and affect a wide range of developmental and physiological processes. Recent studies have begun to define the many functions of chromatin remodeling factors in plants and have revealed apparent differences between these factors in the two kingdoms.
Notes:
1369-5266Journal Article
SPLAYED, A NOVEL SWI/SNF ATPASE HOMOLOG, CONTROLS REPRODUCTIVE DEVELOPMENT IN ARABIDOPSIS
Citation:
Wagner, D, Meyerowitz EM. 2002. SPLAYED, a novel SWI/SNF ATPase homolog, controls reproductive development in Arabidopsis, Jan 22. Curr Biol. 12:85-94., Number 2
Abstract:
BACKGROUND: The plant-specific transcriptional activator LEAFY (LFY) is a central regulator of the transition to reproductive development in Arabidopsis. LFY has a second, later role in the induction of floral homeotic gene expression. Available data suggests that, while LFY activity is controlled via interaction with tissue-specific coactivators, other mechanisms exist that regulate LFY activity, the identity of which are not known. RESULTS: We have identified a novel component in the temporal control of the switch from vegetative to reproductive development in Arabidopsis thaliana. The SPLAYED (SYD) gene product acts with LFY to regulate shoot apical meristem identity. SYD is also involved in the regulation of floral homeotic gene expression. In addition, mutations in SYD cause LFY-independent phenotypes that indicate that SYD is necessary for meristem maintenance during reproductive development and that SYD is required for proper carpel and ovule development. SYD encodes a presumptive Arabidopsis homolog of the yeast Snf2p ATPase, which is implicated in transcriptional control via chromatin remodeling. CONCLUSIONS: SYD acts as a LFY-dependent repressor of the meristem identity switch in the floral transition, most likely by altering the activity of the LFY transcription factor. That SYD regulates flowering in response to environmental stimuli suggests that the effect of environmental cues on plant development may be achieved in part by regulating transcription factor activity via alteration of the chromatin state.
Notes:
0960-9822 (Print)Journal ArticleResearch Support, Non-U.S. Gov’tResearch Support, U.S. Gov’t, Non-P.H.S.
GLUCOCORTICOID FUSIONS FOR TRANSCRIPTION FACTOR
Citation:
Wagner, D, Sablowski RW. 2001. Glucocorticoid Fusions for Transcription Factor. In Arabidopsis-A Laboratory Manual. (Weigel, D., Glazebrook, J., Eds.)., Cold Spring Harbor: Cold Spring Harbor Laboratory Press.
Abstract:
TRANSCRIPTIONAL ACTIVATION OF APETALA1 BY LEAFY
Citation:
Wagner, D, Sablowski RW, Meyerowitz EM. 1999. Transcriptional activation of APETALA1 by LEAFY. Science. 285:582-4., Number 5427
Abstract:
Plants produce new appendages reiteratively from groups of stem cells called shoot apical meristems. LEAFY (LFY) and APETALA1 (AP1) are pivotal for the switch to the reproductive phase, where instead of leaves the shoot apical meristem produces flowers. Use of steroid- inducible activation of LFY demonstrated that early expression of AP1 is a result of transcriptional induction by LFY. This AP1 induction is independent of protein synthesis and occurs specifically in the tissues and at the developmental stage in which floral fate is assumed. Later expression of AP1 appears to be only indirectly affected by LFY.
Notes:
n/a
RED1 IS NECESSARY FOR PHYTOCHROME B-MEDIATED RED LIGHT-SPECIFIC SIGNAL TRANSDUCTION IN ARABIDOPSIS
Citation:
Wagner, D, Hoecker U, Quail PH. 1997. RED1 is necessary for phytochrome B-mediated red light-specific signal transduction in Arabidopsis, May. The Plant cell. 9:731-43., Number 5
Abstract:
Seedlings of a transgenic Arabidopsis line (ABO) that overexpresses phytochrome B (phyB) display enhanced deetiolation specifically in red light. To identify genetic loci necessary for phytochrome signal transduction in red light, we chemically mutagenized ABO seeds and screened M2 seedlings for revertants of the enhanced deetiolation response. One recessive, red light-specific extragenic revertant, designated red1, was isolated. The mutant phenotype was expressed in the original ABO background as well as in the nontransgenic Nossen (No-0) progenitor background. red1 is also deficient in several other aspects of red light-induced responses known to be mediated by phyB, such as inhibition of petiole elongation and the shade avoidance response. red1 was mapped to the bottom of chromosome 4 at a position distinct from all known photoreceptor loci. Together with complementation analysis, the data show that red1 is a novel photomorphogenic mutant. The evidence suggests that red1 represents a putative phytochrome signal transduction mutant potentially specific to the phyB pathway.
Notes:
Wagner, DHoecker, UQuail, P HPlant Cell. 1997 May;9(5):731-43.
TWO SMALL SPATIALLY DISTINCT REGIONS OF PHYTOCHROME B ARE REQUIRED FOR EFFICIENT SIGNALING RATES
Citation:
Wagner, D, Koloszvari M, Quail PH. 1996. Two Small Spatially Distinct Regions of Phytochrome B Are Required for Efficient Signaling Rates, May. The Plant cell. 8:859-871., Number 5
Abstract:
We used a series of in vitro-generated deletion and amino acid substitution derivatives of phytochrome B (phyB) expressed in transgenic Arabidopsis to identify regions of the molecule important for biological activity. Expression of the chromophore-bearing N-terminal domain of phyB alone resulted in a fully photoactive, monomeric molecule lacking normal regulatory activity. Expression of the C-terminal domain alone resulted in a photoinactive, dimeric molecule, also lacking normal activity. Thus, both domains are necessary, but neither is sufficient for phyB activity. Deletion of a small region on each major domain (residues 6 to 57 and 652 to 712, respectively) was shown to compromise phyB activity differentially without interfering with spectral activity or dimerization. Deletion of residues 6 to 57 caused a large increase in the fluence rate of continuous red light (Rc) required for maximal seedling responsiveness, indicating a marked decrease in efficiency of light signal perception or processing per mole of mutant phyB. In contrast, deletion of residues 652 to 712 resulted in a photoreceptor that retained saturation of seedling responsiveness to Rc at low fluence rates but at a response level much below the maximal response elicited by the parent molecule. This deletion apparently reduces the maximal biological activity per mole of phyB without a major decrease in efficiency of signal perception, thus suggesting disruption of a process downstream of signal perception. In addition, certain phyB constructs caused dominant negative interference with endogenous phyA activity in continuous far-red light, suggesting that the two photoreceptors may share reaction partners.
Notes:
Wagner, D.Koloszvari, M.Quail, P. H.Plant Cell. 1996 May;8(5):859-871.
CHROMOPHORE-BEARING NH2-TERMINAL DOMAINS OF PHYTOCHROMES A AND B DETERMINE THEIR PHOTOSENSORY SPECIFICITY AND DIFFERENTIAL LIGHT LABILITY
Citation:
Wagner, D, Fairchild CD, Kuhn RM, Quail PH. 1996. Chromophore-bearing NH2-terminal domains of phytochromes A and B determine their photosensory specificity and differential light lability, Apr 30. Proceedings of the National Academy of Sciences of the United States of America. 93:4011-5., Number 9
Abstract:
In early seedling development, far-red-light-induced deetiolation is mediated primarily by phytochrome A (phyA), whereas red-light-induced deetiolation is mediated primarily by phytochrome B (phyB). To map the molecular determinants responsible for this photosensory specificity, we tested the activities of two reciprocal phyA/phyB chimeras in diagnostic light regimes using overexpression in transgenic Arabidopsis. Although previous data have shown that the NH2-terminal halves of phyA and phyB each separately lack normal activity, fusion of the NH2-terminal half of phyA to the COOH-terminal half of phyB (phyAB) and the reciprocal fusion (phyBA) resulted in biologically active phytochromes. The behavior of these two chimeras in red and far-red light indicates: (i) that the NH2-terminal halves of phyA and phyB determine their respective photosensory specificities; (ii) that the COOH-terminal halves of the two photoreceptors are necessary for regulatory activity but are reciprocally inter-changeable and thus carry functionally equivalent determinants; and (iii) that the NH2-terminal halves of phyA and phyB carry determinants that direct the differential light lability of the two molecules. The present findings suggest that the contrasting photosensory information gathered by phyA and phyB through their NH2-terminal halves may be transduced to downstream signaling components through a common biochemical mechanism involving the regulatory activity of the COOH-terminal domains of the photoreceptors.
Notes:
Wagner, DFairchild, C DKuhn, R MQuail, P HGM47475/GM/NIGMS NIH HHS/Proc Natl Acad Sci U S A. 1996 Apr 30;93(9):4011-5.
MUTATIONAL ANALYSIS OF PHYTOCHROME B IDENTIFIES A SMALL COOH-TERMINAL-DOMAIN REGION CRITICAL FOR REGULATORY ACTIVITY
Citation:
Wagner, D, Quail PH. 1995. Mutational analysis of phytochrome B identifies a small COOH-terminal-domain region critical for regulatory activity, Sep 12. Proceedings of the National Academy of Sciences of the United States of America. 92:8596-600., Number 19
Abstract:
Overexpression of phytochrome B (phyB) in transgenic Arabidopsis results in enhanced deetiolation in red light. To define domains of phyB functionally important for its regulatory activity, we performed chemical mutagenesis of a phyB-overexpressing line and screened for phenotypic revertants in red light. Four phyB-transgene-linked revertants that retain parental levels of full-length, dimeric, and spectrally normal overexpressed phyB were identified among 101 red-light-specific revertants. All carry single amino acid substitutions in the transgene-encoded phyB that reduce activity by 40- to 1000-fold compared to the nonmutagenized parent. The data indicate that the mutant molecules are fully active in photosignal perception but defective in the regulatory activity responsible for signal transfer to downstream components. All four mutations fall within a 62-residue region in the COOH-terminal domain of phyB, with two independent mutations occurring in a single amino acid, Gly-767. Accumulating evidence indicates that the identified region is a critical determinant in the regulatory function of both phyB and phyA.
Notes:
Wagner, DQuail, P HProc Natl Acad Sci U S A. 1995 Sep 12;92(19):8596-600.