Control of floral homeotic gene expression and organ morphogenesis in Antirrhinum

Development ◽  
1998 ◽  
Vol 125 (13) ◽  
pp. 2359-2369
Author(s):  
P.C. McSteen ◽  
C.A. Vincent ◽  
S. Doyle ◽  
R. Carpenter ◽  
E.S. Coen
Keyword(s):  
Gene Expression ◽  
Floral Organ ◽  
Reproductive Organs ◽  
Floral Meristem ◽  
Homeotic Gene ◽  
Loss Of Function ◽  
Organ Identity ◽  
Underlying Mechanisms ◽  
Reduced Rate ◽  
Homeotic Gene Expression

The development of reproductive organs in Antirrhinum depends on the expression of an organ identity gene, plena, in the central domain of the floral meristem. To investigate the mechanism by which plena is regulated, we have characterised three mutants in which the pattern of plena expression is altered. In polypetala mutants, expression of plena is greatly reduced, resulting in a proliferation of petals in place of reproductive organs. In addition, polypetala mutants exhibit an altered pattern of floral organ initiation, quite unlike that seen in loss-of-function plena mutants. This suggests that polypetala normally has two roles in flower development: regulation of plena and control of organ primordia formation. In fistulata mutants, plena is ectopically expressed in the distal domain of petal primordia, resulting in the production of anther-like tissue in place of petal lobes. Flowers of fistulata mutants also show a reduced rate of petal lobe growth, even in a plena mutant background. This implies that fistulata normally has two roles in the distal domain of petal primordia: inhibition of plena expression and promotion of lobe growth. A weak allele of the floral meristem identity gene, floricaula, greatly enhances the effect of fistulata on plena expression, showing that floricaula also plays a role in repression of plena in outer whorls. Taken together, these results show that genes involved in plena regulation have additional roles in the formation of organs, perhaps reflecting underlying mechanisms for coupling homeotic gene expression to morphogenesis.

SEUSS, a member of a novel family of plant regulatory proteins, represses floral homeotic gene expression withLEUNIG

Development ◽  
2002 ◽  
Vol 129 (1) ◽  
pp. 253-263 ◽  
Author(s):  
Robert G. Franks ◽  
Chunxin Wang ◽  
Joshua Z. Levin ◽  
Zhongchi Liu
Keyword(s):  
Gene Expression ◽  
Floral Meristem ◽  
Genetic Identification ◽  
Homeotic Gene ◽  
Dimerization Domain ◽  
Homeotic Transformation ◽  
Floral Organs ◽  
Floral Homeotic Gene ◽  
Homeotic Gene Expression ◽  
Floral Homeotic

Proper regulation of homeotic gene expression is critical for pattern formation during both animal and plant development. A negative regulatory mechanism ensures that the floral homeotic gene AGAMOUS is only expressed in the center of an Arabidopsis floral meristem to specify stamen and carpel identity and to repress further proliferation of the floral meristem. We report the genetic identification and characterization of a novel gene, SEUSS, that is required in the negative regulation of AGAMOUS. Mutations in SEUSS cause ectopic and precocious expression of AGAMOUS mRNA, leading to partial homeotic transformation of floral organs in the outer two whorls. The effects of seuss mutations are most striking when combined with mutations in LEUNIG, a previously identified repressor of AGAMOUS. More complete homeotic transformation of floral organs and a greater extent of organ loss in all floral whorls were observed in the seuss leunig double mutants. By in situ hybridization and double and triple mutant analyses, we showed that this enhanced defect was caused by an enhanced ectopic and precocious expression of AGAMOUS. Using a map-based approach, we isolated the SEUSS gene and showed that it encodes a novel protein with at least two glutamine-rich domains and a highly conserved domain that shares sequence identity with the dimerization domain of the LIM-domain-binding transcription co-regulators in animals. Based on these molecular and genetic analyses, we propose that SEUSS encodes a regulator of AGAMOUS and functions together with LEUNIG.

ETTIN patterns the Arabidopsis floral meristem and reproductive organs

Development ◽  
1997 ◽  
Vol 124 (22) ◽  
pp. 4481-4491 ◽  
Author(s):  
A. Sessions ◽  
J.L. Nemhauser ◽  
A. McColl ◽  
J.L. Roe ◽  
K.A. Feldmann ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Double Mutant ◽  
Regional Identity ◽  
Floral Organ ◽  
Reproductive Organs ◽  
Floral Meristem ◽  
Regional Differentiation ◽  
Organ Identity ◽  
Stage 1 ◽  
Floral Meristems

ettin (ett) mutations have pleiotropic effects on Arabidopsis flower development, causing increases in perianth organ number, decreases in stamen number and anther formation, and apical-basal patterning defects in the gynoecium. The ETTIN gene was cloned and encodes a protein with homology to DNA binding proteins which bind to auxin response elements. ETT transcript is expressed throughout stage 1 floral meristems and subsequently resolves to a complex pattern within petal, stamen and carpel primordia. The data suggest that ETT functions to impart regional identity in floral meristems that affects perianth organ number spacing, stamen formation, and regional differentiation in stamens and the gynoecium. During stage 5, ETT expression appears in a ring at the top of the floral meristem before morphological appearance of the gynoecium, consistent with the proposal that ETT is involved in prepatterning apical and basal boundaries in the gynoecium primordium. Double mutant analyses and expression studies show that although ETT transcriptional activation occurs independently of the meristem and organ identity genes LEAFY, APETELA1, APETELA2 and AGAMOUS, the functioning of these genes is necessary for ETT activity. Double mutant analyses also demonstrate that ETT functions independently of the ‘b’ class genes APETELA3 and PISTILLATA. Lastly, double mutant analyses suggest that ETT control of floral organ number acts independently of CLAVATA loci and redundantly with PERIANTHIA.

scholarly journals SET1A/COMPASS and shadow enhancers in the regulation of homeotic gene expression

2017 ◽  
Vol 31 (8) ◽  
pp. 787-801 ◽  
Author(s):  
Kaixiang Cao ◽  
Clayton K. Collings ◽  
Stacy A. Marshall ◽  
Marc A. Morgan ◽  
Emily J. Rendleman ◽  
...  
Keyword(s):  
Gene Expression ◽  
Homeotic Gene ◽  
Homeotic Gene Expression

scholarly journals Pitfall Flower Development and Organ Identity of Ceropegia sandersonii (Apocynaceae-Asclepiadoideae)

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1767
Author(s):  
Annemarie Heiduk ◽  
Dewi Pramanik ◽  
Marlies Spaans ◽  
Loes Gast ◽  
Nemi Dorst ◽  
...  
Keyword(s):  
Gene Expression ◽  
Floral Anatomy ◽  
Floral Organ ◽  
Mads Box ◽  
Floral Organs ◽  
Abcde Model ◽  
Organ Identity ◽  
Mads Box Gene ◽  
Flower Evolution ◽  
Developmental Phases

Deceptive Ceropegia pitfall flowers are an outstanding example of synorganized morphological complexity. Floral organs functionally synergise to trap fly-pollinators inside the fused corolla. Successful pollination requires precise positioning of flies headfirst into cavities at the gynostegium. These cavities are formed by the corona, a specialized organ of corolline and/or staminal origin. The interplay of floral organs to achieve pollination is well studied but their evolutionary origin is still unclear. We aimed to obtain more insight in the homology of the corona and therefore investigated floral anatomy, ontogeny, vascularization, and differential MADS-box gene expression in Ceropegia sandersonii using X-ray microtomography, Light and Scanning Electronic Microscopy, and RT-PCR. During 10 defined developmental phases, the corona appears in phase 7 at the base of the stamens and was not found to be vascularized. A floral reference transcriptome was generated and 14 MADS-box gene homologs, representing all major MADS-box gene classes, were identified. B- and C-class gene expression was found in mature coronas. Our results indicate staminal origin of the corona, and we propose a first ABCDE-model for floral organ identity in Ceropegia to lay the foundation for a better understanding of the molecular background of pitfall flower evolution in Apocynaceae.

Homeotic gene expression in the locustSchistocerca: An antibody that detects conserved epitopes in ultrabithorax and abdominal-A proteins

1994 ◽  
Vol 15 (1) ◽  
pp. 19-31 ◽  
Author(s):  
Robert Kelsh ◽  
Robert O. J. Weinzierl ◽  
Robert A. H. White ◽  
Michael Akam
Keyword(s):  
Gene Expression ◽  
Homeotic Gene ◽  
Homeotic Gene Expression

scholarly journals MADS-box genes are involved in floral development and evolution.

2001 ◽  
Vol 48 (2) ◽  
pp. 351-358 ◽  
Author(s):  
H Saedler ◽  
A Becker ◽  
K U Winter ◽  
C Kirchner ◽  
G Theissen
Keyword(s):  
Floral Development ◽  
Higher Plants ◽  
Control Cell ◽  
Floral Organ ◽  
Reproductive Organs ◽  
Mads Box ◽  
Mads Box Genes ◽  
Flower Bud ◽  
Organ Identity ◽  
Eukaryotic Organisms

MADS-box genes encode transcription factors in all eukaryotic organisms thus far studied. Plant MADS-box proteins contain a DNA-binding (M), an intervening (I), a Keratin-like (K) and a C-terminal C-domain, thus plant MADS-box proteins are of the MIKC type. In higher plants most of the well-characterized genes are involved in floral development. They control the transition from vegetative to generative growth and determine inflorescence meristem identity. They specify floral organ identity as outlined in the ABC model of floral development. Moreover, in Antirrhinum majus the MADS-box gene products DEF/GLO and PLE control cell proliferation in the developing flower bud. In this species the DEF/GLO and the SQUA proteins form a ternary complex which determines the overall "Bauplan" of the flower. Phylogenetic reconstructions of MADS-box sequences obtained from ferns, gymnosperms and higher eudicots reveal that, although ferns possess already MIKC type genes, these are not orthologous to the well characterized MADS-box genes from gymnosperms or angiosperms. Putative orthologs of floral homeotic B- and C-function genes have been identified in different gymnosperms suggesting that these genes evolved some 300-400 million years ago. Both gymnosperms and angiosperms also contain a hitherto unknown sister clade of the B-genes, which we termed Bsister. A novel hypothesis will be described suggesting that B and Bsister might be involved in sex determination of male and female reproductive organs, respectively.

scholarly journals Author response: Deregulated FGF and homeotic gene expression underlies cerebellar vermis hypoplasia in CHARGE syndrome

2013 ◽  
Author(s):  
Tian Yu ◽  
Linda C Meiners ◽  
Katrin Danielsen ◽  
Monica TY Wong ◽  
Timothy Bowler ◽  
...  
Keyword(s):  
Gene Expression ◽  
Charge Syndrome ◽  
Cerebellar Vermis ◽  
Author Response ◽  
Homeotic Gene ◽  
Homeotic Gene Expression

scholarly journals Molecular characterisation of the Polycomblike gene of Drosophila melanogaster, a trans-acting negative regulator of homeotic gene expression

Development ◽  
1994 ◽  
Vol 120 (9) ◽  
pp. 2629-2636 ◽  
Author(s):  
A. Lonie ◽  
R. D'Andrea ◽  
R. Paro ◽  
R. Saint
Keyword(s):  
Gene Expression ◽  
Drosophila Melanogaster ◽  
Polycomb Group ◽  
Negative Regulator ◽  
Homeotic Gene ◽  
Homeotic Genes ◽  
Molecular Characterisation ◽  
Polycomb Group Proteins ◽  
Polycomb Group Genes ◽  
Homeotic Gene Expression

The Polycomblike gene of Drosophila melanogaster, a member of the Polycomb Group of genes, is required for the correct spatial expression of the homeotic genes of the Antennapaedia and Bithorax Complexes. Mutations in Polycomb Group genes result in ectopic homeotic gene expression, indicating that Polycomb Group proteins maintain the transcriptional repression of specific homeotic genes in specific tissues during development. We report here the isolation and molecular characterisation of the Polycomblike gene. The Polycomblike transcript encodes an 857 amino acid protein with no significant homology to other proteins. Antibodies raised against the product of this open reading frame were used to show that the Polycomblike protein is found in all nuclei during embryonic development. Antibody staining also revealed that the Polycomblike protein is found on larval salivary gland polytene chromosomes at about 100 specific loci, the same loci to which the Polycomb and polyhomeotic proteins, two other Polycomb Group proteins, are found. These data add further support for a model in which Polycomb Group proteins form multimeric protein complexes at specific chromosomal loci to repress transcription at those loci.

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