scholarly journals STYLOSA and FISTULATA: regulatory components of the homeotic control of Antirrhinum floral organogenesis

Development ◽  
1998 ◽  
Vol 125 (1) ◽  
pp. 71-84 ◽  
Author(s):  
P. Motte ◽  
H. Saedler ◽  
Z. Schwarz-Sommer
Keyword(s):  
Ectopic Expression ◽  
Reproductive Organs ◽  
Negative Control ◽  
Homeotic Genes ◽  
Expression Domain ◽  
Floral Organogenesis ◽  
Organ Identity ◽  
Class B ◽  
Spatial Differences ◽  
Meristem Identity

The identity and developmental pattern of the four organ types constituting the flower is governed by three developmental functions, A, B and C, which are defined by homeotic genes and established in two adjacent whorls. In this report we morphologically and genetically characterise mutants of two genes, STYLOSA (STY) and FISTULATA (FIS) which control floral homeotic meristem- and organ-identity genes and developmental events in all floral whorls. The morphology of the reproductive organs in the first and second whorls of sty fis double mutant flowers indicate that the two genes are part of the mechanism to prevent ectopic expression of the C-function in the perianth of wild-type flowers. This is verified by the detection of the expansion of the expression domain of the class C gene PLENA (PLE) towards the perianth. Interestingly, in the second whorl of sty and fis mutants, spatial differences in stamenoid features and in the pattern of ectopic expression of the PLE gene were observed. This suggests that, with respect to the negative control of PLE, petals are composed of two regions, a lateral and a central one. Mutation in ple is epistatic to most of the sty/fis-related homeotic defects. PLE, however, is not the primary target of STY/FIS control, because dramatic reduction of expression of FIMBRIATA, meristem identity genes (FLORICAULA and SQUAMOSA) and of class B organ identity genes (GLOBOSA) occur before changes in the PLE expression pattern. We propose that STY/FIS are hierarchically high-ranking genes that control cadastral component(s) of the A-function. SQUAMOSA as a potential target of this control is discussed. Retarded growth of second whorl organs, subdivision of third whorl primordia and the failure to initiate them in sty/fis mutants may be mediated by the FIMBRIATA gene.

Expression of floricaula in single cell layers of periclinal chimeras activates downstream homeotic genes in all layers of floral meristems

Development ◽  
1995 ◽  
Vol 121 (1) ◽  
pp. 27-35 ◽  
Author(s):  
S.S. Hantke ◽  
R. Carpenter ◽  
E.S. Coen
Keyword(s):  
Cell Layer ◽  
Homeotic Genes ◽  
Expression Domain ◽  
Phenotypic Properties ◽  
Organ Identity ◽  
Cell Layers ◽  
Periclinal Chimeras ◽  
Meristem Identity ◽  
Cell Autonomy ◽  
Floral Meristems

We show that the flowering sectors on plants mutant for floricaula (flo), a meristem identity gene in Antirrhinum majus, are periclinal chimeras expressing flo in either the L1, L2 or L3 cell layer. Flower morphology is almost normal in L1 chimeras, but altered in L2 and L3 chimeras. Expression of flo in any one cell layer results in the expression of organ identity genes, deficiens (def) and plena (ple) in all three cell layers of the chimeras, showing that flo acts inductively to promote gene transcription. The activation of both def and ple is delayed, and the expression domain of def is reduced, accounting for some of the phenotypic properties of the chimeras. Furthermore, we show that flo exhibits some cell-autonomy with respect to autoregulation.

scholarly journals Epidermal control of floral organ identity by class B homeotic genes in Antirrhinum and Arabidopsis

Development ◽  
2001 ◽  
Vol 128 (14) ◽  
pp. 2661-2671
Author(s):  
Nadia Efremova ◽  
Marie-Christine Perbal ◽  
Alexander Yephremov ◽  
Winfried A. Hofmann ◽  
Heinz Saedler ◽  
...  
Keyword(s):  
Transgene Expression ◽  
Transgenic Arabidopsis ◽  
Cell Communication ◽  
Cell Types ◽  
Floral Organ ◽  
Epidermal Differentiation ◽  
Homeotic Genes ◽  
Organ Identity ◽  
Class B ◽  
Functional Homologues

To assess the contribution of the epidermis to the control of petal and stamen organ identity, we have used transgenic Antirrhinum and Arabidopsis plants that expressed the Antirrhinum class B homeotic transcription factors DEFICIENS (DEF) and GLOBOSA (GLO) in the epidermis. Transgene expression was controlled by the ANTIRRHINUM FIDDLEHEAD (AFI) promoter, which directs gene expression to the L1 meristematic layer and, later, to the epidermis of differentiating organs. Transgenic epidermal DEF and GLO chimeras display similar phenotypes, suggesting similar epidermal contributions by the two class B genes in Antirrhinum. Epidermal B function autonomously controls the differentiation of Antirrhinum petal epidermal cell types, but cannot fully control the pattern of cell divisions and the specification of sub-epidermal petal cell-identity by epidermal signalling. This non-autonomous control is enhanced if the endogenous class B genes can be activated from the epidermis. The developmental influence of epidermal B function in Antirrhinum stamen development is very limited. In contrast, epidermal B function in Arabidopsis can control most if not all epidermal and sub-epidermal differentiation events in petals and stamens, without any contribution from the endogenous class B genes. Possible reasons for differences in the efficacy of B-function-mediated cell communication between the two species are discussed. Interestingly, our experiments uncovered partial incompatibility between class B functional homologues. Although the DEFICIENS/PISTILLATA heterodimer is functional in transgenic Arabidopsis plants, the APETALA3/GLOBOSA heterodimer is not.

scholarly journals AINTEGUMENTA and AINTEGUMENTA-LIKE6 directly regulate floral homeotic and growth genes in young flowers

2020 ◽  
Author(s):  
Beth A. Krizek ◽  
Alexis T. Bantle ◽  
Jorman M. Heflin ◽  
Han Han ◽  
Nowlan H. Freese ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Binding Sites ◽  
Floral Organ ◽  
Homeotic Genes ◽  
Flower Primordia ◽  
Floral Organ Identity ◽  
Floral Organogenesis ◽  
Floral Homeotic Genes ◽  
Organ Identity ◽  
Floral Homeotic

AbstractArabidopsis flower primordia give rise to floral organ primordia in stereotypical positions within four concentric whorls. Floral organ primordia in each whorl undergo distinct developmental programs to become one of four organ types (sepals, petals, stamens, and carpels). The Arabidopsis transcription factors AINTEGUMENTA (ANT) and AINTEGUMENTA-LIKE6 (AIL6) play critical and partially overlapping roles during floral organogenesis. They are required for correct positioning of floral organ initiation, contribute to the specification of floral organ identity, and regulate the growth and morphogenesis of developing floral organs. To gain insight into the molecular means by which ANT and AIL6 contribute to floral organogenesis, we identified the genome-wide binding sites of both ANT and AIL6 in stage 3 flower primordia, the developmental stage at which sepal primordia become visible and class B and C floral homeotic genes are first expressed. AIL6 binds to a subset of ANT sites, suggesting that AIL6 regulates some but not all of the same target genes as ANT. ANT and AIL6 binding sites are associated with genes involved in many biological processes related to meristem and flower organ development. Comparison of genes associated with both ANT and AIL6 ChIP-Seq peaks and those differentially expressed after perturbation of ANT or AIL6 activity identified likely direct targets of ANT and AIL6 regulation. These include the floral homeotic genes APETALA3 (AP3) and AGAMOUS (AG) and four growth regulatory genes: BIG BROTHER (BB), ROTUNDIFOLIA3 (ROT3), ANGUSTIFOLIA3/GRF INTERACTING FACTOR (AN3/GIF1), and XYLOGLUCAN ENDOTRANSGLUCOLSYLASE/HYDROLASE9 (XTH9).One Sentence SummaryThe transcription factors ANT and AIL6 directly regulate genes involved in different aspects of flower development including genes that specify floral organ identity and those that regulate growth.

scholarly journals The Arabidopsis homeotic genes APETALA3 and PISTILLATA are sufficient to provide the B class organ identity function

Development ◽  
1996 ◽  
Vol 122 (1) ◽  
pp. 11-22 ◽  
Author(s):  
B.A. Krizek ◽  
E.M. Meyerowitz
Keyword(s):  
Mosaic Virus ◽  
Cauliflower Mosaic Virus ◽  
35S Promoter ◽  
Homeotic Genes ◽  
Identity Function ◽  
Leaf Curling ◽  
Class A ◽  
Organ Identity ◽  
Class B ◽  
Additional Role

The class B organ identity genes, APETALA3 and PISTILLATA, are required to specify petal and stamen identity in the Arabidopsis flower. We show here that the activities of these two genes are sufficient to specify petals and stamens in flowers, in combination with the class A and C genes, respectively. Flowers of plants constitutively expressing both PISTILLATA and APETALA3 under the control of the 35S promoter from cauliflower mosaic virus consist of two outer whorls of petals and inner whorls of stamens. These plants also exhibit vegetative phenotypes that are not present in either of the singly (APETALA3 or PISTILLATA) overexpressing lines. These phenotypes include leaf curling and the partial conversion of later-arising cauline leaves to petals. The presence of additional floral whorls in flowers ectopically expressing APETALA3 and PISTILLATA and the rescue of missing organs in class A mutants by ectopic B function suggest that APETALA3 and PISTILLATA play an additional role in proliferation of the floral meristem.

OsMADS32 Regulates Rice Floral Patterning through Interactions with Multiple Floral Homeotic Genes

2020 ◽  
Author(s):  
Yun Hu ◽  
Li Wang ◽  
Ru Jia ◽  
Wanqi Liang ◽  
Xuelian Zhang ◽  
...  
Keyword(s):  
Flower Development ◽  
Floral Organ ◽  
Floral Meristem ◽  
Homeotic Genes ◽  
Dependent Manner ◽  
Floral Meristem Identity ◽  
Floral Homeotic Genes ◽  
Organ Identity ◽  
Meristem Identity ◽  
Floral Homeotic

Abstract Floral patterning is regulated by intricate networks of floral identity genes. The peculiar MADS32 subfamily genes, absent in eudicots but prevalent in monocots, regulate floral organ identity. However, how the MADS32 family genes interact with other floral homeotic genes during flower development is mostly unknown. We show here that the rice homeotic transcription factor OsMADS32 regulates floral patterning by interacting synergistically with E class protein OsMADS6 in a dosage-dependent manner. Furthermore, our results indicate important roles of OsMADS32 in defining stamen, pistil and ovule development through physical and genetic interactions with OsMADS1, OsMADS58 and OsMADS13, and in specifying floral meristem identity with OsMADS6, OsMADS3 and OsMADS58 respectively. Our findings suggest that OsMADS32 is an important factor for floral meristem identity maintenance and that it integrates the action of other MADS-box homeotic proteins to sustain floral organ specification and development in rice. Given that OsMADS32 is an orphan gene and absent in eudicots, our data substantially expand our understanding of flower development in plants.

scholarly journals Genetic and Molecular Control of Floral Organ Identity in Cereals

2019 ◽  
Vol 20 (11) ◽  
pp. 2743 ◽  
Author(s):  
Zulfiqar Ali ◽  
Qasim Raza ◽  
Rana Muhammad Atif ◽  
Usman Aslam ◽  
Muhammad Ajmal ◽  
...  
Keyword(s):  
Morphological Diversity ◽  
Floral Organ ◽  
Homeotic Genes ◽  
Inflorescence Development ◽  
Yield Improvement ◽  
Molecular Control ◽  
Floral Organ Identity ◽  
Floral Organogenesis ◽  
Partial Conservation ◽  
Organ Identity

Grasses represent a major family of monocots comprising mostly cereals. When compared to their eudicot counterparts, cereals show a remarkable morphological diversity. Understanding the molecular basis of floral organ identity and inflorescence development is crucial to gain insight into the grain development for yield improvement purposes in cereals, however, the exact genetic mechanism of floral organogenesis remains elusive due to their complex inflorescence architecture. Extensive molecular analyses of Arabidopsis and other plant genera and species have established the ABCDE floral organ identity model. According to this model, hierarchical combinatorial activities of A, B, C, D, and E classes of homeotic genes regulate the identity of different floral organs with partial conservation and partial diversification between eudicots and cereals. Here, we review the developmental role of A, B, C, D, and E gene classes and explore the recent advances in understanding the floral development and subsequent organ specification in major cereals with reference to model plants. Furthermore, we discuss the evolutionary relationships among known floral organ identity genes. This comparative overview of floral developmental genes and associated regulatory factors, within and between species, will provide a thorough understanding of underlying complex genetic and molecular control of flower development and floral organ identity, which can be helpful to devise innovative strategies for grain yield improvement in cereals.

Regulation of cell proliferation patterns by homeotic genes during Arabidopsis floral development

Development ◽  
2000 ◽  
Vol 127 (6) ◽  
pp. 1267-1276 ◽  
Author(s):  
P.D. Jenik ◽  
V.F. Irish
Keyword(s):  
Cell Proliferation ◽  
Apical Meristem ◽  
Floral Development ◽  
Developmental Process ◽  
Cell Layer ◽  
Homeotic Genes ◽  
Transmitting Tract ◽  
Organ Identity ◽  
Element System ◽  
Cell Layers

The shoot apical meristem of Arabidopsis thaliana consists of three cell layers that proliferate to give rise to the aerial organs of the plant. By labeling cells in each layer using an Ac-based transposable element system, we mapped their contributions to the floral organs, as well as determined the degree of plasticity in this developmental process. We found that each cell layer proliferates to give rise to predictable derivatives: the L1 contributes to the epidermis, the stigma, part of the transmitting tract and the integument of the ovules, while the L2 and L3 contribute, to different degrees, to the mesophyll and other internal tissues. In order to test the roles of the floral homeotic genes in regulating these patterns of cell proliferation, we carried out similar clonal analyses in apetala3-3 and agamous-1 mutant plants. Our results suggest that cell division patterns are regulated differently at different stages of floral development. In early floral stages, the pattern of cell divisions is dependent on position in the floral meristem, and not on future organ identity. Later, during organogenesis, the layer contributions to the organs are controlled by the homeotic genes. We also show that AGAMOUS is required to maintain the layered structure of the meristem prior to organ initiation, as well as having a non-autonomous role in the regulation of the layer contributions to the petals.

Ectopic expression of homeotic genes caused by the elimination of the Polycomb gene in Drosophila imaginal epidermis

Development ◽  
1988 ◽  
Vol 104 (4) ◽  
pp. 713-720 ◽  
Author(s):  
A. Busturia ◽  
G. Morata
Keyword(s):  
Ectopic Expression ◽  
Homeotic Genes ◽  
Sex Combs Reduced ◽  
Hierarchical Order ◽  
Sex Combs ◽  
Morphological Patterns

The morphological patterns in the adult cuticle of Drosophila are determined principally by the homeotic genes of the bithorax and Antennapedia complexes. We find that many of these genes become indiscriminately active in the adult epidermis when the Pc gene is eliminated. By using the Pc3 mutation and various BX-C mutant combinations, we have generated clones of imaginal cells possessing different combinations of active homeotic genes. We find that, in the absence of BX-C genes, Pc- clones develop prothoracic patterns; this is probably due to the activity of Sex combs reduced which overrules Antennapedia. Adding contributions of Ultrabithorax, abdominal-A and Abdominal-B results in thoracic or abdominal patterns. We have established a hierarchical order among these genes: Antp less than Scr less than Ubx less than abd-A less than Abd-B. In addition, we show that the engrailed gene is ectopically active in Pc- imaginal cells.

pha-4 is Ce-fkh-1, a fork head/HNF-3alpha, beta, gamma homolog that functions in organogenesis of the C. elegans pharynx

Development ◽  
1998 ◽  
Vol 125 (12) ◽  
pp. 2171-2180 ◽  
Author(s):  
J.M. Kalb ◽  
K.K. Lau ◽  
B. Goszczynski ◽  
T. Fukushige ◽  
D. Moons ◽  
...  
Keyword(s):  
Early Stage ◽  
Sequence Similarity ◽  
Expression Patterns ◽  
Ectopic Expression ◽  
Specific Gene ◽  
Gata Factor ◽  
Enhancer Element ◽  
C Elegans ◽  
Fork Head ◽  
Organ Identity

The C. elegans Ce-fkh-1 gene has been cloned on the basis of its sequence similarity to the winged-helix DNA binding domain of the Drosophila fork head and mammalian HNF-3alpha, beta, gamma genes, and mutations in the zygotically active pha-4 gene have been shown to block formation of the pharynx (and rectum) at an early stage in embryogenesis. In the present paper, we show that Ce-fkh-1 and pha-4 are the same gene. We show that PHA-4 protein is present in nuclei of essentially all pharyngeal cells, of all five cell types. PHA-4 protein first appears close to the point at which a cell lineage will produce only pharyngeal cells, independently of cell type. We show that PHA-4 binds directly to a ‘pan-pharyngeal enhancer element’ previously identified in the promoter of the pharyngeal myosin myo-2 gene; in transgenic embryos, ectopic PHA-4 activates ectopic myo-2 expression. We also show that ectopic PHA-4 can activate ectopic expression of the ceh-22 gene, a pharyngeal-specific NK-2-type homeodomain protein previously shown to bind a muscle-specific enhancer near the PHA-4 binding site in the myo-2 promoter. We propose that it is the combination of pha-4 and regulatory molecules such as ceh-22 that produces the specific gene expression patterns during pharynx development. Overall, pha-4 can be described as an ‘organ identity factor’, completely necessary for organ formation, present in all cells of the organ from the earliest stages, capable of integrating upstream developmental pathways (in this case, the two distinct pathways that produce the anterior and posterior pharynx) and participating directly in the transcriptional regulation of organ specific genes. Finally, we note that the distribution of PHA-4 protein in C. elegans embryos is remarkably similar to the distribution of the fork head protein in Drosophila embryos: high levels in the foregut/pharynx and hindgut/rectum; low levels in the gut proper. Moreover, we show that pha-4 expression in the C. elegans gut is regulated by elt-2, a C. elegans gut-specific GATA-factor and possible homolog of the Drosophila gene serpent, which influences fork head expression in the fly gut. Overall, our results provide evidence for a highly conserved pathway regulating formation of the digestive tract in all (triploblastic) metazoa.

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