Non-cell-autonomous function of the Antirrhinum floral homeotic proteins DEFICIENS and GLOBOSA is exerted by their polar cell-to-cell trafficking

Development ◽  
1996 ◽  
Vol 122 (11) ◽  
pp. 3433-3441 ◽  
Author(s):  
M.C. Perbal ◽  
G. Haughn ◽  
H. Saedler ◽  
Z. Schwarz-Sommer
Keyword(s):  
Cell Layer ◽  
Epidermal Cells ◽  
Molecular Techniques ◽  
Cell Trafficking ◽  
Mads Box ◽  
Organ Identity ◽  
Cell Layers ◽  
Periclinal Chimeras ◽  
The Difference ◽  
Cell Autonomy

In Antirrhinum majus, petal and stamen organ identity is controlled by two MADS-box transcription factors, DEFICIENS and GLOBOSA. Mutations in either of these genes result in the replacement of petals by sepaloid organs and stamens by carpelloid organs. Somatically stable def and glo periclinal chimeras, generated by transposon excision events, were used to study the non-cell-autonomous functions of these two MADS-box proteins. Two morphologically distinct types of chimeras were analysed using genetic, morphological and molecular techniques. Restoration of DEF expression in the L1 cell layer results in the reestablishment of DEF and GLO functions in L1-derived cells only; inner layer cells retain their mutant sepaloid features. Nevertheless, this activity is sufficient to allow the expansion of petal lobes, highlighting the role of DEF in the stimulation of cell proliferation and/or cell shape and elongation when expressed in the L1 layer. Establishment of DEF or GLO expression in L2 and L3 cell layers is accompanied by the recovery of petaloid identity of the epidermal cells but it is insufficient to allow petal lobe expansion. We show by in situ immunolocalisation that the non-cell-autonomy is due to direct trafficking of DEF and GLO proteins from the inner layer to the epidermal cells. At least for DEF, this movement appears to be polar since DEF acts cell-autonomously when expressed in the L1 cell layer. Furthermore, the petaloid revertant sectors observed on second whorl mutant organs and the mutant margins of petals of L2L3 chimeras suggest that DEF and GLO intradermal movement is limited. This restriction may reflect the difference in the regulation of primary plasmodesmata connecting cells from the same layer and secondary plasmodesmata connecting cells from different layers. We propose that control of intradermal trafficking of DEF and GLO could play a role in maintaining of the boundaries of their expression domains.

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.

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.

scholarly journals Supergene evolution via stepwise duplications and neofunctionalization of a floral-organ identity gene

2020 ◽  
Vol 117 (37) ◽  
pp. 23148-23157 ◽  
Author(s):  
Cuong Nguyen Huu ◽  
Barbara Keller ◽  
Elena Conti ◽  
Christian Kappel ◽  
Michael Lenhard
Keyword(s):  
Pollen Grains ◽  
Floral Organ ◽  
Mads Box ◽  
Style Length ◽  
Insertion Point ◽  
Class Function ◽  
Organ Identity ◽  
Small Pollen ◽  
The Difference ◽  
Insight Into

Heterostyly represents a fascinating adaptation to promote outbreeding in plants that evolved multiple times independently. While l-morph individuals form flowers with long styles, short anthers, and small pollen grains, S-morph individuals have flowers with short styles, long anthers, and large pollen grains. The difference between the morphs is controlled by an S-locus “supergene” consisting of several distinct genes that determine different traits of the syndrome and are held together, because recombination between them is suppressed. In Primula, the S locus is a roughly 300-kb hemizygous region containing five predicted genes. However, with one exception, their roles remain unclear, as does the evolutionary buildup of the S locus. Here we demonstrate that the MADS-box GLOBOSA2 (GLO2) gene at the S locus determines anther position. In Primula forbesii S-morph plants, GLO2 promotes growth by cell expansion in the fused tube of petals and stamen filaments beneath the anther insertion point; by contrast, neither pollen size nor male incompatibility is affected by GLO2 activity. The paralogue GLO1, from which GLO2 arose by duplication, has maintained the ancestral B-class function in specifying petal and stamen identity, indicating that GLO2 underwent neofunctionalization, likely at the level of the encoded protein. Genetic mapping and phylogenetic analysis indicate that the duplications giving rise to the style-length-determining gene CYP734A50 and to GLO2 occurred sequentially, with the CYP734A50 duplication likely the first. Together these results provide the most detailed insight into the assembly of a plant supergene yet and have important implications for the evolution of heterostyly.

scholarly journals Stratification, specialization, and proliferation of primary keratinocyte cultures. Evidence of a functioning in vitro epidermal cell system.

1978 ◽  
Vol 79 (2) ◽  
pp. 356-370 ◽  
Author(s):  
C L Marcelo ◽  
Y G Kim ◽  
J L Kaine ◽  
J J Voorhees
Keyword(s):  
Cell Culture ◽  
Epidermal Cell ◽  
Cell Layer ◽  
Primary Cultures ◽  
Mouse Skin ◽  
Epidermal Cells ◽  
Neonatal Mouse ◽  
Histological Techniques ◽  
Cell Layers ◽  
Epidermal Cell Culture

A population of neonatal mouse keratinocytes (epidermal basal cells) was obtained by gentle, short-term trypsin separation of the epidermal and dermal skin compartments and discontinuous Ficoll gradient purification of the resulting epidermal cells. Over 4--6 wk of culture growth at 32--33 degrees C, the primary cultures formed a complete monolayer that exhibited entire culture stratification and upper cell layer shedding. Transmission and scanning electron microscopy demonstrated that the keratinocyte cultures progressed from one to two cell layers through a series of stratification and specialization phenomena to a six to eight cell layer culture containing structures characteristic of epidermal cells and resembling in vivo epidermal development. The temporal development of primary epidermal cell culture specialization was confirmed by use of two histological techniques which differentially stain the specializing upper cell layers of neonatal mouse skin. No detectable dermal fibroblast co-cultivation was demonstrated by use of the leucine aminopeptidase histochemical technique and routine electron microscope surveillance of the cultures. Incorporation of [3H]thymidine ([3H]Tdr) was greater than 85% into DNA and was inhibited by both 20 micron cytosine arabinoside (Ara-C) and low temperature. Autoradiography and 90% inhibition of [3H]Tdr incorporation by 2 mM hydroxyurea indicated that keratinocyte culture DNA synthesis was scheduled (not a repair phenomenon). The primary keratinocytes showed an oscillating pattern of [3H]Tdr incorporation into DNA over the initial 23--25 days of growth. Autoradiography demonstrated that the cultures contained 10--30% proliferative stem cells from days 2-25 of culture. The reproducibility of both the proliferation and specialization patterns of the described primary epidermal cell culture system indicates that these cultures are a useful tool for investigations of functioning epidermal cell homeostatic control mechanisms.

scholarly journals Petal Cellular Identities

2021 ◽  
Vol 12 ◽  
Author(s):  
Quentin Cavallini-Speisser ◽  
Patrice Morel ◽  
Marie Monniaux
Keyword(s):  
Genetic Basis ◽  
Cell Types ◽  
Epidermal Cells ◽  
Predominant Role ◽  
Main Cell ◽  
Petal Identity ◽  
Organ Identity ◽  
Petal Development ◽  
Cell Layers ◽  
Different Cell Types

Petals are typified by their conical epidermal cells that play a predominant role for the attraction and interaction with pollinators. However, cell identities in the petal can be very diverse, with different cell types in subdomains of the petal, in different cell layers, and depending on their adaxial-abaxial or proximo-distal position in the petal. In this mini-review, we give an overview of the main cell types that can be found in the petal and describe some of their functions. We review what is known about the genetic basis for the establishment of these cellular identities and their possible relation with petal identity and polarity specifiers expressed earlier during petal development, in an attempt to bridge the gap between organ identity and cell identity in the petal.

scholarly journals Mottling on Sweet Cherry Fruit Is Caused by Exocarp Strain

2013 ◽  
Vol 138 (1) ◽  
pp. 18-23 ◽  
Author(s):  
Eckhard Grimm ◽  
Stefanie Peschel ◽  
Moritz Knoche
Keyword(s):  
Surface Area ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Cell Layer ◽  
Epidermal Cells ◽  
Spatial Density ◽  
Spot Area ◽  
Hypodermal Cell ◽  
Cell Layers ◽  
Oriented Parallel

Mottling (pale spots) is clearly visible to the naked eye in all regions of the surface in all except for yellow cultivars of sweet cherry fruit (Prunus avium L.). The objective was to characterize these spots and their distribution on the exocarp. Within the spots, anthocyanins were limited to the epidermal cell layer but, in areas immediately adjacent to the spots, anthocyanins were present in the epidermal and in the hypodermal cell layers (making these areas darker). In ‘Sam’ sweet cherries, the median length and width of a spot in the cheek region were 390 and 162 μm, respectively, and the median area was 0.053 mm2 per spot. The spatial density in the cheek region averaged 1.94 (± 0.13) spots per mm2 and the percentage of surface area covered by the spots was 12.5% (± 1.07%). Epidermal cells within a spot had slightly larger projected surface areas than those in the adjacent region and thicker cell walls. The margins of the spots did not align with the anticlinal walls of the epidermal cells. The spots’ long axes were oriented parallel with the stem/stylar scar axis, whereas the slightly elongated epidermal cells within and adjacent to the spots were orientated perpendicular to the stem/stylar scar axis. The spatial density of spots and the cumulative spot area were highest in the region of the stylar scar, intermediate in the cheek and stem cavity, and lowest in the suture region. Spot spatial density on small fruit exceeded that on larger fruit, but the areas of individual spots was smaller. When an exocarp segment was excised from the cheek of a fruit, it contracted slightly as elastic strain was released. The projected surface area of the spots and that of the whole segment decreased to a similar extent. Our data suggest that spots result from a tensional failure during Stage III development in which the anthocyanin-containing hypodermal cell layer tears (schizogenously) and separates from the epidermis. This being the case, the pale spots (mottling) can be referred to as “strain spots.”

scholarly journals Fluorochrome-coupled lectins reveal distinct cellular domains in human epidermis.

1986 ◽  
Vol 34 (3) ◽  
pp. 307-315 ◽  
Author(s):  
I Virtanen ◽  
A L Kariniemi ◽  
H Holthöfer ◽  
V P Lehto
Keyword(s):  
Endothelial Cells ◽  
Epidermal Cell ◽  
Basal Cell ◽  
Cell Layer ◽  
Lectin Binding ◽  
Epidermal Cells ◽  
Human Epidermis ◽  
Binding Pattern ◽  
Basal Cell Layer ◽  
Cell Layers

The distribution of saccharide moieties in human interfollicular epidermis was studied with fluorochrome-coupled lectins. In frozen sections Concanavalin A (Con A), Lens culinaris agglutinin (LCA), Ricinus communis agglutinin I (RCAI), and wheat germ agglutinin (WGA) stained intensively both dermis and viable epidermal cell layers, whereas peanut agglutinin (PNA) bound only to living epidermal cell layers. Ulex europaeus agglutinin I (UEAI) bound to dermal endothelial cells and upper cell layers of the epidermis but left the basal cell layer unstained. Dolichos biflorus agglutinin (DBA) bound only to basal epidermal cells, whereas both soybean agglutinin (SBA) and Helix pomatia agglutinin (HPA) showed strong binding to the spinous and granular cell layers. On routinely processed paraffin sections, a distinctly different staining pattern was seen with many lectins, and to reveal the binding of some lectins a pretreatment with protease was required. All keratin-positive cells in human epidermal cell suspensions, obtained with the suction blister method, bound PNA, whereas only a fraction of the keratinocytes bound either DBA or UEAI. Such a difference in lectin binding pattern was also seen in epidermal cell cultures both immediately after attachment and in organized cell colonies. This suggests that in addition to basal cells, more differentiated epidermal cells from the spinous cell layer are also able to adhere and spread in culture conditions. Gel electrophoretic analysis of the lectin-binding glycoproteins in detergent extracts of metabolically labeled primary keratinocyte cultures revealed that the lectins recognized both distinct and shared glycoproteins. A much different lectin binding pattern was seen in embryonic human skin: fetal epidermis did not show any binding of DBA, whereas UEAI showed diffuse binding to all cell layers but gave a bright staining of dermal endothelial cells. This was in contrast to staining results obtained with a monoclonal cytokeratin antibody, which showed the presence of a distinct basal cell layer in fetal epidermis also. The results indicate that expression of saccharide moieties in human epidermal keratinocytes is related to the stage of cellular differentiation, different cell layers expressing different terminal saccharide moieties. The results also suggest that the emergence of a mature cell surface glycoconjugate pattern in human epidermis is preceded by the acquisition of cell layer-specific, differential keratin expression.

Penetration and growth of compatible and incompatible races of Phytophthora megasperma var. sojae in soybean hypocotyl tissues differing in age

1980 ◽  
Vol 58 (24) ◽  
pp. 2594-2601 ◽  
Author(s):  
P. Stössel ◽  
G. Lazarovits ◽  
E. W. B. Ward
Keyword(s):  
Glycine Max ◽  
Epidermal Cells ◽  
Mechanisms Of Resistance ◽  
Hypocotyl Growth ◽  
Phytophthora Megasperma ◽  
Cell Layers ◽  
Glycine Max L ◽  
Incompatible Reaction ◽  
Race 4 ◽  
Incompatible Interactions

Intact 6-day old soybean hypocotyls (Glycine max L., cv. Altona) were inoculated with zoospores of Phytophthora megasperma Drechs. var. sojae Hildeb. either at the top (susceptible to compatible races, resistant to incompatible races) or the bottom (resistant to both compatible and incompatible races) and, after a 22-h incubation, were examined by light microscopy. Penetration at the top and bottom by both compatible (race 6) and incompatible (race 4) P. megasperma var. sojae was predominantly between anticlinal walls of epidermal cells. Both races, but especially race 4, also penetrated directly into the outer walls of epidermal cells, but epidermal cells rarely were invaded. Both races grew mainly intercellularly, but race 6 produced haustoria more frequently than race 4. Race 6 haustoria at the top of the hypocotyl were usually encased, those of race 4 were not. Growth of both races was equally dense in the first few cell layers, but the numbers of race 4 hyphae decreased rapidly while those of race 6 became more abundant in the deeper layers. With race 4, but not with race 6, most cells in the infected tissue were necrotic. Differences between the compatible and the incompatible interactions were not absolute; there were many unsuccessful invasion attempts by race 6 and individual hyphae of race 4 spread deeply into the tissue. At the bottom of the hypocotyl, growth of both races was more restricted. Race 6 produced fewer haustoria than at the top, and similarities to the incompatible reaction with race 4 at the top suggest that similar mechanisms of resistance may be involved.

The Synthesis and Migration of Nuclear Proteins during Mitosis and differentiation of Cells in Rats

1965 ◽  
Vol s3-106 (75) ◽  
pp. 229-240
Author(s):  
R. T. SIMS
Keyword(s):  
Granular Cell ◽  
Nuclear Proteins ◽  
Photographic Emulsion ◽  
Metaphase Chromosomes ◽  
Interphase Nuclei ◽  
Cell Layers ◽  
The Difference ◽  
Mitotic Figures ◽  
And Migration ◽  
Silver Grains

Hooded rats were given an intraperitoneal injection of 3H-tyrosine, and killed in pairs 10 min, 30 min, 12 h, 36 h, 7 days, and 30 days later. A piece of skin with white growing hair, and the tongue, were taken from each animal and radioautographs were prepared. Silver grains were counted over whole nuclei and whole mitotic figures of the germinal cells and whole nuclei of differentiating cells of both tissues. It was found that the interphase nuclei have significantly more silver grains over them than the chromosomes at all stages of mitosis and there are virtually no grains over metaphase, anaphase, and early telophase chromosomes in both tissues of all the animals killed up to 36 h after the injection. The difference between the grain counts over the interphase nuclei and the chromosomes of dividing cells is at least 20-fold at 30 min in the hair matrix, at least 5-fold at 30 min in the tongue and at 36 h in both tissues. It was established that the differences observed between the radioactivities of the nuclei and chromosomes of mitotic figures are real from estimates of: the radioactivity of the cell cytoplasm, volumes of the metaphase chromosomes and interphase nuclei within 1µ of the photographic emulsion, and the volumes of cytoplasm separating the photographic emulsion and these structures. No protein synthesis was demonstrable in the chromosomes during metaphase, anaphase, and early telophase. Nuclear proteins leave the chromosomes during prophase and prometaphase and return to the nucleus during late telophase. The cells in the matrix and upper bulb of the growing hair follicle and those in the germinal, prickle, and granular cell layers of the tongue are in different functional states; 30 min after injection of 3H-tyrosine they have different amounts of it in their nuclear proteins. It is suggested that the amount incorporated into each nucleus is related to the rate at which proteins are being synthesized by the cell.

scholarly journals The Orchid MADS-Box Genes Controlling Floral Morphogenesis

2006 ◽  
Vol 6 ◽  
pp. 1933-1944 ◽  
Author(s):  
Wen-Chieh Tsai ◽  
Hong-Hwa Chen
Keyword(s):  
Floral Organ ◽  
Mads Box ◽  
Mads Box Genes ◽  
Floral Diversity ◽  
Physiological Properties ◽  
Abcde Model ◽  
New Variant ◽  
Organ Identity ◽  
Genes Encoding ◽  
Highly Evolved

Orchids are known for both their floral diversity and ecological strategies. The versatility and specialization in orchid floral morphology, structure, and physiological properties have fascinated botanists for centuries. In floral studies, MADS-box genes contributing to the now famous ABCDE model of floral organ identity control have dominated conceptual thinking. The sophisticated orchid floral organization offers an opportunity to discover new variant genes and different levels of complexity to the ABCDE model. Recently, several remarkable research studies done on orchid MADS-box genes have revealed the important roles on orchid floral development. Knowledge about MADS-box genes’' encoding ABCDE functions in orchids will give insights into the highly evolved floral morphogenetic networks of orchids.

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