Floral organ initiation and development in wild-type Arabidopsis thaliana (Brassicaceae) and in the organ identity mutants apetala2-1 and agamous-1

1994 ◽  
Vol 72 (3) ◽  
pp. 384-401 ◽  
Author(s):  
Wilson Crone ◽  
Elizabeth M. Lord
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Division ◽  
Key Words ◽  
Floral Organ ◽  
Tissue Differentiation ◽  
Main Stem ◽  
Wild Type ◽  
Cell Numbers ◽  
Organ Identity ◽  
Component Cell

The flowers of Arabidopsis thaliana (Brassicaceae) were examined for histological events during organ initiation and later development. An inflorescence floral plastochron of the main stem raceme was used as a basis for the timing and staging of developmental events. Sepals, petals, stamens, and carpels in wild-type Landsberg erecta Arabidopsis are distinguishable as primordia in terms of cell division events associated with initiation, size, and component cell numbers. Flower organogenesis in the organ identity (homeotic) mutants apetala2-1 and agamous-1 was compared with that of the wild type. In both mutants, each whorl of floral organs initiates much like the wild type and only subsequently produces visibly altered organs with mosaic features. The flower organ identity mutants achieve their mature phenotypes by alterations in tissue differentiation that occur after initiation and early primordial development. Key words: Arabidopsis, apetala2-1, agamous-1, plastochron, homeosis, flower.

scholarly journals Nitrate Induction of Primary Root Growth Requires Cytokinin Signaling in Arabidopsis thaliana

2019 ◽  
Vol 61 (2) ◽  
pp. 342-352 ◽  
Author(s):  
Pamela A Naulin ◽  
Grace I Armijo ◽  
Andrea S Vega ◽  
Karem P Tamayo ◽  
Diana E Gras ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Division ◽  
Root Growth ◽  
Primary Root ◽  
Growth Arrest ◽  
Root Tip ◽  
Wild Type ◽  
Cytokinin Signaling ◽  
Control Growth ◽  
Primary Root Growth

Abstract Nitrate can act as a potent signal to control growth and development in plants. In this study, we show that nitrate is able to stimulate primary root growth via increased meristem activity and cytokinin signaling. Cytokinin perception and biosynthesis mutants displayed shorter roots as compared with wild-type plants when grown with nitrate as the only nitrogen source. Histological analysis of the root tip revealed decreased cell division and elongation in the cytokinin receptor double mutant ahk2/ahk4 as compared with wild-type plants under a sufficient nitrate regime. Interestingly, a nitrate-dependent root growth arrest was observed between days 5 and 6 after sowing. Wild-type plants were able to recover from this growth arrest, while cytokinin signaling or biosynthesis mutants were not. Transcriptome analysis revealed significant changes in gene expression after, but not before, this transition in contrasting genotypes and nitrate regimes. We identified genes involved in both cell division and elongation as potentially important for primary root growth in response to nitrate. Our results provide evidence linking nitrate and cytokinin signaling for the control of primary root growth in Arabidopsis thaliana.

Microspore and pollen development in six male-sterile mutants of Arabidopsis thaliana

1993 ◽  
Vol 71 (4) ◽  
pp. 629-638 ◽  
Author(s):  
J. Dawson ◽  
Z. A. Wilson ◽  
M. G. M. Aarts ◽  
A. F. Braithwaite ◽  
L. G. Briarty ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Key Words ◽  
Late Stage ◽  
Pollen Development ◽  
Ethyl Methanesulfonate ◽  
X Rays ◽  
Anther Dehiscence ◽  
Wild Type ◽  
Male Sterile ◽  
Stamen Filament

Five new recessive male-sterile mutants of Arabidopsis thaliana were isolated following seed mutagenesis by X-rays and ethyl methanesulfonate. The cytology of plants homozygous for the msY and msW mutations suggested that pollen development in these lines became abnormal at or before meiosis. The msK mutation caused faulty timing of synthesis or turnover and distribution of callose. In plants homozygous for the msZ mutation, pollen development failed at a late stage. In wild-type plants, the stamen filament elongated just prior to anther dehiscence. In contrast, in the msZ mutant stamen elongation did not occur. Pollen in msH homozygotes was fertile, but anthers failed to dehisce. The msI mutant of J.H. Van der Ween and P. Wirtz (1968. Euphytica 17: 371 – 377) was included in the present study. Pollen development in this mutant failed shortly after microspore release from tetrads. Complementation tests confirmed that the ms mutations were at different loci. Reduced transmission of certain ms genes was observed. Key words: Arabidopsis thaliana, male sterile mutants, anther dehiscence, callose, inheritance.

scholarly journals Mutations in the PERIANTHIA gene of Arabidopsis specifically alter floral organ number and initiation pattern

Development ◽  
1996 ◽  
Vol 122 (4) ◽  
pp. 1261-1269 ◽  
Author(s):  
M.P. Running ◽  
E.M. Meyerowitz
Keyword(s):  
Floral Organ ◽  
Floral Meristem ◽  
Wild Type ◽  
Organ Identity ◽  
The Family ◽  
Dividing Cells ◽  
Meristem Identity ◽  
Plant Families ◽  
Open Question ◽  
Floral Organ Identity Genes

An open question in developmental biology is how groups of dividing cells can generate specific numbers of segments or organs. We describe the phenotypic effects of mutations in PERIANTHIA, a gene specifically required for floral organ patterning in Arabidopsis thaliana. Most wild-type Arabidopsis flowers have 4 sepals, 4 petals, 6 stamens, and 2 carpels. Flowers of perianthia mutant plants most commonly show a pentamerous pattern of 5 sepals, 5 petals 5 stamens, and 2 carpels. This pattern is characteristic of flowers in a number of plant families, but not in the family Brassicaceae, which includes Arabidopsis. Unlike previously described mutations affecting floral organ number, perianthia does not appear to affect apical or floral meristem sizes, nor is any other aspect of vegetative or floral development severely affected. Floral organs in perianthia arise in a regular, stereotypical pattern similar to that in distantly related species with pentamerous flowers. Genetic analysis shows that PERIANTHIA acts downstream of the floral meristem identity genes and independently of the floral meristem size and floral organ identity genes in establishing floral organ initiation patterns. Thus PERIANTHIA acts in a previously unidentified process required for organ patterning in Arabidopsis flowers.

A Mathematical Model of Genetic Control of Determination of Floral Organ Identity in Arabidopsis thaliana

2004 ◽  
Vol 31 (4) ◽  
pp. 346-353 ◽  
Author(s):  
K. G. Skryabin ◽  
D. V. Alekseev ◽  
T. A. Ezhova ◽  
V. N. Kozlov ◽  
V. B. Kudryavtsev ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Arabidopsis Thaliana ◽  
Genetic Control ◽  
Floral Organ ◽  
Floral Organ Identity ◽  
Organ Identity

Induction of "filamentous structures" in wild type Antirrhinum majus flowers by benzylaminopurine

1998 ◽  
Vol 76 (11) ◽  
pp. 1828-1834
Author(s):  
Laureen M Blahut-Beatty ◽  
Peta C Bonham-Smith ◽  
Vipen K Sawhney
Keyword(s):  
Floral Organ ◽  
Distal Portion ◽  
Antirrhinum Majus ◽  
Basal Region ◽  
Wild Type ◽  
Dorsal Region ◽  
Organ Identity ◽  
Specific Factors ◽  
Or Genes ◽  
Floral Organ Identity Genes

The cytokinin, N6-benzylaminopurine (BAP), when applied to young inflorescences of wild-type Antirrhinum majus L., resulted in the formation of chimeric "filamentous structures" in the dorsal region of the third whorl, the position where a stamen primordium is suppressed in wild-type flowers. In addition, BAP induced similar filamentous structures in between the first and second whorls, and this response was concentration dependent. The basal region of the filamentous structures was similar to the filament of a stamen, while the distal portion resembled a petal. These observations suggest that cytokinins may be site-specific factors involved in the regulation of floral organ identity genes or genes that control floral symmetry, i.e., the CYCLOIDEA gene.Key words: Antirrhinum, benzylaminopurine, cytokinin, filament, floral genes, staminode.

scholarly journals SUPERMAN, a regulator of floral homeotic genes in Arabidopsis

Development ◽  
1992 ◽  
Vol 114 (3) ◽  
pp. 599-615 ◽  
Author(s):  
J.L. Bowman ◽  
H. Sakai ◽  
T. Jack ◽  
D. Weigel ◽  
U. Mayer ◽  
...  
Keyword(s):  
Gene Product ◽  
Expression Patterns ◽  
Floral Organ ◽  
Homeotic Genes ◽  
Wild Type ◽  
Floral Homeotic Genes ◽  
Mature Flower ◽  
Organ Identity ◽  
Superman Gene ◽  
Floral Homeotic

We describe a locus, SUPERMAN, mutations in which result in extra stamens developing at the expense of the central carpels in the Arabidopsis thaliana flower. The development of superman flowers, from initial primordium to mature flower, is described by scanning electron microscopy. The development of doubly and triply mutant strains, constructed with superman alleles and previously identified homeotic mutations that cause alterations in floral organ identity, is also described. Essentially additive phenotypes are observed in superman agamous and superman apetala2 double mutants. The epistatic relationships observed between either apetala3 or pistillata and superman alleles suggest that the SUPERMAN gene product could be a regulator of these floral homeotic genes. To test this, the expression patterns of AGAMOUS and APETALA3 were examined in superman flowers. In wild-type flowers, APETALA3 expression is restricted to the second and third whorls where it is required for the specification of petals and stamens. In contrast, in superman flowers, APETALA3 expression expands to include most of the cells that would normally constitute the fourth whorl. This ectopic APETALA3 expression is proposed to be one of the causes of the development of the extra stamens in superman flowers. The spatial pattern of AGAMOUS expression remains unaltered in superman flowers as compared to wild-type flowers. Taken together these data indicate that one of the functions of the wild-type SUPERMAN gene product is to negatively regulate APETALA3 in the fourth whorl of the flower. In addition, superman mutants exhibit a loss of determinacy of the floral meristem, an effect that appears to be mediated by the APETALA3 and PISTILLATA gene products.

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