scholarly journals Quantitative live-imaging of Aquilegia floral meristems reveals distinct patterns of floral organ initiation and cell-level dynamics of floral meristem termination

2021 ◽  
Author(s):  
Ya Min ◽  
Stephanie J. Conway ◽  
Elena M. Kramer
Keyword(s):  
Cell Division ◽  
Floral Organ ◽  
Live Imaging ◽  
Confocal Imaging ◽  
Floral Meristem ◽  
Flowering Plant ◽  
Molecular Networks ◽  
Floral Organs ◽  
Meristem Development ◽  
Floral Meristems

ABSTRACTIn-depth investigation of any developmental process in plants requires knowledge of both the underpinning molecular networks and how they directly determine patterns of cell division and expansion over time. Floral meristems (FM) produce floral organs, after which they undergo floral meristem termination (FMT), and precise control of organ initiation and FMT is crucial to reproductive success of any flowering plant. Using a live confocal imaging, we characterized developmental dynamics during floral organ primordia initiation and FMT in Aquilegia coerulea (Ranunculaceae). Our results have uncovered distinct patterns of primordium initiation between stamens and staminodes compared to carpels, and provided insight into the process of FMT, which is discernable based on cell division dynamics preceding carpel initiation. To our knowledge, this is the first quantitative live imaging of meristem development in a system with numerous whorls of floral organs as well as an apocarpous gynoecium. This study provides crucial information for our understanding of how the spatial-temporal regulation of floral meristem behavior is achieved in both an evolutionary and developmental context.

scholarly journals The CLAVATA and SHOOT MERISTEMLESS loci competitively regulate meristem activity in Arabidopsis

Development ◽  
1996 ◽  
Vol 122 (5) ◽  
pp. 1567-1575 ◽  
Author(s):  
S.E. Clark ◽  
S.E. Jacobsen ◽  
J.Z. Levin ◽  
E.M. Meyerowitz
Keyword(s):  
Cell Division ◽  
Cell Differentiation ◽  
Embryonic Development ◽  
Genetic Interactions ◽  
Floral Meristem ◽  
Shoot Meristem ◽  
Meristem Development ◽  
Undifferentiated Cells ◽  
Floral Meristems ◽  
Shoot Meristemless

The CLAVATA (CLV1 and CLV3) and SHOOT MERISTEMLESS (STM) genes specifically regulate shoot meristem development in Arabidopsis. CLV and STH appear to have opposite functions: c1v1 and Clv3 mutants accumulate excess undifferentiated cells in the shoot and floral meristem, while stm mutants fail to form the undifferentiated cells of the shoot meristem during embryonic development. We have identified a weak allele of stm (stm-2) that reveals STM is not only required for the establish- ment of the shoot meristem, but is also required for the continued maintenance of undifferentiated cells in the shoot meristem and for proper proliferation of cells in the floral meristem. We have found evidence of genetic interactions between the CLV and STM loci. clv1 and c1v3 mutations partially suppressed the stm-1 and stm-2 phenotypes, and were capable of suppression in a dominant fashion. clv stm double mutants and plants homozygous for stm but heterozygous for clv, while still lacking an embryonic shoot meristem, exhibited greatly enhanced postembryonic shoot and floral meristem development. Although stm phenotypes are recessive, stm mutations dominantly suppressed clv homozygous and heterozygous phenotypes. These results indicate that the stm phenotype is sensitive to the levels of CLV activity, while the clv phenotype is sensitive to the level of STM activity. We propose that these genes play related but opposing roles in the regulation of cell division and/or cell differentiation in shoot and floral meristems.

scholarly journals Then There Were Plenty-Ring Meristems Giving Rise to Many Stamen Whorls

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1140
Author(s):  
Doudou Kong ◽  
Annette Becker
Keyword(s):  
Arabidopsis Thaliana ◽  
Dynamic Systems ◽  
Molecular Genetic ◽  
Floral Organ ◽  
Fixed Number ◽  
Floral Meristem ◽  
Ecological Value ◽  
Genetic Studies ◽  
Stamen Primordia ◽  
Floral Meristems

Floral meristems are dynamic systems that generate floral organ primordia at their flanks and, in most species, terminate while giving rise to the gynoecium primordia. However, we find species with floral meristems that generate additional ring meristems repeatedly throughout angiosperm history. Ring meristems produce only stamen primordia, resulting in polystemous flowers (having stamen numbers more than double that of petals or sepals), and act independently of the floral meristem activity. Most of our knowledge on floral meristem regulation is derived from molecular genetic studies of Arabidopsis thaliana, a species with a fixed number of floral organs and, as such of only limited value for understanding ring meristem function, regulation, and ecological value. This review provides an overview of the main molecular players regulating floral meristem activity in A. thaliana and summarizes our knowledge of ring primordia morphology and occurrence in dicots. Our work provides a first step toward understanding the significance and molecular genetics of ring meristem regulation and evolution.

scholarly journals Expression of KNUCKLES in the Stem Cell Domain Is Required for Its Function in the Control of Floral Meristem Activity in Arabidopsis

2021 ◽  
Vol 12 ◽  
Author(s):  
Kamila Kwaśniewska ◽  
Caoilfhionn Breathnach ◽  
Christina Fitzsimons ◽  
Kevin Goslin ◽  
Bennett Thomson ◽  
...  
Keyword(s):  
Stem Cell ◽  
Regulatory Gene ◽  
Cell Activity ◽  
Floral Organ ◽  
Floral Meristem ◽  
Perturbation Approach ◽  
Expression Domain ◽  
Organ Identity ◽  
Early Expression ◽  
Floral Meristems

In the model plant Arabidopsis thaliana, the zinc-finger transcription factor KNUCKLES (KNU) plays an important role in the termination of floral meristem activity, a process that is crucial for preventing the overgrowth of flowers. The KNU gene is activated in floral meristems by the floral organ identity factor AGAMOUS (AG), and it has been shown that both AG and KNU act in floral meristem control by directly repressing the stem cell regulator WUSCHEL (WUS), which leads to a loss of stem cell activity. When we re-examined the expression pattern of KNU in floral meristems, we found that KNU is expressed throughout the center of floral meristems, which includes, but is considerably broader than the WUS expression domain. We therefore hypothesized that KNU may have additional functions in the control of floral meristem activity. To test this, we employed a gene perturbation approach and knocked down KNU activity at different times and in different domains of the floral meristem. In these experiments we found that early expression in the stem cell domain, which is characterized by the expression of the key meristem regulatory gene CLAVATA3 (CLV3), is crucial for the establishment of KNU expression. The results of additional genetic and molecular analyses suggest that KNU represses floral meristem activity to a large extent by acting on CLV3. Thus, KNU might need to suppress the expression of several meristem regulators to terminate floral meristem activity efficiently.

scholarly journals CLAVATA3 is a specific regulator of shoot and floral meristem development affecting the same processes as CLAVATA1

Development ◽  
1995 ◽  
Vol 121 (7) ◽  
pp. 2057-2067 ◽  
Author(s):  
S. E. Clark ◽  
M. P. Running ◽  
E. M. Meyerowitz
Keyword(s):  
Arabidopsis Thaliana ◽  
Flower Development ◽  
Mature Embryo ◽  
Floral Meristem ◽  
Wild Type ◽  
Apical Meristems ◽  
Meristem Development ◽  
Embryo Stage ◽  
Double Heterozygosity ◽  
Floral Meristems

We have previously described the phenotype of Arabidopsis thaliana plants with mutations at the CLAVATA1 (CLV1) locus (Clark, S. E., Running, M. P. and Meyerowitz, E. M. (1993) Development 119, 397–418). Our investigations demonstrated that clv1 plants develop enlarged vegetative and inflorescence apical meristems, and enlarged and indeterminate floral meristems. Here, we present an analysis of mutations at a separate locus, CLAVATA3 (CLV3), that disrupt meristem development in a manner similar to clv1 mutations. clv3 plants develop enlarged apical meristems as early as the mature embryo stage. clv3 floral meristems are also enlarged compared with wild type, and maintain a proliferating meristem throughout flower development. clv3 root meristems are unaffected, indicating that CLV3 is a specific regulator of shoot and floral meristem development. We demonstrate that the strong clv3-2 mutant is largely epistatic to clv1 mutants, and that the semi- dominance of clv1 alleles is enhanced by double heterozygosity with clv3 alleles, suggesting that these genes work in the same pathway to control meristem development. We propose that CLV1 and CLV3 are required to promote the differentiation of cells at the shoot and floral meristem.

scholarly journals Mutation at the tomato EXCESSIVE NUMBER OF FLORAL ORGANS (ENO) locus impairs floral meristem development, thus promoting an increased number of floral organs and fruit size

Plant Science ◽  
2015 ◽  
Vol 232 ◽  
pp. 41-48 ◽  
Author(s):  
Antonia Fernández-Lozano ◽  
Fernando J. Yuste-Lisbona ◽  
Fernando Pérez-Martín ◽  
Benito Pineda ◽  
Vicente Moreno ◽  
...  
Keyword(s):  
Fruit Size ◽  
Floral Meristem ◽  
Floral Organs ◽  
Meristem Development ◽  
Excessive Number

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 The WIGGUM gene is required for proper regulation of floral meristem size in Arabidopsis

Development ◽  
1998 ◽  
Vol 125 (14) ◽  
pp. 2545-2553 ◽  
Author(s):  
M.P. Running ◽  
J.C. Fletcher ◽  
E.M. Meyerowitz
Keyword(s):  
Cell Division ◽  
Apical Meristem ◽  
Critical Role ◽  
Floral Meristem ◽  
Similar Process ◽  
Genetic Studies ◽  
Meristem Size ◽  
Separate Pathway ◽  
Mutant Phenotypes ◽  
Floral Meristems

The study of cell division control within developing tissues is central to understanding the processes of pattern formation. The floral meristem of angiosperms gives rise to floral organs in a particular number and pattern. Despite its critical role, little is known about how cell division is controlled in the floral meristem, and few genes involved have been identified. We describe the phenotypic effects of mutations in WIGGUM, a gene required for control of cell proliferation in the floral and apical meristem of Arabidopsis thaliana. wiggum flowers contain more organs, especially sepals and petals, than found in wild-type flowers. This organ number phenotype correlates with specific size changes in the early floral meristem, preceding organ initiation. Genetic studies suggest that WIGGUM acts on a similar process but in a separate pathway than the CLAVATA1 and CLAVATA3 genes in meristem size regulation, and reveal interactions with other genes affecting meristem structure and identity. Analysis of double mutant phenotypes also reveals a role for WIGGUM in apical meristem function. We propose that WIGGUM plays a role in restricting cell division relative to cellular differentiation in specific regions of the apical and floral meristems.

scholarly journals Floral Meristem Development in Cranberry Apical Buds during Winter Rest and Its Implication on Yield Prediction

2019 ◽  
Vol 144 (5) ◽  
pp. 314-320
Author(s):  
Jenny L. Bolivar-Medina ◽  
Camilo Villouta ◽  
Beth Ann Workmaster ◽  
Amaya Atucha
Keyword(s):  
Histological Study ◽  
Development Stage ◽  
Fruit Production ◽  
Floral Meristem ◽  
Limited Information ◽  
Apical Buds ◽  
Meristem Development ◽  
Bud Size ◽  
Crop Forecasting ◽  
Floral Meristems

The formation and development of floral meristems is key to fruit production. However, limited information regarding the development of floral buds during the dormant period of cranberry (Vaccinium macrocarpon) constrains the ability to forecast yield early and accurately. The objectives of this study were to characterize the development of floral meristems from fall to spring and to evaluate the number of floral meristems formed across different bud sizes and upright types, as well as their contribution to the fruit production of the next year. Apical buds of different sizes on vegetative and fruiting uprights were tagged and collected periodically from fall to spring for histological study. An extra set of tagged buds was left in the field to evaluate their flower and fruit production. Five stages of floral development were identified based on the concentric differentiation of organ primordia. Large buds from vegetative uprights developed earlier, had a higher number of floral meristems, and became fruiting uprights; they had the highest number of flowers and fruit. Buds from fruiting uprights had the lowest number of floral meristems and delayed development; subsequently, they had the lowest number of fruit per upright. Our results provide evidence of active floral meristem differentiation during fall and winter, as well as differences in the timing and development stage according to bud size. In addition, our study shows that upright types and bud sizes influence the fruit production of the following year; therefore, they should be considered in cranberry crop forecasting models.

scholarly journals TSO1 functions in cell division during Arabidopsis flower development

Development ◽  
1997 ◽  
Vol 124 (3) ◽  
pp. 665-672 ◽  
Author(s):  
Z. Liu ◽  
M.P. Running ◽  
E.M. Meyerowitz
Keyword(s):  
Cell Division ◽  
Flower Development ◽  
Cell Walls ◽  
Dna Ploidy ◽  
Floral Meristem ◽  
Specific Cell ◽  
Floral Organs ◽  
Size And Shape ◽  
Cell Layers ◽  
Arabidopsis Mutant

We describe an Arabidopsis mutant, tso1, which develops callus-like tissues in place of floral organs. The tso1 floral meristem lacks properly organized three cell layers, and the nuclei of these cells are irregular in size and shape. Further analyses reveal partially formed cell walls and increased DNA ploidy in tso1 floral meristem cells, indicating defects in mitosis and cytokinesis. Our finding that TSO1 is required for organ formation in floral tissues but not in other tissues indicates that TSO1 may encode a floral-specific cell division component, or that TSO1 function is redundant in nonfloral tissues.

Regulation of meristem organization and cell division by TSO1, an Arabidopsis gene with cysteine-rich repeats

Development ◽  
2000 ◽  
Vol 127 (10) ◽  
pp. 2207-2217 ◽  
Author(s):  
J.Y. Song ◽  
T. Leung ◽  
L.K. Ehler ◽  
C. Wang ◽  
Z. Liu
Keyword(s):  
Cell Division ◽  
Higher Plants ◽  
Floral Meristem ◽  
Higher Plant ◽  
Meristem Cell ◽  
Arabidopsis Gene ◽  
Multinucleated Cells ◽  
Meristem Development

In higher plants, meristem organization and cell division regulation are two fundamentally important and intimately related biological processes. Identifying and isolating regulatory genes in these processes is essential for understanding higher plant growth and development. We describe the molecular isolation and analyses of an Arabidopsis gene, TSO1, which regulates both of these processes. We previously showed that tso1 mutants displayed defects in cell division of floral meristem cells including partially formed cell walls, increased DNA content, and multinucleated cells (Liu, Z., Running, M. P. and Meyerowitz, E. M. (1997). Development 124, 665–672). Here, we characterize a second defect of tso1 in influorescence meristem development and show that the enlarged influorescence in tso1 mutants results from repeated division of one inflorescence meristem into two or more influorescence meristems. Using a map-based approach, we isolated the TSO1 gene and found that TSO1 encodes a protein with cysteine-rich repeats bearing similarity to Drosophila Enhancer of zeste and its plant homologs. In situ TSO1 mRNA expression pattern and the nuclear localization of TSO1-GFP are consistent with a regulatory role of TSO1 in floral meristem cell division and in influorescence meristem organization.

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