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.

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.

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 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 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 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.

PpAG1, a homolog of AGAMOUS, expressed in developing peach flowers and fruit

2006 ◽  
Vol 84 (5) ◽  
pp. 767-776 ◽  
Author(s):  
Teresa Martin ◽  
Ming Hu ◽  
Hélène Labbé ◽  
Sylvia McHugh ◽  
Antonet Svircev ◽  
...  
Keyword(s):  
Prunus Persica ◽  
Single Gene ◽  
Floral Organ ◽  
Floral Meristem ◽  
35S Promoter ◽  
Mads Box ◽  
Specific Expression ◽  
Organ Identity ◽  
Constitutive Overexpression ◽  
Mads Box Gene

MADS-box transcription factors are known to play a central role in floral organ identity and floral meristem determinacy in many gymnosperms and angiosperms. Studies of this nature are limited in fruit tree species despite the economic importance of this group. A peach ( Prunus persica (L.) Batsch) gene, PpAG1, was isolated and shown to be homologous to the Arabidopsis thaliana (L.) Heynh. MADS-box gene AGAMOUS (AG). It is a single gene in peach and codes for a type II or MIKC-type MADS-box protein. The features of the deduced protein sequence indicate that it is similar to other AG homologs from woody plant species. The spatial and developmental patterns of expression parallel those of AG and homologs from other angiosperms with similar floral structures but with some minor differences. In the floral meristem, where AG is responsible for conversion of the vegetative meristem into the floral meristem, the differentiation of the whorls that generate the carpels and stamens coincides with the tissue-specific expression of PpAG1. It continues to be expressed in the ovules, developing fruit and seeds that subsequently develop from the carpels. Constitutive overexpression of PpAG1 in Arabidopsis, using the 35S promoter, caused the homeotic conversion of sepals to carpelloid tissues and altered petal development. This is consistent with C-function genes according to the ABC model of flower development. The data support the conclusion that PpAG1 is the peach homolog of Arabidopsis AG.

scholarly journals MicroRNA-mediated regulation of flower development in grasses

2017 ◽  
Vol 63 (4) ◽  
Author(s):  
Aleksandra Smoczynska ◽  
Zofia Szweykowska-Kulinska
Keyword(s):  
Flower Development ◽  
Floral Development ◽  
Genetic Model ◽  
Genetic Regulation ◽  
Floral Organ ◽  
Reproductive Organs ◽  
Flower Structure ◽  
Flower Opening ◽  
Organ Identity ◽  
Floral Organ Identity Genes

Flower structure in grasses is very unique. There are no petals or sepals like in eudicots but instead flowers develop bract-like structures –palea and lemma. Reproductive organs are enclosed by round lodicule that not only protects reproductive organs but also play important role during flower opening. First genetic model for floral organ development was proposed 25 years ago and it was based on the research on model eudicots. Since then studies have been made to answer the question whether this model could be applicable in case of monocots. Genes from all found in eudicots classes have been also indentified in genomes of such monocots like rice, maize or barley. What’s more it seems that miRNA-mediated regulation of floral organ genes that was observed in case of Arabidopsis thaliana also has a place in monocots. MiRNA172, miRNA159, miRNA171 and miRNA396 regulate expression of floral organ identity genes in barley, rice and maize affecting various features of flower structure from formation of lemma and palea to development of reproductive organs. Model of floral development in grasses and its genetic regulation in not yet fully characterized. Further studies on both model eudicots and grasses are needed to unravel this topic. This review provides general overview of genetic model of flower organ identity specification in monocots and it’s miRNA-mediated regulation.

scholarly journals The movement of a leaf-derived mobile AGL24 mRNA specifies floral organ identity in Arabidopsis

2020 ◽  
Author(s):  
Nien-Chen Huang ◽  
Huan-Chi Tien ◽  
Tien-Shin Yu
Keyword(s):  
Plant Development ◽  
Developmental Plasticity ◽  
Protein Translation ◽  
Floral Organ ◽  
Floral Meristem ◽  
Long Distance ◽  
Floral Organ Identity ◽  
Organ Identity ◽  
Meristem Identity

AbstractCell-to-cell and inter-organ communication play pivotal roles in synchronizing and coordinating plant development. In addition to serving as templates for protein translation within cells, many mRNAs can move and exert their function non-cell-autonomously. However, because the proteins encoded by some mobile mRNAs are also mobile, whether the systemic function of mobile mRNAs is attributed to proteins transported distally or translated locally remains controversial. Here, we show that Arabidopsis AGAMOUS-LIKE 24 (AGL24) mRNA acts as a leaf-derived signal to specify meristem identity. AGL24 is expressed in both apex and leaves. Upon floral meristem (FM) transition, apex-expressed AGL24 is transcriptionally inhibited by APETALA1 (AP1) to ensure FM differentiation. The leaf-expressed AGL24 can act as a mobile signal to bypass AP1 inhibition and revert FM differentiation. Although AGL24 mRNA is expressed in leaves, AGL24 protein is rapidly degraded in leaves. In contrast, AGL24 mRNA can move long distance from leaf to apex where the translocated AGL24 mRNAs can be used as templates to translate into proteins. Thus, the movement of AGL24 mRNA can provide the developmental plasticity to fit with environmental dynamics.

scholarly journals Global Quantitative Proteomics Studies Revealed Tissue-Preferential Expression and Phosphorylation of Regulatory Proteins in Arabidopsis

2020 ◽  
Vol 21 (17) ◽  
pp. 6116
Author(s):  
Jianan Lu ◽  
Ying Fu ◽  
Mengyu Li ◽  
Shuangshuang Wang ◽  
Jingya Wang ◽  
...  
Keyword(s):  
Quantitative Proteomics ◽  
Expression Patterns ◽  
Floral Organ ◽  
Reproductive Organs ◽  
Regulatory Proteins ◽  
Vegetative Organs ◽  
Preferential Expression ◽  
Functional Studies ◽  
Phosphorylated Proteins ◽  
Stage 1

Organogenesis in plants occurs across all stages of the life cycle. Although previous studies have identified many genes as important for either vegetative or reproductive development at the RNA level, global information on translational and post-translational levels remains limited. In this study, six Arabidopsis stages/organs were analyzed using quantitative proteomics and phosphoproteomics, identifying 2187 non-redundant proteins and evidence for 1194 phosphoproteins. Compared to the expression observed in cauline leaves, the expression of 1445, 1644, and 1377 proteins showed greater than 1.5-fold alterations in stage 1–9 flowers, stage 10–12 flowers, and open flowers, respectively. Among these, 294 phosphoproteins with 472 phosphorylation sites were newly uncovered, including 275 phosphoproteins showing differential expression patterns, providing molecular markers and possible candidates for functional studies. Proteins encoded by genes preferentially expressed in anther (15), meiocyte (4), or pollen (15) were enriched in reproductive organs, and mutants of two anther-preferentially expressed proteins, acos5 and mee48, showed obviously reduced male fertility with abnormally organized pollen exine. In addition, more phosphorylated proteins were identified in reproductive stages (1149) than in the vegetative organs (995). The floral organ-preferential phosphorylation of GRP17, CDC2/CDKA.1, and ATSK11 was confirmed with western blot analysis. Moreover, phosphorylation levels of CDPK6 and MAPK6 and their interacting proteins were elevated in reproductive tissues. Overall, our study yielded extensive data on protein expression and phosphorylation at six stages/organs and provides an important resource for future studies investigating the regulatory mechanisms governing plant development.

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