The indeterminate floral apex1 gene regulates meristem determinacy and identity in the maize inflorescence

Development ◽  
2002 ◽  
Vol 129 (11) ◽  
pp. 2629-2638 ◽  
Author(s):  
Debbie Laudencia-Chingcuanco ◽  
Sarah Hake
Keyword(s):  
Double Mutant ◽  
Floral Meristem ◽  
Marker Genes ◽  
Integrated Process ◽  
Inflorescence Meristem ◽  
Mutant Analysis ◽  
Lateral Organs ◽  
Meristem Identity ◽  
Mutant Phenotypes ◽  
Floral Meristems

Meristems may be determinate or indeterminate. In maize, the indeterminate inflorescence meristem produces three types of determinate meristems: spikelet pair, spikelet and floral meristems. These meristems are defined by their position and their products. We have discovered a gene in maize, indeterminate floral apex1 (ifa1) that regulates meristem determinacy. The defect found in ifa1 mutants is specific to meristems and does not affect lateral organs. In ifa1 mutants, the determinate meristems become less determinate. The spikelet pair meristem initiates more than a pair of spikelets and the spikelet meristem initiates more than the normal two flowers. The floral meristem initiates all organs correctly, but the ovule primordium, the terminal product of the floral meristem, enlarges and proliferates, expressing both meristem and ovule marker genes. A role for ifa1 in meristem identity in addition to meristem determinacy was revealed by double mutant analysis. In zea agamous1 (zag1) ifa1 double mutants, the female floral meristem converts to a branch meristem whereas the male floral meristem converts to a spikelet meristem. In indeterminate spikelet1 (ids1) ifa1 double mutants, female spikelet meristems convert to branch meristems and male spikelet meristems convert to spikelet pair meristems. The double mutant phenotypes suggest that the specification of meristems in the maize inflorescence involves distinct steps in an integrated process.

scholarly journals Genetic control of branching pattern and floral identity during Petunia inflorescence development

Development ◽  
1998 ◽  
Vol 125 (4) ◽  
pp. 733-742 ◽  
Author(s):  
E. Souer ◽  
A. van der Krol ◽  
D. Kloos ◽  
C. Spelt ◽  
M. Bliek ◽  
...  
Keyword(s):  
In Situ Hybridisation ◽  
Floral Meristem ◽  
Branching Pattern ◽  
Inflorescence Meristem ◽  
Inflorescence Architecture ◽  
Phenotypic Analysis ◽  
Inflorescence Development ◽  
Meristem Identity ◽  
Floral Meristems

A main determinant of inflorescence architecture is the site where floral meristems are initiated. We show that in wild-type Petunia bifurcation of the inflorescence meristem yields two meristems of approximately equal size. One terminates into a floral meristem and the other maintains its inflorescence identity. By random transposon mutagenesis we have generated two mutants in which the architecture of the inflorescence is altered. In the extra petals- (exp) mutant the inflorescence terminates with the formation of a single terminal flower. Phenotypic analysis showed that exp is required for the bifurcation of inflorescence meristems. In contrast, the aberrant leaf and flower- (alf) mutant is affected in the specification of floral meristem identity while the branching pattern of the inflorescence remains unaltered. A weak alf allele was identified that, after bifurcation of the inflorescence meristem, yields a ‘floral’ meristem with partial inflorescence characteristics. By analysing independent transposon dTph1 insertion alleles we show that the alf locus encodes the Petunia FLORICAULA/LEAFY homolog. In situ hybridisation shows that alf is expressed in the floral meristem and also in the vegetative meristem. Differences and similarities between these Petunia mutants and mutations affecting inflorescence architecture in other species will be discussed.

scholarly journals CLAVATA1, a regulator of meristem and flower development in Arabidopsis

Development ◽  
1993 ◽  
Vol 119 (2) ◽  
pp. 397-418 ◽  
Author(s):  
S.E. Clark ◽  
M.P. Running ◽  
E.M. Meyerowitz
Keyword(s):  
Flower Development ◽  
Double Mutant ◽  
Apical Meristem ◽  
Expression Patterns ◽  
Floral Meristem ◽  
Homeotic Genes ◽  
Wild Type ◽  
Meristem Identity ◽  
Floral Meristems ◽  
Transition To Flowering

We have investigated the effects on plant development of mutations in the Arabidopsis thaliana CLAVATA1 gene. In clavata1 plants, vegetative, inflorescence and floral meristems are all enlarged relative to wild type. The apical meristem can fasciate in the more severe mutant alleles, and this fasciation can occur prior to the transition to flowering. Flowers of clavata1 plants can have increased numbers of organs in all four whorls, and can also have additional whorls not present in wild-type flowers. Double mutant combinations of clavata1 with agamous, apetala2, apetala3 and pistillata indicate that CLAVATA1 controls the underlying floral meristem structure upon which these homeotic genes act. Double mutant combinations of clavata1 with apetala1 and leafy indicate CLAVATA1 plays a role in establishing and maintaining floral meristem identity, in addition to its role in controlling meristem size. In support of this, RNA expression patterns of AGAMOUS and APETALA1 are altered in clavata1 flowers.

The ULTRAPETALA gene controls shoot and floral meristem size in Arabidopsis

Development ◽  
2001 ◽  
Vol 128 (8) ◽  
pp. 1323-1333 ◽  
Author(s):  
J.C. Fletcher
Keyword(s):  
Signal Transduction Pathway ◽  
Floral Meristem ◽  
Transduction Pathway ◽  
Wild Type ◽  
Inflorescence Meristem ◽  
Genetic Studies ◽  
Meristem Cell ◽  
Meristem Size ◽  
Cell Accumulation ◽  
Floral Meristems

The regulation of proper shoot and floral meristem size during plant development is mediated by a complex interaction of stem cell promoting and restricting factors. The phenotypic effects of mutations in the ULTRAPETALA gene, which is required to control shoot and floral meristem cell accumulation in Arabidopsis thaliana, are described. ultrapetala flowers contain more floral organs and whorls than wild-type plants, phenotypes that correlate with an increase in floral meristem size preceding organ initiation. ultrapetala plants also produce more floral meristems than wild-type plants, correlating with an increase in inflorescence meristem size without visible fasciation. Expression analysis indicates that ULTRAPETALA controls meristem cell accumulation partly by limiting the domain of CLAVATA1 expression. Genetic studies show that ULTRAPETALA acts independently of ERA1, but has overlapping functions with PERIANTHIA and the CLAVATA signal transduction pathway in controlling shoot and floral meristem size and meristem determinacy. Thus ULTRAPETALA defines a novel locus that restricts meristem cell accumulation in Arabidopsis shoot and floral meristems.

scholarly journals PROLIFERATING INFLORESCENCE MERISTEM, a MADS-Box Gene That Regulates Floral Meristem Identity in Pea

2002 ◽  
Vol 129 (3) ◽  
pp. 1150-1159 ◽  
Author(s):  
Scott A. Taylor ◽  
Julie M.I. Hofer ◽  
Ian C. Murfet ◽  
John D. Sollinger ◽  
Susan R. Singer ◽  
...  
Keyword(s):  
Floral Meristem ◽  
Mads Box ◽  
Inflorescence Meristem ◽  
Floral Meristem Identity ◽  
Meristem Identity ◽  
Mads Box Gene

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.

Separation of shoot and floral identity in Arabidopsis

Development ◽  
1999 ◽  
Vol 126 (6) ◽  
pp. 1109-1120 ◽  
Author(s):  
O.J. Ratcliffe ◽  
D.J. Bradley ◽  
E.S. Coen
Keyword(s):  
Shoot Apex ◽  
Floral Meristem ◽  
Floral Meristem Identity ◽  
Terminal Flower ◽  
Terminal Flower 1 ◽  
Type Pattern ◽  
Meristem Identity ◽  
Floral Meristems ◽  
Arabidopsis Plant ◽  
Meristem Identity Gene

The overall morphology of an Arabidopsis plant depends on the behaviour of its meristems. Meristems derived from the shoot apex can develop into either shoots or flowers. The distinction between these alternative fates requires separation between the function of floral meristem identity genes and the function of an antagonistic group of genes, which includes TERMINAL FLOWER 1. We show that the activities of these genes are restricted to separate domains of the shoot apex by different mechanisms. Meristem identity genes, such as LEAFY, APETALA 1 and CAULIFLOWER, prevent TERMINAL FLOWER 1 transcription in floral meristems on the apex periphery. TERMINAL FLOWER 1, in turn, can inhibit the activity of meristem identity genes at the centre of the shoot apex in two ways; first by delaying their upregulation, and second, by preventing the meristem from responding to LEAFY or APETALA 1. We suggest that the wild-type pattern of TERMINAL FLOWER 1 and floral meristem identity gene expression depends on the relative timing of their upregulation.

The Sox-domain containing geneDichaete/fish-hookacts in concert withvndandindto regulate cell fate in theDrosophilaneuroectoderm

Development ◽  
2002 ◽  
Vol 129 (5) ◽  
pp. 1165-1174 ◽  
Author(s):  
Guoyan Zhao ◽  
James B. Skeath
Keyword(s):  
Cell Fate ◽  
Nerve Cord ◽  
Double Mutant ◽  
Ventral Nerve Cord ◽  
Egf Receptor ◽  
Dorsoventral Axis ◽  
Mutant Analysis ◽  
Evolutionarily Conserved ◽  
Specific Manner ◽  
Important Regulator

In the Drosophila embryonic central nervous system, neural stem cells, called neuroblasts, acquire fates in a position-specific manner. Recent work has identified a set of genes that functions along the dorsoventral axis to enable neuroblasts that develop in different dorsoventral domains to acquire distinct fates. These genes include the evolutionarily conserved transcription factors ventral nerve cord defective and intermediate neuroblasts defective, as well as the Drosophila EGF receptor. We show that the Sox-domain-containing gene Dichaete/fish-hook also plays a crucial role to pattern the neuroectoderm along the DV axis. Dichaete is expressed in the medial and intermediate columns of the neuroectoderm, and mutant analysis indicates that Dichaete regulates cell fate and neuroblast formation in these domains. Molecular epistasis tests, double mutant analysis and dosage-sensitive interactions demonstrate that during these processes, Dichaete functions in parallel with ventral nerve cord defective and intermediate neuroblasts defective, and downstream of EGF receptor signaling to mediate its effect on development. These results identify Dichaete as an important regulator of dorsoventral pattern in the neuroectoderm, and indicate that Dichaete acts in concert with ventral nerve cord defective and intermediate neuroblasts defective to regulate pattern and cell fate in the neuroectoderm.

Sign in / Sign up

Export Citation Format

Share Document