SEMAPHORE1 functions during the regulation of ancestrally duplicated knox genes and polar auxin transport in maize

Development ◽  
2002 ◽  
Vol 129 (11) ◽  
pp. 2663-2673 ◽  
Author(s):  
Michael J. Scanlon ◽  
David C. Henderson ◽  
Brad Bernstein
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Auxin Transport ◽  
Lateral Roots ◽  
Ectopic Expression ◽  
Polar Auxin Transport ◽  
Knox Gene ◽  
Endosperm Tissue ◽  
Knox Genes ◽  
Class 1

The expression of class 1 knotted1-like homeobox (knox) genes affects numerous plant developmental processes, including cell-fate acquisition, lateral organ initiation, and maintenance of shoot apical meristems. The SEMAPHORE1 gene product is required for the negative regulation of a subset of maize knox genes, the duplicated loci rough sheath 1 and gnarley1 (knox4). Recessive mutations in semaphore1 result in the ectopic expression of knox genes in leaf and endosperm tissue. Genetic analyses suggest that SEMAPHORE1 may regulate knox gene expression in a different developmental pathway than ROUGH SHEATH2, the first-identified regulator of knox gene expression in maize. Mutations at semaphore1 are pleiotropic, disrupting specific domains of the shoot. However, unlike previously described mutations that cause ectopic knox gene expression, semaphore1 mutations affect development of the embryo, endosperm, lateral roots, and pollen. Moreover, polar transport of the phytohormone auxin is significantly reduced in semaphore1 mutant shoots. The data suggest that many of the pleiotropic semaphore1 phenotypes result from defective polar auxin transport (PAT) in sem1 mutant shoots, and support models correlating down-regulated knox gene expression and PAT in maize shoots.

The rough sheath2 gene negatively regulates homeobox gene expression during maize leaf development

Development ◽  
1998 ◽  
Vol 125 (15) ◽  
pp. 2857-2865 ◽  
Author(s):  
R. Schneeberger ◽  
M. Tsiantis ◽  
M. Freeling ◽  
J.A. Langdale
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Higher Plants ◽  
Leaf Shape ◽  
Ectopic Expression ◽  
Homeobox Gene ◽  
Current Evidence ◽  
Leaf Cell ◽  
Knox Gene ◽  
Knox Genes

Leaves of higher plants are produced in a sequential manner through the differentiation of cells that are derived from the shoot apical meristem. Current evidence suggests that this transition from meristematic to leaf cell fate requires the down-regulation of knotted1-like homeobox (knox) gene expression. If knox gene expression is not repressed, overall leaf shape and cellular differentiation within the leaf are perturbed. In order to identify genes that are required for the aquisition of leaf cell fates, we have genetically screened for recessive mutations that confer phenotypes similar to dominant mutations (e.g. Knotted1 and Rough sheath1) that result in the ectopic expression of class I knox genes. Independently derived mutations at the rough sheath2 (rs2) locus condition a range of pleiotropic leaf, node and internode phenotypes that are sensitive to genetic background and environment. Phenotypes include dwarfism, leaf twisting, disorganized differentiation of the blade-sheath boundary, aberrant vascular patterning and the generation of semi-bladeless leaves. knox genes are initially repressed in rs2 mutants as leaf founder cells are recruited in the meristem. However, this repression is often incomplete and is not maintained as the leaf progresses through developement. Expression studies indicate that three knox genes are ectopically or over-expressed in developing primordia and in mature leaves. We therefore propose that the rs2 gene product acts to repress knox gene expression (either directly or indirectly) and that rs2 gene action is essential for the elaboration of normal leaf morphology.

scholarly journals Auxin methylation is required for differential growth inArabidopsis

2018 ◽  
Vol 115 (26) ◽  
pp. 6864-6869 ◽  
Author(s):  
Mohamad Abbas ◽  
Jorge Hernández-García ◽  
Stephan Pollmann ◽  
Sophia L. Samodelov ◽  
Martina Kolb ◽  
...  
Keyword(s):  
Gene Expression ◽  
Auxin Transport ◽  
Polar Auxin Transport ◽  
Asymmetric Distribution ◽  
Loss Of Function ◽  
Differential Growth ◽  
Specific Expression ◽  
Auxin Homeostasis ◽  
Auxin Distribution ◽  
Gene Expression Levels

Asymmetric auxin distribution is instrumental for the differential growth that causes organ bending on tropic stimuli and curvatures during plant development. Local differences in auxin concentrations are achieved mainly by polarized cellular distribution of PIN auxin transporters, but whether other mechanisms involving auxin homeostasis are also relevant for the formation of auxin gradients is not clear. Here we show that auxin methylation is required for asymmetric auxin distribution across the hypocotyl, particularly during its response to gravity. We found that loss-of-function mutants inArabidopsis IAA CARBOXYL METHYLTRANSFERASE1(IAMT1) prematurely unfold the apical hook, and that their hypocotyls are impaired in gravitropic reorientation. This defect is linked to an auxin-dependent increase inPINgene expression, leading to an increased polar auxin transport and lack of asymmetric distribution of PIN3 in theiamt1mutant. Gravitropic reorientation in theiamt1mutant could be restored with either endodermis-specific expression ofIAMT1or partial inhibition of polar auxin transport, which also results in normalPINgene expression levels. We propose that IAA methylation is necessary in gravity-sensing cells to restrict polar auxin transport within the range of auxin levels that allow for differential responses.

Class 1 KNOX Gene Expression Supports the Selaginella Rhizophore Concept

2010 ◽  
Vol 53 (4) ◽  
pp. 268-274 ◽  
Author(s):  
Junko Kawai ◽  
Yoichi Tanabe ◽  
Sumitomo Soma ◽  
Motomi Ito
Keyword(s):  
Gene Expression ◽  
Knox Gene ◽  
Class 1

Transgenic lines of Begonia maculata generated by ectopic expression of PttKN1

Biologia ◽  
2011 ◽  
Vol 66 (2) ◽  
Author(s):  
Quan-le Xu ◽  
Jiang-ling Dong ◽  
Nan Gao ◽  
Mei-yu Ruan ◽  
Hai-yan Jia ◽  
...  
Keyword(s):  
Transgenic Plants ◽  
Ectopic Expression ◽  
Class I ◽  
Wild Type Plant ◽  
Wild Type ◽  
Knox Gene ◽  
Knox Genes ◽  
Pttkn1 Gene ◽  
Transgenic Lines ◽  
First Time

AbstractKNOX (KNOTTED1-like homeobox) genes encode homeodomain-containing transcription factors which play crucial roles in meristem maintenance and proper patterning of organ initiation. PttKN1 gene, isolated from the vascular cambium of hybrid aspen (Populus tremula × P. tremuloides), is a member of class I KNOX gene family. In order to understand the roles of PttKN1 gene in meristem activity and morphogenesis as well as to explore the possibility to generate novel ornamental lines via its ectopic expression, it was introduced into the genome of Begonia maculata Raddi by Agrobacterium tumefasciens-mediated gene transformation here. Four types of transgenic plants were observed, namely coral-like (CL) type, ectopic foliole (EF) type, phyllotaxy-irregular (IP) type and cup-shaped (CS) type, which were remarkably different from corresponding wild type and were not also observed in the regenerated plantlets of wild type plant. Among these four types of transgenic plants, the phenotype of coral-like was observed for the first time in the transformants ectopically expressed KNOX genes. The observation of scanning electron microscope (SEM) showed ectopic meristems on the adaxial leaf surface of the transformants. Interestingly, the plantlets with ectopic foliole could generate new ectopic folioles from the original ectopic folioles again, and the plants regenerated from the EF-type transformants could also maintain the original morphology. The same specific RT-PCR band of the four types of transgenic plantlets showed that PttKN1 was ectopically expressed. All these data demonstrated that the ectopic expression of PttKN1 caused a series of alterations in morphology which provided possibilities producing novel ornamental lines and that PttKN1 played important roles in meristem initiation, maintenance and organogenesis events as other class I KNOX genes.

Mechanisms that control knox gene expression in the Arabidopsis shoot

Development ◽  
2000 ◽  
Vol 127 (24) ◽  
pp. 5523-5532 ◽  
Author(s):  
N. Ori ◽  
Y. Eshed ◽  
G. Chuck ◽  
J.L. Bowman ◽  
S. Hake
Keyword(s):  
Gene Expression ◽  
Knox Gene ◽  
Phenotypic Characteristics ◽  
Knox Genes ◽  
Meristem Maintenance ◽  
Leaf Differentiation ◽  
Shoot Meristems

Knotted1-like homeobox (knox) genes are expressed in specific patterns within shoot meristems and play an important role in meristem maintenance. Misexpression of the knox genes, KNAT1 or KNAT2, in Arabidopsis produces a variety of phenotypes, including lobed leaves and ectopic stipules and meristems in the sinus, the region between lobes. We sought to determine the mechanisms that control knox gene expression in the shoot by examining recessive mutants that share phenotypic characteristics with 35S::KNAT1 plants. Double mutants of serrate (se) with either asymmetric1 (as1) or asymmetric2 (as2) showed lobed leaves, ectopic stipules in the sinuses and defects in the timely elongation of sepals, petals and stamens, similar to 35S::KNAT1 plants. Ectopic stipules and in rare cases, ectopic meristems, were detected in the sinuses on plants that were mutant for pickle and either as1 or as2. KNAT1 and KNAT2 were misexpressed in the leaves and flowers of single as1 and as2 mutants and in the sinuses of leaves of the different double mutants, but not in se or pickle single mutants. These results suggest that AS1 and AS2 promote leaf differentiation through repression of knox expression in leaves, and that SE and PKL globally restrict the competence to respond to genes that promote morphogenesis.

The zinc finger proteins Pannier and GATA4 function as cardiogenic factors in Drosophila

Development ◽  
1999 ◽  
Vol 126 (24) ◽  
pp. 5679-5688 ◽  
Author(s):  
K. Gajewski ◽  
N. Fossett ◽  
J.D. Molkentin ◽  
R.A. Schulz
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Zinc Finger ◽  
Heart Development ◽  
Ectopic Expression ◽  
Cell Formation ◽  
Homeodomain Protein ◽  
Gata Factor ◽  
Cardiac Gene Expression ◽  
Cardiac Gene

The regulation of cardiac gene expression by GATA zinc finger transcription factors is well documented in vertebrates. However, genetic studies in mice have failed to demonstrate a function for these proteins in cardiomyocyte specification. In Drosophila, the existence of a cardiogenic GATA factor has been implicated through the analysis of a cardial cell enhancer of the muscle differentiation gene D-mef2. We show that the GATA gene pannier is expressed in the dorsal mesoderm and required for cardial cell formation while repressing a pericardial cell fate. Ectopic expression of Pannier results in cardial cell overproduction, while co-expression of Pannier and the homeodomain protein Tinman synergistically activate cardiac gene expression and induce cardial cells. The related GATA4 protein of mice likewise functions as a cardiogenic factor in Drosophila, demonstrating an evolutionarily conserved function between Pannier and GATA4 in heart development.

scholarly journals GATA4 blocks squamous epithelial cell gene expression in human esophageal squamous cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Roman Stavniichuk ◽  
Ann DeLaForest ◽  
Cayla A. Thompson ◽  
James Miller ◽  
Rhonda F. Souza ◽  
...  
Keyword(s):  
Gene Expression ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Fate ◽  
Gene Amplification ◽  
Marker Gene ◽  
Ectopic Expression ◽  
Marker Genes ◽  
Cell Marker ◽  
Squamous Epithelial Cell

AbstractGATA4 promotes columnar epithelial cell fate during gastric development. When ectopically expressed in the developing mouse forestomach, the tissue emerges as columnar-like rather than stratified squamous with gene expression changes that parallel those observed in the pre-malignant squamous to columnar metaplasia known as Barrett’s esophagus (BE). GATA4 mRNA up-regulation and gene amplification occur in BE and its associated cancer, esophageal adenocarcinoma (EAC), and GATA4 gene amplification correlates with poor patient outcomes. Here, we explored the effect of ectopic expression of GATA4 in mature human esophageal squamous epithelial cells. We found that GATA4 expression in esophageal squamous epithelial cells compromised squamous cell marker gene expression and up-regulated expression of the canonical columnar cell cytokeratin KRT8. We observed GATA4 occupancy in the p63, KRT5, and KRT15 promoters, suggesting that GATA4 directly represses expression of squamous epithelial cell marker genes. Finally, we verified GATA4 protein expression in BE and EAC and found that exposure of esophageal squamous epithelial cells to acid and bile, known BE risk factors, induced GATA4 mRNA expression. We conclude that GATA4 suppresses expression of genes marking the stratified squamous epithelial cell lineage and that this repressive action by GATA4 may have implications in BE and EAC.

scholarly journals The PINOID protein kinase regulates organ development in Arabidopsis by enhancing polar auxin transport

Development ◽  
2001 ◽  
Vol 128 (20) ◽  
pp. 4057-4067 ◽  
Author(s):  
René Benjamins ◽  
Ab Quint ◽  
Dolf Weijers ◽  
Paul Hooykaas ◽  
Remko Offringa
Keyword(s):  
Protein Kinase ◽  
Auxin Transport ◽  
Vascular Tissue ◽  
Primary Root ◽  
Ectopic Expression ◽  
Polar Auxin Transport ◽  
Fine Tuning ◽  
35S Promoter ◽  
Serine Threonine Kinase ◽  
Transport Inhibitors

Arabidopsis pinoid mutants show a strong phenotypic resemblance to the pin-formed mutant that is disrupted in polar auxin transport. The PINOID gene was recently cloned and found to encode a protein-serine/threonine kinase. Here we show that the PINOID gene is inducible by auxin and that the protein kinase is present in the primordia of cotyledons, leaves and floral organs and in vascular tissue in developing organs or proximal to meristems. Overexpression of PINOID under the control of the constitutive CaMV 35S promoter (35S::PID) resulted in phenotypes also observed in mutants with altered sensitivity to or transport of auxin. A remarkable characteristic of high expressing 35S::PID seedlings was a frequent collapse of the primary root meristem. This event triggered lateral root formation, a process that was initially inhibited in these seedlings. Both meristem organisation and growth of the primary root were rescued when seedlings were grown in the presence of polar auxin transport inhibitors, such as naphthylphtalamic acid (NPA). Moreover, ectopic expression of PINOID cDNA under control of the epidermis-specific LTP1 promoter provided further evidence for the NPA-sensitive action of PINOID. The results presented here indicate that PINOID functions as a positive regulator of polar auxin transport. We propose that PINOID is involved in the fine-tuning of polar auxin transport during organ formation in response to local auxin concentrations.

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