Shoot apical meristem and cotyledon formation during Arabidopsis embryogenesis: interaction among the CUP-SHAPED COTYLEDON and SHOOT MERISTEMLESS genes

Development ◽  
1999 ◽  
Vol 126 (8) ◽  
pp. 1563-1570 ◽  
Author(s):  
M. Aida ◽  
T. Ishida ◽  
M. Tasaka
Keyword(s):  
Pattern Formation ◽  
Mrna Expression ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Higher Plants ◽  
Expression Patterns ◽  
Genetic Interactions ◽  
Apical Region ◽  
Arabidopsis Embryogenesis ◽  
Shoot Meristemless

The shoot apical meristem and cotyledons of higher plants are established during embryogenesis in the apex. Redundant CUP-SHAPED COTYLEDON 1 (CUC1) and CUC2 as well as SHOOT MERISTEMLESS (STM) of Arabidopsis are required for shoot apical meristem formation and cotyledon separation. To elucidate how the apical region of the embryo is established, we investigated genetic interactions among CUC1, CUC2 and STM, as well as the expression patterns of CUC2 and STM mRNA. Expression of these genes marked the incipient shoot apical meristem as well as the boundaries of cotyledon primordia, consistent with their roles for shoot apical meristem formation and cotyledon separation. Genetic and expression analyses indicate that CUC1 and CUC2 are redundantly required for expression of STM to form the shoot apical meristem, and that STM is required for proper spatial expression of CUC2 to separate cotyledons. A model for pattern formation in the apical region of the Arabidopsis embryo is presented.

Embryonic shoot apical meristem formation in higher plants

2002 ◽  
Vol 115 (6) ◽  
pp. 411-417 ◽  
Author(s):  
Shinobu Takada ◽  
Masao Tasaka
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Higher Plants

Combined SHOOT MERISTEMLESS and WUSCHEL trigger ectopic organogenesis inArabidopsis

Development ◽  
2002 ◽  
Vol 129 (13) ◽  
pp. 3207-3217 ◽  
Author(s):  
Jean-Luc Gallois ◽  
Claire Woodward ◽  
G. Venugopala Reddy ◽  
Robert Sablowski
Keyword(s):  
Stem Cells ◽  
Cell Division ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Aerial Parts ◽  
Undifferentiated Cells ◽  
Activate Cell ◽  
Almost All ◽  
Differentiation Pathways ◽  
Shoot Meristemless

Almost all aerial parts of plants are continuously generated at the shoot apical meristem (SAM). To maintain a steady pool of undifferentiated cells in the SAM while continuously generating new organs, it is necessary to balance the rate of cell division with the rate of entrance into differentiation pathways. In the Arabidopsis meristem, SHOOT MERISTEMLESS (STM) and WUSCHEL (WUS) are necessary to keep cells undifferentiated and dividing. Here, we tested whether ectopic STM and WUS functions are sufficient to revert differentiation and activate cell division in differentiating tissues. Ectopic STM and WUS functions interacted non-additively and activated a subset of meristem functions, including cell division, CLAVATA1 expression and organogenesis, but not correct phyllotaxy or meristem self-maintenance. Our results suggest that WUS produces a non-cell autonomous signal that activates cell division in combination with STM and that combined WUS/STM functions can initiate the progression from stem cells to organ initiation.

scholarly journals Variability in porcine microRNA genes and its association with mRNA expression phenotypes

2020 ◽  
Author(s):  
Emilio Mármol-Sánchez ◽  
Dailu Guan ◽  
Raquel Quintanilla ◽  
Raul Tonda ◽  
Marcel Amills
Keyword(s):  
Gene Expression ◽  
Mrna Expression ◽  
Binding Sites ◽  
Expression Patterns ◽  
Critical Role ◽  
Apical Region ◽  
Seed Region ◽  
Association Analyses ◽  
Mirna Genes ◽  
Wide Range

AbstractBackgroundMature microRNAs (miRNAs) play an important role in repressing the expression of a wide range of protein coding transcripts by promoting their degradation or inhibiting their translation into functional proteins. The presence of segregating polymorphisms inside miRNA loci and their corresponding 3’UTR binding sites might disrupt canonical conserved miRNA-mRNA pairing, thus modifying gene expression patterns.ResultsWe aimed to investigate the variability of miRNA genes and their putative binding sites by analyzing whole-genome sequences from 120 pigs and wild boars from Europe and Asia. In total, 285 SNPs residing within miRNA loci were detected. From these, 221 were located in precursor regions, whereas 52 and 12 mapped to mature and seed regions, respectively. Moreover, a total of 109,724 polymorphisms were identified in predicted 7mer-m8 miRNA binding sites within porcine 3’UTRs. A principal components analysis revealed a clear genetic divergence between Asian and European samples, which was particularly strong for 3’UTR sequences. We also observed that miRNA genes show reduced polymorphism compared with other non-miRNA regions. To assess the potential consequences of miRNA polymorphisms, we sequenced the genomes of 5 Duroc pigs and, by doing so, we identified 15 miRNA SNPs that were genotyped in the offspring (N = 345) of the five boars. Association analyses between miRNA SNPs and hepatic and muscle microarray data allowed us to identify 4 polymorphisms displaying significant associations. Particularly interesting was the rs319154814 polymorphism (G/A), located in the apical loop of the ssc-miR-326 precursor sequence. This polymorphism is predicted to cause a subtle hairpin rearrangement that improves the accessibility to processing enzymatic factors.ConclusionsPorcine miRNA genes show a reduced variability, particularly in the seed region which plays a critical role in miRNA binding. Although it is generally assumed that SNPs mapping to the seed region are the ones with the strongest consequences on mRNA expression, we show that a SNP mapping to the apical region of ssc-miR-326 is associated with the mRNA expression of several of its predicted targets. This result suggests that porcine miRNA variability mapping within and outside the seed region could have important regulatory effects on gene expression.

The CUP-SHAPED COTYLEDON1 gene of Arabidopsis regulates shoot apical meristem formation

Development ◽  
2001 ◽  
Vol 128 (7) ◽  
pp. 1127-1135 ◽  
Author(s):  
S. Takada ◽  
K. Hibara ◽  
T. Ishida ◽  
M. Tasaka
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Molecular Mechanisms ◽  
Higher Plants ◽  
Adventitious Shoots ◽  
Floral Organ ◽  
Loss Of Function ◽  
Nac Domain ◽  
Redundant Genes ◽  
Domain Protein

In higher plants, molecular mechanisms regulating shoot apical meristem (SAM) formation and organ separation are largely unknown. The CUC1 (CUP-SHAPED COTYLEDON1) and CUC2 are functionally redundant genes that are involved in these processes. We cloned the CUC1 gene by a map-based approach, and found that it encodes a NAC-domain protein highly homologous to CUC2. CUC1 mRNA was detected in the presumptive SAM during embryogenesis, and at the boundaries between floral organ primordia. Surprisingly, overexpression of CUC1 was sufficient to induce adventitious shoots on the adaxial surface of cotyledons. Expression analyses in the overexpressor and in loss-of-function mutants suggest that CUC1 acts upstream of the SHOOT MERISTEMLESS gene.

scholarly journals Diversity of phyllotaxis in land plants in reference to the shoot apical meristem structure

2016 ◽  
Vol 85 (4) ◽  
Author(s):  
Edyta M. Gola ◽  
Alicja Banasiak
Keyword(s):  
Pattern Formation ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Land Plants ◽  
Phyllotactic Pattern ◽  
Lateral Organs ◽  
Spatio Temporal

Regularity and periodicity in the arrangements of organs in all groups of land plants raise questions about the mechanisms underlying phyllotactic pattern formation. The initiation of the lateral organs (leaves, flowers, etc.), and thus, their spatio-temporal positioning, occurs in the shoot apical meristem (SAM) and is related to the structure and organogenic activity of the meristem. In this review, we present some aspects of the diversity and stability of phyllotactic patterns in the major lineages of land plants, from bryophytes to angiosperms, in which SAM structures differ significantly. In addition, we discuss some of the possible mechanisms involved in the formation of the recurring arrangement of the lateral organs.

The shoot apical meristem and development of vascular architectureThis review is one of a selection of papers published on the Special Theme of Shoot Apical Meristems.

2006 ◽  
Vol 84 (11) ◽  
pp. 1660-1671 ◽  
Author(s):  
Nancy G. Dengler
Keyword(s):  
Arabidopsis Thaliana ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Leucine Zipper ◽  
Vascular Tissue ◽  
Vascular System ◽  
Expression Patterns ◽  
Three Dimensional ◽  
Integrative Model ◽  
Class Iii

The shoot apical meristem (SAM) functions to generate external architecture and internal tissue pattern as well as to maintain a self-perpetuating population of stem-cell-like cells. The internal three-dimensional architecture of the vascular system corresponds closely to the external arrangement of lateral organs, or phyllotaxis. This paper reviews this correspondence for dicotyledonous plants in general and in Arabidopsis thaliana (L.) Heynh., specifically. Analysis is partly based on the expression patterns of the class III homeodomain-leucine zipper transcription factor ARABIDOPSIS THALIANA HOMEOBOX GENE 8 (ATHB8), a marker of the procambial and preprocambial stages of vascular development, and on the anatomical criteria for recognizing vascular tissue pattern. The close correspondence between phyllotaxis and vascular pattern present in mature tissues arises at early stages of development, at least by the first plastochron of leaf primordium outgrowth. Current literature provides an integrative model in which local variation in auxin concentration regulates both primordium formation on the SAM and the first indications of a procambial prepattern in the position of primordium leaf trace as well as in the elaboration of leaf vein pattern. The prospects for extending this model to the development of the complex three-dimensional vascular architecture of the shoot are promising.

scholarly journals Expression of maize KNOTTED1 related homeobox genes in the shoot apical meristem predicts patterns of morphogenesis in the vegetative shoot

Development ◽  
1994 ◽  
Vol 120 (2) ◽  
pp. 405-413 ◽  
Author(s):  
D. Jackson ◽  
B. Veit ◽  
S. Hake
Keyword(s):  
Shoot Apical Meristem ◽  
Leaf Development ◽  
Apical Meristem ◽  
Expression Patterns ◽  
Homeobox Genes ◽  
Homeobox Gene ◽  
Vegetative Shoot ◽  
Lateral Organs ◽  
Floral Meristems ◽  
Shoot Meristems

In this paper we describe the expression patterns of a family of homeobox genes in maize and their relationship to organogenic domains in the vegetative shoot apical meristem. These genes are related by sequence to KNOTTED1, a gene characterized by dominant neomorphic mutations which perturb specific aspects of maize leaf development. Four members of this gene family are expressed in shoot meristems and the developing stem, but not in determinate lateral organs such as leaves or floral organs. The genes show distinct expression patterns in the vegetative shoot apical meristem that together predict the site of leaf initiation and the basal limit of the vegetative ‘phytomer’ or segmentation unit of the shoot. These genes are also expressed in the inflorescence and floral meristems, where their patterns of expression are more similar, and they are not expressed in root apical meristems. These findings are discussed in relation to other studies of shoot apical meristem organization as well as possible commonality of homeobox gene function in the animal and plant kingdoms.

Formation of the shoot apical meristem in Arabidopsis thaliana: an analysis of development in the wild type and in the shoot meristemless mutant

Development ◽  
1993 ◽  
Vol 119 (3) ◽  
pp. 823-831 ◽  
Author(s):  
M. K. Barton ◽  
R. S. Poethig
Keyword(s):  
Tissue Culture ◽  
Arabidopsis Thaliana ◽  
Embryo Development ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Adventitious Shoot ◽  
Shoot Meristem ◽  
Wild Type ◽  
In The Wild ◽  
Shoot Meristemless

The primary shoot apical meristem of Arabidopsis is initiated late in embryogenesis, after the initiation of the cotyledons. We have identified a gene, called SHOOT MERISTEMLESS, which is critical for this process. shoot meristemless mutant seedlings lack a shoot apical meristem but are otherwise healthy and viable. The anatomy of mutant embryos demonstrates that the shoot meristemless-1 mutation completely blocks the initiation of the shoot apical meristem, but has no other obvious effects on embryo development. The failure of shoot meristemless tissue to regenerate shoots in tissue culture suggests that this gene regulates adventitious shoot meristem formation, as well as embryonic shoot meristem formation.

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