scholarly journals Molecular and cellular aspects of the shoot apical meristems organization of vascular plants

2015 ◽  
Author(s):  
Ekaterina Klimova ◽  
Olga Voitsekhovskaja
Keyword(s):  
Transcription Factors ◽  
Shoot Apical Meristem ◽  
Vascular Plants ◽  
Apical Meristem ◽  
Flowering Plants ◽  
Knox Genes ◽  
Apical Meristems ◽  
Autonomous Regulation ◽  
Shoot Apical Meristems

Transfer of developmental regulators, such as miRNA and transcription factors, through plasmodesmata represents one of the key mechanisms regulating morphogenesis in angiosperms. This mechanism has been termed non-cell-autonomous regulation. At present it is not known whether this process is involved in the morphogenesis of plants belonging to the evolutionarily ancient taxa. Importantly, structure and symplastic organization of apical meristems in the representatives of such taxa significantly differ from those in flowering plants. The non-cell-autonomous transcription factors encoded by the KNOX genes which regulate functions of the shoot apical meristem may become a promising model to study this issue. Refs 102. Figs 3.

scholarly journals Class I KNOX Is Related to Determinacy during the Leaf Development of the Fern Mickelia scandens (Dryopteridaceae)

2020 ◽  
Vol 21 (12) ◽  
pp. 4295 ◽  
Author(s):  
Rafael Cruz ◽  
Gladys F. A. Melo-de-Pinna ◽  
Alejandra Vasco ◽  
Jefferson Prado ◽  
Barbara A. Ambrose
Keyword(s):  
Leaf Development ◽  
Apical Meristem ◽  
Class I ◽  
Seed Plants ◽  
Histone H4 ◽  
Knox Genes ◽  
Apical Meristems ◽  
Cell Divisions ◽  
Shoot Apical Meristems

Unlike seed plants, ferns leaves are considered to be structures with delayed determinacy, with a leaf apical meristem similar to the shoot apical meristems. To better understand the meristematic organization during leaf development and determinacy control, we analyzed the cell divisions and expression of Class I KNOX genes in Mickelia scandens, a fern that produces larger leaves with more pinnae in its climbing form than in its terrestrial form. We performed anatomical, in situ hybridization, and qRT-PCR experiments with histone H4 (cell division marker) and Class I KNOX genes. We found that Class I KNOX genes are expressed in shoot apical meristems, leaf apical meristems, and pinnae primordia. During early development, cell divisions occur in the most distal regions of the analyzed structures, including pinnae, and are not restricted to apical cells. Fern leaves and pinnae bear apical meristems that may partially act as indeterminate shoots, supporting the hypothesis of homology between shoots and leaves. Class I KNOX expression is correlated with indeterminacy in the apex and leaf of ferns, suggesting a conserved function for these genes in euphyllophytes with compound leaves.

The shoot apical meristem: an historical perspectiveThis review is one of a selection of papers published on the Special Theme of Shoot Apical Meristems.

2006 ◽  
Vol 84 (11) ◽  
pp. 1629-1633 ◽  
Author(s):  
Taylor A. Steeves
Keyword(s):  
Genetic Analysis ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Molecular Genetic ◽  
Molecular Genetic Analysis ◽  
Seed Plants ◽  
Shoot Apices ◽  
Early 19Th Century ◽  
Apical Meristems ◽  
Shoot Apical Meristems

Although much of the current investigation of shoot apical meristems is in the realm of molecular genetic analysis, it is important that previous structural and functional studies not be overlooked as essential background to these studies. Since Caspar Friedrich Wolff described the shoot apical meristem in 1759, many and varied interpretations have arisen. In the early 19th century, the apical cell was recognized in seedless vascular plants and this interpretation was extended to seed plants. However, by the 1860s, this view was replaced in seed plants by the histogen concept, which recognized meristem layers in the apical meristem giving rise to specific tissues. In 1924, the tunica–corpus interpretation of angiosperm shoot apices became widespread, the two regions being distinguished by different planes of cell division. In the 1950s, the “méristème d’attente” concept appeared in France, which argued that the central region of the apex remained essentially inactive until the onset of flowering. Meanwhile, the recognition of zonation patterns in angiosperm and gymnosperm shoot apices assumed growing functional importance. Clonal analysis based on chimeras in the meristem indicated the presence of initial cells but also their replacement. Surgical experimentation and culture of excised apices in vitro stressed the autonomy of the shoot apex and its role in shoot development. Present molecular genetic analysis may help to resolve some of the persistent questions concerning the organization and functioning of shoot apical meristems.

The branching of Trichomanes proliferum (Hymenophyllaceae)

1990 ◽  
Vol 68 (5) ◽  
pp. 1091-1097 ◽  
Author(s):  
R. Hébant-Mauri
Keyword(s):  
Key Words ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Branching Morphogenesis ◽  
General Morphology ◽  
Apical Meristems ◽  
Lateral Branching ◽  
Shoot Apical Meristems ◽  
Apical Cells ◽  
Epiphyllous Buds

The general morphology, anatomy, and meristem histology of Trichomanes proliferum were studied in order to explain the morphogenesis of this fern. As opposed to Bierhorst's conclusions, T. proliferum was found to be a typical fern with normal tetrahedral shoot apical cells and lenticular leaf apical cells. The leaf is a lateral production of the shoot apical meristem. This species is similar morphologically to other species in the genus Trichomanes: the shoot apical meristems on the creeping stolons produce "lateral systems," composed of a leaf and a bud, which are extraaxillary, as in other Trichomanes species with a creeping filiform stolon. The unique morphology of this fern is due to two supplementary branching systems: a lateral branching of the stolon, which is leafless at the fork, and an epiphyllous budding, which results in the formation of additional leaves by a different process of development. Key words: fern, branching, morphogenesis, histogenesis, epiphyllous buds.

scholarly journals Callus induction from shoot apical meristem in Triticum spelta L. and T. aestivum L.

2019 ◽  
Vol 25 ◽  
pp. 237-242
Author(s):  
A. V. Kyriienko ◽  
M. F. Parii ◽  
Yu. V. Symonenko ◽  
M. V. Kuchuk ◽  
N. L. Shcherbak
Keyword(s):  
Common Wheat ◽  
Callus Induction ◽  
Shoot Apical Meristem ◽  
Plant Material ◽  
Apical Meristem ◽  
Triticum Spelta ◽  
Apical Meristems ◽  
Shoot Apical Meristems ◽  
Positive Effect ◽  
Wheat Callus

Aim. To develop an effective protocol for callus induction from shoot apical meristem in Triticum spelta L. and T. aestivum L. Methods. Plant material: spelt “Europe” and common wheat “Bunchuk”. For this research we used shoot apical meristems from 3-days plants. For callus induction we proposed 4 media with different concentration of 2,4-D, picloram, NAA and AgNO3. Explants were growing in dark during 21 day at + 25 C. Results. Calli were transparent and mild, less than 8 mm. For callus induction positive effect were shown on media with 2,4-D and picloram. At the same time, NAA was not such effective. Conclusions. In our research was shown, that the best media for spelt callus induction should have 2 mg/l 2,4-D and 10 mg/l AgNO3. Keywords: callusogenesis, spelt (Triticum spelta L.), common wheat, callus, shoot apical meristem.

scholarly journals New Symptoms Identified in Phytoplasma-Infected Plants Reveal Extra Stages of Pathogen-Induced Meristem Fate-Derailment

2019 ◽  
Vol 32 (10) ◽  
pp. 1314-1323 ◽  
Author(s):  
Wei Wei ◽  
Robert E. Davis ◽  
Gary R. Bauchan ◽  
Yan Zhao
Keyword(s):  
Seed Production ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Flowering Plants ◽  
Multistage Process ◽  
Inflorescence Meristem ◽  
Sieve Cells ◽  
Specific Stage ◽  
Transition Research ◽  
Floral Meristems

In flowering plants, the transition of a shoot apical meristem from vegetative to reproductive destiny is a graduated, multistage process that involves sequential conversion of the vegetative meristem to an inflorescence meristem, initiation of floral meristems, emergence of flower organ primordia, and formation of floral organs. This orderly process can be derailed by phytoplasma, a bacterium that parasitizes phloem sieve cells. In a previous study, we showed that phytoplasma-induced malformation of flowers reflects stage-specific derailment of shoot apical meristems from their genetically preprogrammed reproductive destiny. Our current study unveiled new symptoms of abnormal morphogenesis, pointing to derailment of meristem transition at additional stages previously unidentified. We also found that the fate of developing meristems may be derailed even after normal termination of the floral meristem and onset of seed production. Although previous reports by others have indicated that different symptoms may be induced by different phytoplasmal effectors, the phenomenon observed in our experiment raises interesting questions as to (i) whether effectors can act at specific stages of meristem transition and (ii) whether specific floral abnormalities are attributable to meristem fate-derailment events triggered by different effectors that each act at a specific stage in meristem transition. Research addressing such questions may lead to discoveries of an array of phytoplasmal effectors.

scholarly journals Active suppression of a leaf meristem orchestrates determinate leaf growth

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
John Paul Alvarez ◽  
Chihiro Furumizu ◽  
Idan Efroni ◽  
Yuval Eshed ◽  
John L Bowman
Keyword(s):  
Arabidopsis Thaliana ◽  
Transcription Factors ◽  
Leaf Growth ◽  
Seed Plant ◽  
Plant Leaves ◽  
Active Suppression ◽  
Anatomical Features ◽  
Apical Meristems ◽  
Shoot Apical Meristems ◽  
Shoot System

Leaves are flat determinate organs derived from indeterminate shoot apical meristems. The presence of a specific leaf meristem is debated, as anatomical features typical of meristems are not present in leaves. Here we demonstrate that multiple NGATHA (NGA) and CINCINNATA-class-TCP (CIN-TCP) transcription factors act redundantly, shortly after leaf initiation, to gradually restrict the activity of a leaf meristem in Arabidopsis thaliana to marginal and basal domains, and that their absence confers persistent marginal growth to leaves, cotyledons and floral organs. Following primordia initiation, the restriction of the broadly acting leaf meristem to the margins is mediated by the juxtaposition of adaxial and abaxial domains and maintained by WOX homeobox transcription factors, whereas other marginal elaboration genes are dispensable for its maintenance. This genetic framework parallels the morphogenetic program of shoot apical meristems and may represent a relic of an ancestral shoot system from which seed plant leaves evolved.

The maize mutant narrow sheath fails to establish leaf margin identity in a meristematic domain

Development ◽  
1996 ◽  
Vol 122 (6) ◽  
pp. 1683-1691 ◽  
Author(s):  
M.J. Scanlon ◽  
R.G. Schneeberger ◽  
M. Freeling
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Leaf Shape ◽  
Specific Region ◽  
Mutant Phenotype ◽  
Leaf Margin ◽  
Knox Genes ◽  
Large Domain ◽  
Founder Cells ◽  
Plant Stature

The maize mutant narrow sheath (ns) displays a leaf shape and plant stature phenotype that suggests the preprimordial deletion of a leaf domain. The ns mutant phenotype is inherited as a recessive, duplicate-factor trait, conditioned upon homozygosity for each of the two unlinked mutations narrow sheath-1 (ns1) and narrow sheath-2 (ns2). Mutant leaves are missing a large domain including the leaf margin, and mutant internodes are shortened on the marginal side of the stem. This domain deletion extends from the internode to beyond the longitudinal mid-length of the blade, and corresponds to an alteration in the organization of a specific region of the shoot apical meristem. The premargin region of mutant founder cells fail to down-regulate expression of Knox genes, markers of nonleaf meristematic identity. Our results indicate that leaf domains may acquire identity in the meristem itself, and that the subdivision of preprimordial developmental fields into differential domains is a common feature of both plant and animal organogenesis.

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