scholarly journals Towards an understanding of spiral patterning in the Sargassum muticum shoot apex

2017 ◽  
Author(s):  
Marina Linardić ◽  
Siobhan A. Braybrook
Keyword(s):  
Cell Division ◽  
Brown Alga ◽  
Apical Meristem ◽  
Apical Cell ◽  
The Body ◽  
Sargassum Muticum ◽  
Control Mechanisms ◽  
Lateral Organs ◽  
Division Pattern ◽  
Underlying Mechanisms

AbstractIn plants and parenchymatous brown algae the body arises through the activity of an apical meristem (a niche of cells or a single cell). The meristem produces lateral organs in specific patterns, referred to as phyllotaxis. In plants, two different control mechanisms have been proposed – one is position-dependent and relies on morphogen accumulation at future organ sites whereas the other is a lineage-based system which links phyllotaxis to the apical cell division pattern. Here we examine the apical patterning of the brown alga, Sargassum muticum, which exhibits spiral phyllotaxis (137.5° angle) and an unlinked apical cell division pattern. The Sargassum apex presents characteristics of a self-organising system, similar to plant meristems. We were unable to correlate the plant morphogen auxin with bud positioning in Sargassum, nor could we predict cell wall softening at new bud sites. Our data suggests that in Sargassum muticum there is no connection between phyllotaxis and the apical cell division pattern indicating a position-dependent patterning mechanism may be in place. The underlying mechanisms behind the phyllotactic patterning appear to be distinct from those seen in plants.SummaryThe brown alga Sargassum muticum displays spiral phyllotaxis developed from a position-dependent self-organising mechanism, different from that understood in plants.

Branching patterns in Trichomanes and Cardiomanes (hymenophyllaceous ferns)

1984 ◽  
Vol 62 (7) ◽  
pp. 1336-1343 ◽  
Author(s):  
R. Hébant-Mauri
Keyword(s):  
Apical Meristem ◽  
Apical Cell ◽  
Relative Orientation ◽  
Vertical Position ◽  
Leaf Base ◽  
Lateral Organs ◽  
Branching Patterns ◽  
Initiation Stage ◽  
Accurate Observation ◽  
Leaf Insertion

Previous observations on Trichomanes with thick stems and axillary buds are compared with those recently obtained from species with slender stems and extraaxillary buds and also from Cardiomanes. In all species, leaves arise from typical two-sided apical cells and buds are initiated adjacent to them in cauline tissues, laterally on the apical meristem. Three different localizations of buds occur (axillary, extraaxillary, and intermediate) and result in different orientations of the whole lateral system (= leaf + bud). Each different arrangement is visible as early as the initiation stage. The leaf apical cell faces the bud initials in all cases. Growth does not interfere with relative orientation of the organs but greatly changes the vertical position of the buds, which may be borne on the stem near leaf insertion or at the leaf base. These results illustrate the necessity of accurate observation of the ontogenetic origin of lateral organs to define them.

scholarly journals Fibonacci spirals in a brown alga [Sargassum muticum (Yendo) Fensholt] and in a land plant [Arabidopsis thaliana (L.) Heynh.]: a case of morphogenetic convergence

2016 ◽  
Vol 85 (4) ◽  
Author(s):  
Alexis Peaucelle ◽  
Yves Couder
Keyword(s):  
Brown Alga ◽  
Large Scale ◽  
Strong Support ◽  
Land Plant ◽  
Sargassum Muticum ◽  
Land Plants ◽  
Lateral Organs ◽  
Unicellular Organisms ◽  
Lateral Branches ◽  
Organization Models

In this article, the morphology of a brown alga is revisited and compared to the phyllotaxis of land plants. The alga, <em>Sargassum muticum</em> (Yendo) Fensholt has a highly organized thallus with a stipe, the stem-like main axis, and hierarchically organized lateral branches of successive orders. Around each of these axes, the lateral organs: blades, side-branches, and receptacles grow in a spiral disposition. As in land plants, this organization is related to an apical mode of growth. Measurements performed along the mature differentiated axes as well as in their meristematic regions confirm the similarity of the large-scale organization of this brown alga with that of the land plants. In particular, the divergence angle between successive elements has similar values and it results from the existence around the meristem of parastichies having the same Fibonacci ordering. This is remarkable in view of the fact that brown algae (Phaeophyceae) and land plants (Embryophyta) are two clades that diverged approximately 1800 million years ago when they were both unicellular organisms. We argue that the observed similarity results from a morphogenetic convergence. This is in strong support of the genericity and robustness of self-organization models in which similar structures, here Fibonacci related spirals, can be obtained in various situations in which the genetic and physiological implementation of development can be of a different nature.

scholarly journals Sound Waves Promote Arabidopsis thaliana Root Growth by Regulating Root Phytohormone Content

2021 ◽  
Vol 22 (11) ◽  
pp. 5739
Author(s):  
Joo Yeol Kim ◽  
Hyo-Jun Lee ◽  
Jin A Kim ◽  
Mi-Jeong Jeong
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Division ◽  
Root Growth ◽  
Apical Meristem ◽  
Cell Number ◽  
Root Apical Meristem ◽  
Control Group ◽  
Auxin Signaling ◽  
Ethylene Signaling ◽  
Sound Waves

Sound waves affect plants at the biochemical, physical, and genetic levels. However, the mechanisms by which plants respond to sound waves are largely unknown. Therefore, the aim of this study was to examine the effect of sound waves on Arabidopsis thaliana growth. The results of the study showed that Arabidopsis seeds exposed to sound waves (100 and 100 + 9k Hz) for 15 h per day for 3 day had significantly longer root growth than that in the control group. The root length and cell number in the root apical meristem were significantly affected by sound waves. Furthermore, genes involved in cell division were upregulated in seedlings exposed to sound waves. Root development was affected by the concentration and activity of some phytohormones, including cytokinin and auxin. Analysis of the expression levels of genes regulating cytokinin and auxin biosynthesis and signaling showed that cytokinin and ethylene signaling genes were downregulated, while auxin signaling and biosynthesis genes were upregulated in Arabidopsis exposed to sound waves. Additionally, the cytokinin and auxin concentrations of the roots of Arabidopsis plants increased and decreased, respectively, after exposure to sound waves. Our findings suggest that sound waves are potential agricultural tools for improving crop growth performance.

scholarly journals Anti-inflammatory effects of apo-9′-fucoxanthinone from the brown alga, Sargassum muticum

2013 ◽  
Vol 21 (1) ◽  
Author(s):  
Eun-Jin Yang ◽  
Young Min Ham ◽  
Wook Jae Lee ◽  
Nam Ho Lee ◽  
Chang-Gu Hyun
Keyword(s):  
Brown Alga ◽  
Sargassum Muticum ◽  
Anti Inflammatory

scholarly journals Dissecting the Control Mechanisms for DNA Replication and Cell Division in E. coli

Cell Reports ◽  
2018 ◽  
Vol 25 (3) ◽  
pp. 761-771.e4 ◽  
Author(s):  
Gabriele Micali ◽  
Jacopo Grilli ◽  
Jacopo Marchi ◽  
Matteo Osella ◽  
Marco Cosentino Lagomarsino
Keyword(s):  
Cell Division ◽  
Dna Replication ◽  
Control Mechanisms ◽  
E Coli

scholarly journals Molecular mechanism of cytokinin-activated cell division in Arabidopsis

Science ◽  
2021 ◽  
Vol 371 (6536) ◽  
pp. 1350-1355
Author(s):  
Weibing Yang ◽  
Sandra Cortijo ◽  
Niklas Korsbo ◽  
Pawel Roszak ◽  
Katharina Schiessl ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Division ◽  
Histidine Kinase ◽  
Feedback Loop ◽  
Apical Meristem ◽  
Nuclear Accumulation ◽  
Cytokinin Signaling ◽  
Positive Feedback Loop ◽  
Nuclear Shuttling ◽  
Stimulate Cell Proliferation

Mitogens trigger cell division in animals. In plants, cytokinins, a group of phytohormones derived from adenine, stimulate cell proliferation. Cytokinin signaling is initiated by membrane-associated histidine kinase receptors and transduced through a phosphorelay system. We show that in the Arabidopsis shoot apical meristem (SAM), cytokinin regulates cell division by promoting nuclear shuttling of Myb-domain protein 3R4 (MYB3R4), a transcription factor that activates mitotic gene expression. Newly synthesized MYB3R4 protein resides predominantly in the cytoplasm. At the G2-to-M transition, rapid nuclear accumulation of MYB3R4—consistent with an associated transient peak in cytokinin concentration—feeds a positive feedback loop involving importins and initiates a transcriptional cascade that drives mitosis and cytokinesis. An engineered nuclear-restricted MYB3R4 mimics the cytokinin effects of enhanced cell proliferation and meristem growth.

scholarly journals Control mechanisms af cell division and radiation

1969 ◽  
Vol 9 (1) ◽  
pp. 21-33
Author(s):  
Yukio DOIDA
Keyword(s):  
Cell Division ◽  
Control Mechanisms

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.

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