Phyllotactic transitions in seedlings: the case of Thuja occidentalis

Botany ◽  
2011 ◽  
Vol 89 (6) ◽  
pp. 387-396 ◽  
Author(s):  
Xiaofeng Yin ◽  
Christian Lacroix ◽  
Denis Barabé
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Divergence Angle ◽  
Apical Angle ◽  
Thuja Occidentalis ◽  
Phyllotactic Pattern ◽  
Insertion Angle ◽  
Eastern White Cedar ◽  
Leaf Insertion ◽  
Angle Parameter

The main goal of this study was to examine different phyllotactic patterns and pattern transitions in seedlings of eastern white cedar ( Thuja occidentalis L.). Four phyllotactic patterns were observed on the main stem of T. occidentalis: tetracussate, tricussate, (3, 5) spiral, and decussate. Only one phyllotactic pattern was observed on the side branches of T. occidentalis: decussate. Four types of phyllotactic pattern transition were observed: tetracussate to decussate, tetracussate to tricussate, tricussate to (3, 5) spiral, and (3, 5) spiral to decussate. For each phyllotactic pattern, the following phyllotactic parameters were examined using histological sections: divergence angle, plastochrone ratio, leaf insertion angle, parameter Г, and apical angle of the shoot apical meristem (SAM). Even though they varied widely, the phyllotactic parameters measured in T. occidentalis seem to fall within ranges observed in other plants for specific phyllotactic patterns. The results indicate that it is not possible to discriminate between the four different phyllotactic patterns observed on T. occidentalis by using the plastochrone ratio, leaf insertion angle, parameter Г, or apical angle of the SAM. In contrast to continuous transitions, where there is a good correlation between phyllotactic parameters, there was no correlation between the phyllotactic pattern (characterized by a given divergence angle) and other phyllotactic parameters in the discontinuous transitions observed in T. occidentalis.

Phyllotaxis of the palm Euterpe oleracea Mart. at the level of the shoot apical meristem

Botany ◽  
2010 ◽  
Vol 88 (5) ◽  
pp. 528-536 ◽  
Author(s):  
Denis Barabé ◽  
Laura Bourque ◽  
Xiaofeng Yin ◽  
Christian Lacroix
Keyword(s):  
Shoot Apical Meristem ◽  
Fundamental Theorem ◽  
Apical Meristem ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Divergence Angle ◽  
Euterpe Oleracea ◽  
The Mean ◽  
The Relationship ◽  
Euterpe Oleracea Mart

Previous studies on palm phyllotaxis deal mainly with the mature trunk. The goals of this study are (i) to determine the relationship between the number of parastichies, the divergence angle, and the plastochrone ratio at the level of the shoot apical meristem; (ii) to examine whether there are fluctuations in the divergence angle; (iii) to interpret the significance of phyllotactic parameters with respect to the mode of growth of the apex. The tubular base of the leaf primordium is more or less asymmetrical, and completely surrounds the shoot apical meristem. The phyllotactic system corresponds to a (2, 3) conspicuous parastichy pair. The mean divergence angle per apex varies between 126.9° ± 9.3° (mean ± SD) and 135. 8° ± 8.0°. Divergence angles for all apices fluctuate within a range of 115.89° to 157.33°. The mean plastochrone ratios between apices varies from 1.35 ± 0.18 to 1.58 ± 0.12. The plastochrone ratio at each plastochrone for all apices ranges from 1.09 to 2.00. There is no correlation between the angle of divergence and the plastochrone ratio. There is a fluctuation in the value of the divergence angle that falls within the range predicted by the fundamental theorem of phyllotaxis. The high value of the ratio of the diameter of leaf primordia over the diameter of the apex, and the long plastochrone might explain the lack of correlation between certain phyllotactic parameters.

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.

Early stages of initiation of two types of leaves in Thuja occidentalis (eastern white cedar)

2004 ◽  
Vol 82 (5) ◽  
pp. 598-606 ◽  
Author(s):  
Christian Lacroix ◽  
Denis Barabé ◽  
Bernard Jeune
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Apical Meristem ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Thuja Occidentalis ◽  
White Cedar ◽  
Early Stages ◽  
Eastern White Cedar ◽  
Scanning Electron

The developmental morphology of shoots of Thuja occidentalis L. (eastern white cedar) was investigated using scanning electron microscopy to determine the pattern of initiation of two types of leaves characteristic of higher (third and above) order branches. The shoots of eastern white cedar are bilateral in symmetry and bear leaves in an orthogonal decussate phyllotactic pattern. The shoot system is further characterized by the presence of two alternating and morphologically different pairs of leaves that constitute the basic repeating pattern of the shoot apical meristem (SAM). At maturity the dimorphism between leaf types is marked. Leaves in one plane are wide and flat in comparison with narrower and cup-shaped leaves growing in a plane perpendicular to the other leaf type. The early stages of development of each of the two types of leaves were compared using scanning electron microscopy. During the earliest visible stages of initiation (primordial crest), cup-shaped and flat leaves are very similar in morphology. As individual leaf primordia become more easily delimited as structures by the presence of a furrow between the SAM and the leaf, they differ in terms of width. As they develop further and begin to cover the SAM, the two leaf types are distinguishable morphologically (flat vs. cup shaped). Quantitative parameters such as diameter of the SAM, angle of insertion of individual leaves, and size of leaf primordia (in both a tangential and perpendicular plane) were measured on three categories of leaves: stage 1, earliest visible stage of initiation; stage 2, delineation of leaf primordium from SAM by furrowing; stage 3, leaf primordium partially covering SAM. These measurements corroborate our morphological observations, which show that during early stages of development, flat and cup-shaped leaves are morphologically similar and they diverge in their pattern of development postinitiation, especially as far as leaf width and thickness are concerned. Our results also suggest that the size and shape of the apex goes through a "repeating" cycle and is related to the type of primordium that will be initiated.Key words: Thuja occidentalis, eastern white cedar, leaf development, shoot apical meristem, phyllotaxy, leaf dimorphism.

scholarly journals Signals flowing from mature tissues to shoot apical meristem affect phyllotaxis in coniferous shoot.

2011 ◽  
Vol 75 (2) ◽  
pp. 113-121 ◽  
Author(s):  
Beata Zagórska-Marek ◽  
Alicja Banasiak
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Initiation Site ◽  
Xylem Differentiation ◽  
Spiral Pattern ◽  
Vegetative Shoot ◽  
Phyllotactic Pattern ◽  
Growth Increments ◽  
Organ Identity ◽  
Selection Of

Axial homodromy in growing shoots of perennial plants with spiral phyllotaxis is the case when the chirality of phyllotactic pattern does not change in consecutive growth increments of the same axis. In conifers such as <em>Picea</em> or<em> Abies</em> this rule is strictly observed, except for the rare cases of discontinuous phyllotactic transitions. In <em>Torreya</em>, however, the chirality changes, at random, every year. The pattern of primordia packing, executed by vegetative shoot apical meristem (SAM), depends in <em>Torreya</em> on their identity. The primordia of bud scales are initiated in the decussate and those of needles in bijugate spiral pattern. The decussate, achiral i.e. neutral pattern always precedes the formation of new spiral pattern and thus facilitates random selection of its chiral configuration. Periodic change in organ identity cannot itself be responsible for the special behavior of <em>Torreya</em>, because in other conifers it also exists. There is, however, one important difference: in Torreya, when the initiation of bud scales begins at SAM, the distance between differentiated protoxylem and the initiation site gradually increases, while in other conifers it remains constant and small. In <em>Torreya</em>, at this phase of development, the rate of xylem differentiation and the rate of organogenesis become uncoupled. Closer anatomical examination shows that the decussate pattern in a bud scale zone develops slowly suggesting gradual decrease of the putative signal flowing acropetally from differentiated protoxylem, responsible for positioning of primordia. We hypothesize that in the absence of this signal SAM starts acting autonomously, distributing primordia according to their identity only. A constant presence of the signal in other conifers assures the continuation of the same phyllotactic pattern throughout the period of bud scale formation, despite the change in organ identity.

scholarly journals Sample preparation for laser-microdissection of soybean shoot apical meristem

2012 ◽  
Vol 3 (1) ◽  
pp. 3 ◽  
Author(s):  
Chui E. Wong ◽  
Mohan B. Singh ◽  
Prem L. Bhalla
Keyword(s):  
Sample Preparation ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Laser Microdissection ◽  
Specific Cell ◽  
Legume Crop ◽  
Continuous Formation ◽  
Molecular Events ◽  
Depth Analysis ◽  
Specialized Equipment

The shoot apical meristem houses stem cells responsible for the continuous formation of aerial plant organs including leaves and stems throughout the life of plants. Laser-microdissection in combination with high-throughput technology such as next generation sequencing permits an in-depth analysis of molecular events associated with specific cell type of interest. Sample preparation is the most critical step in ensuring good quality RNA to be extracted from samples following laser-microdissection. Here, we optimized the sample preparation for a major legume crop, soybean. We used Farmer’s solution as a fixative and paraffin as the embedding medium for soybean shoot apical meristem tissue without the use of any specialized equipment. Shorter time for tissue fixation (two days) was found to be critical for the preservation of RNA in soybean shoot apical meristem. We further demonstrated the utility of this method for different tissues derived from soybean and rice. The method outlined here shall facilitate studies on crop plants involving laser-microdissection.

Somatic embryogenesis from Arabidopsis shoot apical meristem mutants

Planta ◽  
2002 ◽  
Vol 214 (6) ◽  
pp. 829-836 ◽  
Author(s):  
Andreas Mordhorst ◽  
Marijke Hartog ◽  
Mazen El Tamer ◽  
Thomas Laux ◽  
Sacco de Vries
Keyword(s):  
Somatic Embryogenesis ◽  
Shoot Apical Meristem ◽  
Apical Meristem

scholarly journals Arabidopsis Argonaute10 Specifically Sequesters miR166/165 to Regulate Shoot Apical Meristem Development

Cell ◽  
2011 ◽  
Vol 145 (2) ◽  
pp. 242-256 ◽  
Author(s):  
Hongliang Zhu ◽  
Fuqu Hu ◽  
Ronghui Wang ◽  
Xin Zhou ◽  
Sing-Hoi Sze ◽  
...  
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Meristem Development
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