Apical Meristems of Roots

Clowes, F. A. L.

doi:10.1111/j.1469-185x.1959.tb01319.x

Cited by 46 publications

(49 citation statements)

References 74 publications

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“…Among pteridophytes with tetrahedral apical cells in their roots the epidermis in the few species described shows affinity solely with the cortex, as in most monocots and the Nymphaeales. This is true irrespective of whether the apical cell cuts off cells from all four faces or from only the three basiscopic faces, the functional equivalent of open and closed meristems, respectively, in angiosperms (Clowes, 1961 ;Chiang & Gifford ;1971 ;Vallade & Bugnon, 1979 ;Gifford, 1993). There are perhaps too few pteridophytes in which the roots have been examined well enough for this to be regarded as very significant in relation to the position in angiosperms shown here.…”

Section: mentioning

confidence: 63%

Pattern in root meristem development in angiosperms

2000

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Roots of angiosperms differ in the behaviour of their apical meristems, and this diversity has been studied through the patterns of differentiation in a range of families. Except for three families of the Nymphaeales, all dicotyledons derive the epidermis wholly or partially with the root cap. In closed meristems the inner cell layer of the cap complex forms the epidermis ; in open meristems, where cortex and cap are intermittently of common origin, linkages between the epidermis and the cap predominate. Roots of most monocotyledons derive the epidermis as the outer layer of the cortex. Nymphaeaceae, Cabombaceae and Barclayaceae resemble monocotyledons in this respect, and this applies even in the species with open meristems, in which a cleft forms between the cap and the rest of the apex. This feature fits with the close relationship between the Nymphaeales and monocotyledons revealed by other data. But none of the other Magnoliidae with close links to Liliidae has this type of epidermis. The Nymphaeales are also almost unique among dicotyledons in having trichoblasts in a vertical pattern. This results from transverse divisions of epidermal cells giving two conspicuously different daughters. The smaller and most densely staining one later bears a root hair. This is the way trichoblasts develop in many monocotyledons. The only other dicotyledons found with trichoblasts in vertical patterns are in the Piperaceae, though their closed meristems derive the epidermis in the normal dicotyledon pattern. All other dicotyledons that bear trichoblasts develop them in radial patterns probably related to the radial disposition of cells across the cortex. This pattern is more widespread than was previously known, though it can occur only in roots with closed meristems. In plants of both subclasses with vertical patterns of trichoblasts, it is usually the proximal daughter of the initiating mitosis which becomes the trichoblast. But it is the distal daughter in Juncaceae, Restionaceae, Cyperaceae and Poaceae. Vertical patterns differ further as to whether the atrichoblast daughters divide after initiation, thus changing the alternation of trichoblasts and atrichoblasts along a file of epidermal cells. Monocotyledons and the Nymphaeaceae can produce trichoblasts in open or closed meristems. In some embryos and root primordia the epidermis becomes discrete from cortex and cap and remains so in the meristems. This has now been found in six aquatic genera of the Liliidae, but reports of it occurring elsewhere are probably due to misinterpretation of sections. Discrete epidermises differentiate into trichoblasts and atrichoblasts in Hydrocharitaceae, but not in Araceae or Lemnaceae.

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Section: mentioning

confidence: 63%

Pattern in root meristem development in angiosperms

2000

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“…There are excellent recent reviews covering cellular, molecular and functional aspects of SAM development Vernoux et al, 2000;Traas and Doonan, 2001;Kwiatkowska, 2004). Cell division rates and cell cycle parameters in the SAM have been successfully derived by various techniques including cell counts (Lyndon, 1968), radio-labelling experiments (Clowes, 1959) and morphometric analyses combined with confocal microscopy of the SAM on fixed material (Laufs et al, 1998). Recently, approaches have been developed to enable the analysis of cell dynamics on the SAM surface by means of non-destructive analyses that preserve its 3-D structure and provide sufficient resolution to visualize individual cells (Dumais and Kwiatkowska, 2002;Kwiatkowska and Dumais, 2003;Grandjean, 2004).…”

Section: Quantitative Analysis Of Cell Division In the Shoot Apical Mmentioning

confidence: 99%

Quantitative Analyses of Cell Division in Plants

Fiorani

Beemster

2006

Plant Mol Biol

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At the molecular level regulatory interactions between cell cycle genes are being uncovered rapidly, but less progress is made in unravelling how these molecular events regulate growth processes at the level of cells and of the whole organism. The main obstacle is the absence of a set of analytical tools that are powerful enough to determine pertinent parameters and, at the same time, relatively easy to use by non-specialized laboratories. Appropriate methodology to obtain this type of data has been pioneered in the first half of the last century and is now commonly defined as 'kinematic analysis'. Unfortunately, the laborious nature of these analyses and the relatively complex numerical methods used, have limited their use to only a handful of specialized research groups. In this article we attempt to present an accessible entry to this methodology, particularly in terms of the mathematical framework. We start describing the simplest possible system, i.e., a virtually homogenous cell suspension culture. Then, we outline the analysis of dicotyledonous leaves, root tips, monocotyledonous leaves, and finally shoot apical meristems. For each of these systems we discuss the details of the calculation of cell division parameters such as cell cycle duration, size of the meristem and number of cells contained in it, which enables answering fundamental questions about the relative contribution of differences in cell production and cell size to variation in growth. In addition, we discuss the assumptions and limitations of these and alternative methodologies with the aim to facilitate the choice of appropriate analyses depending on the specific research question.

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“…As the initiation site of all major shoot structures, the SAM plays a prominent role in plant development. In angiosperms, the SAM is organized into distinct layers and zones (Brand et al ., 2001; Clowes, 1961; Steeves and Sussex, 1989). The tunica is a tissue layer, commonly one or two cells thick, that covers the surface of the meristem.…”

Section: Introductionmentioning

confidence: 99%

Analysis of surface growth in shoot apices

2002

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SummaryA salient feature of shoot meristem growth is the maintenance of distinct anatomical and morphological features despite a continuous¯ux of cells. To investigate how meristem organization is self-perpetuated, we developed a protocol for the analysis of meristem growth in 3-D. Our protocol uses a non-destructive replica method to follow the pattern of cell expansion and cell divisions on the meristem surface over several days. Algorithms to reconstruct the meristem surface and compute its curvature and rate of extension were implemented. We applied this approach to the shoot apical meristem of Anagallis arvensis and showed that a subcellular resolution of extension rates can be achieved. This is the ®rst detailed quantitative analysis of meristem geometry and surface expansion in 3-D. This new approach will be useful to connect cellular activities such as cell expansion, cell division, and differential gene expression with overall meristem morphogenesis.

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Apical Meristems of Roots

Cited by 46 publications

References 74 publications

Pattern in root meristem development in angiosperms

Pattern in root meristem development in angiosperms

Quantitative Analyses of Cell Division in Plants

Analysis of surface growth in shoot apices

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