The Initiation and Determination of Leaves.

Smith, Laurie G.; Hake, Sarah

doi:10.1105/tpc.4.9.1017

Cited by 77 publications

(27 citation statements)

References 61 publications

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“…In fact, 72% of the divisions in the bottom 20 percentile occur within three cells of the edge of the meristem. If these uneven divisions are occurring in regions that eventually become flower primordia, the unevenness of the division might be due to the previously reported phenomenon of a change in the polarity of divisions within founder cells in vegetative meristems (18,19). Heuristic 2: The new cell wall passes through the center of the cell.…”

Section: Resultsmentioning

confidence: 99%

Analysis of cell division patterns in the Arabidopsis shoot apical meristem

Shapiro

Tobin

Mjolsness

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The stereotypic pattern of cell shapes in the Arabidopsis shoot apical meristem (SAM) suggests that strict rules govern the placement of new walls during cell division. When a cell in the SAM divides, a new wall is built that connects existing walls and divides the cytoplasm of the daughter cells. Because features that are determined by the placement of new walls such as cell size, shape, and number of neighbors are highly regular, rules must exist for maintaining such order. Here we present a quantitative model of these rules that incorporates different observed features of cell division. Each feature is incorporated into a "potential function" that contributes a single term to a total analog of potential energy. New cell walls are predicted to occur at locations where the potential function is minimized. Quantitative terms that represent the well-known historical rules of plant cell division, such as those given by Hofmeister, Errera, and Sachs are developed and evaluated against observed cell divisions in the epidermal layer (L1) of Arabidopsis thaliana SAM. The method is general enough to allow additional terms for nongeometric properties such as internal concentration gradients and mechanical tensile forces.cell division | computer modeling | live imaging | Arabidopsis T he Arabidopsis shoot apical meristem (SAM) is a structure at the tip of the shoot that is responsible for generating almost all of the above-ground tissue of the plant (1). Its epidermal and subepidermal cells are organized into layers with very few cells moving between layers (2, 3). When these cells expand they do so laterally, pushing other cells toward the periphery of the meristem. Division in these cells is anticlinal such that each layer remains one cell thick. The underlying mechanism determining the location of new cell walls is unknown but the qualitative properties of meristematic cell division are well documented (4-8). Perhaps the best known summary is Errera's rule, derived following observations of soap bubble formation. In the modern interpretation, the plane of division corresponds to the shortest path that will halve the mother cell. Errera, in fact, wrote that the wall would be a surface "mit constanter mittlerer Krümmung (= Minimalfläche) [with constant mean curvature (= minimal area)]" (4). Because this does not specify a location for the new cell wall, more recent authors have added to this that the mother cell divides evenly (9, 10). With this modification, Errera's rule is easily quantifiable.A second observation is Hofmeister's rule: New cell walls usually form in a plane normal to the principal axis of cell elongation (5). This rule is more difficult to quantify, because the principal axis of cell elongation is often confused with the direction of growth. Cells are asymmetrical and hence a principal direction of cell elongation can easily be calculated (e.g., the principal axis of inertia or principal component of a segmentation). The assumption is often made that because the cell is more elongated in one direction...

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Section: Resultsmentioning

confidence: 99%

Analysis of cell division patterns in the Arabidopsis shoot apical meristem

Shapiro

Tobin

Mjolsness

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…Examples of Zea mays shoot apical meristem and surrounding leaf primordia in longitudinal section. In situ localization experiments were performed using a DIG-labeled antisense probe which hybridized to knotted (Smith and Hake, 1992). Sample shown in 2A was fixed, dehydrated, and embedded using our microwave protocol.…”

Section: Resultsmentioning

confidence: 99%

Microwave Paraffin Techniques for Botanical Tissues

Schichnes

Nemson

Ruzin

2001

Springer Protocols Handbooks

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“…Several dominant mutations that altered determination patterns of maize leaf blades have been described (Smith and Hake, 1992). The most extensively characterized mutation is KNOTTED1 (Kn1), that results in the formation of pocketed outgrowth (knots) on lateral veins of blade (Freeling and Hake, 1985).…”

Section: Introductionmentioning

confidence: 99%

Dorsoventral pattern formation of tobacco leaf involves spatial expression of a tobacco homeobox gene, NTH15.

1997

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Biological function of a tobacco homeobox gene, NTH15, was studied by producing two different types of transgenic tobacco, one of which was transformed with NTH15::GUS and the other was transformed with CaMV 35S promoter::antisense NTH15. The GUS staining around shoot apical meristem (SAM) in transgenic plants with NTH15::GUS revealed that the NTH15 expression is specifically localized in the dorsal region of young leaf primordia. The transgenic plants transformed with the antisense construct lost the expression of the endogenous transcript around SAM and also showed alterations in leaf morphology. These transformants formed leaves with disorganized pinnate venation. Midribs of the malformed leaves also lost crescent-shaped vascular systems by ectopic cell vacuolization in their adaxial side. These observations suggest suppression of the NTH15 expression around SAM causes loss of dorsoventrality in midribs. Taken together with the observations of the NTH15 expression pattern, it may be important for the dorsoventral development of leaves that the NTH15 gene is expressed in the adaxial side of young leaf primordia.

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The Initiation and Determination of Leaves.

Cited by 77 publications

References 61 publications

Analysis of cell division patterns in the Arabidopsis shoot apical meristem

Analysis of cell division patterns in the Arabidopsis shoot apical meristem

Microwave Paraffin Techniques for Botanical Tissues

Dorsoventral pattern formation of tobacco leaf involves spatial expression of a tobacco homeobox gene, NTH15.

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