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Stomatal pattern types, means of measuring them, advantages of each type of …


Home » Biology Articles » Botany » Stomatal patterning in angiosperms » Figures

Figures
- Stomatal patterning in angiosperms

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Fig. 1. Two-dimensional spatial patterns. (A) Random distribution; (B) Ordered distribution; (C) a magnified view from Fig. 1A ; (D), a magnified view from (B)

figure 1

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Fig. 2. Leaf tessellations from a portion of a blade panel with the margin at the lower left and the area near the midrib on the right. The position of an underlying vascular bundle is indicated as a solid line within the tessellation. Markers (cell types in this case) establish tile centers and tile edges are lines drawn midway between adjacent tile centers. (A) Tessellation based on stomata and arrested stomata (shaded) as markers. (B) Tessellation based only on stomata. (C) Relative tile distributions from the above tesselations. The relative values of tile areas are plotted as a function of count (number)

figure 2

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Fig. 3. Existing theories of stomatal patterning. (A) The inhibition theory, which was proposed by Bünning to explain patterning in dicot leaves. He postulated that mature stomata released an inhibitor that created a field in which no new stomata could arise. When growth occurred between existing stomata, the effectiveness of the inhibitory field was exceeded and new stomata could originate. The darkened cells are meristematic cells capable of becoming stomata after enough growth has occurred to separate existing stomata from one another. (B) In the cell lineage theory, which Bünning put forward to explain stomatal patterning in monocot leaves, he stated that the origin of stomata was based on previously ordered divisions and their distribution was previously designated. (C) The cell cycle theory by Charlton was advanced to explain linear groups and individual stomata in monocots. The cell cycle positions are shown in diagramatic form in the upper left. Either a single cell or a series of sister/cousin cells might all be at a similar position in the cell cycle and become specified to the same fate. Beginning at the figure's lower left a single cell and its derivatives, which tend to undergo synchronous cell divisions, create a string of cells which could all become stomata over three cell cycles

figure 3

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Fig. 4. A unified theory of stomatal patterning in angiosperms is predicated on the cell cycle theory of Charlton. In Arabidopsis, the dicot example, leaves have scattered, clonal growth, and only proliferating cells in the appropriate position of the cell division cycle (red) are capable of producing a stoma; other groups of proliferating cells (blue) are not capable of being specified to the stomatal fate. As the leaf grows, new groups of proliferating cells arise and some of the existing proliferating cells are now at the appropriate position in the cycle to become stomata. In Tradescantia, the monocot example, leaves have polarized growth and the proliferating cells are massed at the leaf base (blue). Some of these cells are at the appropriate position in the cell division cycle and become stomatal precursors (red). As the proliferating cells produce additional derivatives, the stomatal precursors divide unequally to produce a small stomatal initial (red) and a large epidermal cell. With further growth, the stomatal initials divide and differentiate as guard cells. Mature stomata first appear at the leaf tip and advance basipetally

figure 4

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