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Influence of clavata3-2 mutation on early flower development in Arabidopsis thaliana: quantitative analysis of changing geometry.

Szczesny T, Routier-Kierzkowska AL, Kwiatkowska D - J. Exp. Bot. (2008)

Bottom Line: In particular, the shape of the adaxial primordium boundary varies and seems to be related to the shape of the space available for the given primordium formation, suggesting that physical constraints play a significant role in primordium shape determination.Moreover, there is only one tunica layer in both the meristem and in the primordium until it becomes a bulge that is distinctly separated from the meristem.Starting from this stage, the anticlinal divisions predominate in subprotodermal cells, suggesting that the distribution of periclinal and anticlinal cell divisions in the early development of the flower primordium is not directly affected by the clv3-2 mutation.

View Article: PubMed Central - PubMed

Affiliation: Institute of Plant Biology, University of Wrocław, Kanonia 6/8, 50-328 Wrocław, Poland.

ABSTRACT
Early development of the flower primordium has been studied in Arabidopsis thaliana clavata3-2 (clv3-2) plants with the aid of sequential in vivo replicas and longitudinal microtome sections. Sequential replicas show that, although there is no regular phyllotaxis in the clv3-2 inflorescence shoot apex, the sites of new primordium formation are, to a large extent, predictable. The primordium always appears in a wedge-like region of the meristem periphery flanked by two older primordia. In general, stages of primordium development in clv3-2 are similar to the wild type, but quantitative geometry analysis shows that the clv3-2 primordium shape is affected even before the CLAVATA/WUSCHEL regulatory network would start to operate in the wild-type primordium. The shape of the youngest primordium in the mutant is more variable than in the wild type. In particular, the shape of the adaxial primordium boundary varies and seems to be related to the shape of the space available for the given primordium formation, suggesting that physical constraints play a significant role in primordium shape determination. The role of physical constraints is also manifested in that the shape of the primordium in the later stages, as well as the number and position of sepals, are adjusted to the available space. Longitudinal sections of clv3-2 apices show that the shape of surface cells of the meristem and young primordium is different from the wild type. Moreover, there is only one tunica layer in both the meristem and in the primordium until it becomes a bulge that is distinctly separated from the meristem. Starting from this stage, the anticlinal divisions predominate in subprotodermal cells, suggesting that the distribution of periclinal and anticlinal cell divisions in the early development of the flower primordium is not directly affected by the clv3-2 mutation.

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Flower primordium in a late bulge stage (P3) and the adjacent two primordia exhibiting the shallow crease shape (P1 and P2). Scanning electron micrographs (A–C), curvature plots (D–F), and side views of the reconstructed surface (G–I) show the portion of the periphery of the clv3-2 inflorescence shoot apex No. 1, different from the portion shown in Fig. 3. Bars=20 μm. (This figure is available in colour at JXB online.)
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fig9: Flower primordium in a late bulge stage (P3) and the adjacent two primordia exhibiting the shallow crease shape (P1 and P2). Scanning electron micrographs (A–C), curvature plots (D–F), and side views of the reconstructed surface (G–I) show the portion of the periphery of the clv3-2 inflorescence shoot apex No. 1, different from the portion shown in Fig. 3. Bars=20 μm. (This figure is available in colour at JXB online.)

Mentions: Once the adaxial primordium boundary becomes distinct, the primordium remains a bulge, of a rather regular shape for more than 24 h (Figs 7–9). During this time the primordium surface area increases while the Gaussian curvature of the primordium surface remains positive (Figs 7C, D, 8C, D, 9D–F). The shape of the primordium is first more or less hemispherical (Figs 7C, 8C). Afterwards it changes into a cone-like structure covered with a cap (Figs 7D, 9D, E). While the primordium increases, the crease at the adaxial primordium boundary deepens. The shape of the cells located at the bottom of the crease is unique, i.e. they are very narrow and elongated along the crease. The outer periclinal walls of these cells are folded (see arrows in Fig. 7E and Fig. 8F).


Influence of clavata3-2 mutation on early flower development in Arabidopsis thaliana: quantitative analysis of changing geometry.

Szczesny T, Routier-Kierzkowska AL, Kwiatkowska D - J. Exp. Bot. (2008)

Flower primordium in a late bulge stage (P3) and the adjacent two primordia exhibiting the shallow crease shape (P1 and P2). Scanning electron micrographs (A–C), curvature plots (D–F), and side views of the reconstructed surface (G–I) show the portion of the periphery of the clv3-2 inflorescence shoot apex No. 1, different from the portion shown in Fig. 3. Bars=20 μm. (This figure is available in colour at JXB online.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2651453&req=5

fig9: Flower primordium in a late bulge stage (P3) and the adjacent two primordia exhibiting the shallow crease shape (P1 and P2). Scanning electron micrographs (A–C), curvature plots (D–F), and side views of the reconstructed surface (G–I) show the portion of the periphery of the clv3-2 inflorescence shoot apex No. 1, different from the portion shown in Fig. 3. Bars=20 μm. (This figure is available in colour at JXB online.)
Mentions: Once the adaxial primordium boundary becomes distinct, the primordium remains a bulge, of a rather regular shape for more than 24 h (Figs 7–9). During this time the primordium surface area increases while the Gaussian curvature of the primordium surface remains positive (Figs 7C, D, 8C, D, 9D–F). The shape of the primordium is first more or less hemispherical (Figs 7C, 8C). Afterwards it changes into a cone-like structure covered with a cap (Figs 7D, 9D, E). While the primordium increases, the crease at the adaxial primordium boundary deepens. The shape of the cells located at the bottom of the crease is unique, i.e. they are very narrow and elongated along the crease. The outer periclinal walls of these cells are folded (see arrows in Fig. 7E and Fig. 8F).

Bottom Line: In particular, the shape of the adaxial primordium boundary varies and seems to be related to the shape of the space available for the given primordium formation, suggesting that physical constraints play a significant role in primordium shape determination.Moreover, there is only one tunica layer in both the meristem and in the primordium until it becomes a bulge that is distinctly separated from the meristem.Starting from this stage, the anticlinal divisions predominate in subprotodermal cells, suggesting that the distribution of periclinal and anticlinal cell divisions in the early development of the flower primordium is not directly affected by the clv3-2 mutation.

View Article: PubMed Central - PubMed

Affiliation: Institute of Plant Biology, University of Wrocław, Kanonia 6/8, 50-328 Wrocław, Poland.

ABSTRACT
Early development of the flower primordium has been studied in Arabidopsis thaliana clavata3-2 (clv3-2) plants with the aid of sequential in vivo replicas and longitudinal microtome sections. Sequential replicas show that, although there is no regular phyllotaxis in the clv3-2 inflorescence shoot apex, the sites of new primordium formation are, to a large extent, predictable. The primordium always appears in a wedge-like region of the meristem periphery flanked by two older primordia. In general, stages of primordium development in clv3-2 are similar to the wild type, but quantitative geometry analysis shows that the clv3-2 primordium shape is affected even before the CLAVATA/WUSCHEL regulatory network would start to operate in the wild-type primordium. The shape of the youngest primordium in the mutant is more variable than in the wild type. In particular, the shape of the adaxial primordium boundary varies and seems to be related to the shape of the space available for the given primordium formation, suggesting that physical constraints play a significant role in primordium shape determination. The role of physical constraints is also manifested in that the shape of the primordium in the later stages, as well as the number and position of sepals, are adjusted to the available space. Longitudinal sections of clv3-2 apices show that the shape of surface cells of the meristem and young primordium is different from the wild type. Moreover, there is only one tunica layer in both the meristem and in the primordium until it becomes a bulge that is distinctly separated from the meristem. Starting from this stage, the anticlinal divisions predominate in subprotodermal cells, suggesting that the distribution of periclinal and anticlinal cell divisions in the early development of the flower primordium is not directly affected by the clv3-2 mutation.

Show MeSH