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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 switching from the shallow crease to an early bulge stage. Its developmental stage is similar to the primordium shown in Fig. 5, but this primordium boundary with the SAM is a slightly curved crease with no apparent cavity. Scanning electron micrographs (A, B), curvature plots (C, D), and side views of the reconstructed surface (E, F) show the periphery of the clv3-2 inflorescence shoot apex No. 4. Bars=20 μm. (This figure is available in colour at JXB online.)
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fig6: Flower primordium switching from the shallow crease to an early bulge stage. Its developmental stage is similar to the primordium shown in Fig. 5, but this primordium boundary with the SAM is a slightly curved crease with no apparent cavity. Scanning electron micrographs (A, B), curvature plots (C, D), and side views of the reconstructed surface (E, F) show the periphery of the clv3-2 inflorescence shoot apex No. 4. Bars=20 μm. (This figure is available in colour at JXB online.)

Mentions: During the following 12–24 h, the primordium surface starts to bulge upward (Figs 5, 6). The abaxial part of the shallow crease changes its shape to convex (compare P1 in Fig. 5C, E with D, F). Simultaneously, on the adaxial side of the primordium, a crease-like boundary between the primordium and the SAM becomes distinct. This is a band, 2–5 cells wide, concave across the SAM margin (Figs 5B, D, 6B, D). In this respect the boundary in clv3-2 is similar to the wild type. However, the mutant boundary attains various shapes. In some cases it seems much more distinct at its centre than at the sides. This is because in the centre there is a cavity-like region between the SAM and the young primordium (compare P1 in Fig. 5C–F with P1 in Fig. 5G). In other cases the boundary depth and distinctness is more uniform along the SAM–primordium boundary (Fig. 6C–F). At this stage, the SAM slopes adjacent to the primordium are often very steep which makes the primordium appear shelf-like (Fig. 6F).


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 switching from the shallow crease to an early bulge stage. Its developmental stage is similar to the primordium shown in Fig. 5, but this primordium boundary with the SAM is a slightly curved crease with no apparent cavity. Scanning electron micrographs (A, B), curvature plots (C, D), and side views of the reconstructed surface (E, F) show the periphery of the clv3-2 inflorescence shoot apex No. 4. 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

fig6: Flower primordium switching from the shallow crease to an early bulge stage. Its developmental stage is similar to the primordium shown in Fig. 5, but this primordium boundary with the SAM is a slightly curved crease with no apparent cavity. Scanning electron micrographs (A, B), curvature plots (C, D), and side views of the reconstructed surface (E, F) show the periphery of the clv3-2 inflorescence shoot apex No. 4. Bars=20 μm. (This figure is available in colour at JXB online.)
Mentions: During the following 12–24 h, the primordium surface starts to bulge upward (Figs 5, 6). The abaxial part of the shallow crease changes its shape to convex (compare P1 in Fig. 5C, E with D, F). Simultaneously, on the adaxial side of the primordium, a crease-like boundary between the primordium and the SAM becomes distinct. This is a band, 2–5 cells wide, concave across the SAM margin (Figs 5B, D, 6B, D). In this respect the boundary in clv3-2 is similar to the wild type. However, the mutant boundary attains various shapes. In some cases it seems much more distinct at its centre than at the sides. This is because in the centre there is a cavity-like region between the SAM and the young primordium (compare P1 in Fig. 5C–F with P1 in Fig. 5G). In other cases the boundary depth and distinctness is more uniform along the SAM–primordium boundary (Fig. 6C–F). At this stage, the SAM slopes adjacent to the primordium are often very steep which makes the primordium appear shelf-like (Fig. 6F).

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