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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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The developmental sequence showing the earliest detectable stages of primordium formation at the SAM periphery. Scanning electron micrographs (A, B), curvature plots (C, D), and side views of the reconstructed surface (E, F) were obtained from sequential replicas of the periphery of the clv3-2 inflorescence shoot apex No. 1. The side view of the reconstruction shown in (G) was obtained from the replica of the Ler inflorescence shoot apex. The time at which the replica was taken is given in the lower right corner of each micrograph. Cell outlines are overlaid on the micrographs for the region represented in the curvature maps. The colour map represents Gaussian curvature, while cross arms point to the curvature directions. Gaussian curvature is given in 10-3 μm−2. The length of cross arms is proportional to the curvature value in this direction. Arm appears in white if, in this direction, the surface is concave. A black arm points to the convex directions. The shoot apical meristem is labelled as SAM. Flower primordia are labelled by P. Primordia P1 and P2 are at the beginning of the initial bulging developmental stage. Bars=20 μm. (This figure is available in colour at JXB online.)
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fig3: The developmental sequence showing the earliest detectable stages of primordium formation at the SAM periphery. Scanning electron micrographs (A, B), curvature plots (C, D), and side views of the reconstructed surface (E, F) were obtained from sequential replicas of the periphery of the clv3-2 inflorescence shoot apex No. 1. The side view of the reconstruction shown in (G) was obtained from the replica of the Ler inflorescence shoot apex. The time at which the replica was taken is given in the lower right corner of each micrograph. Cell outlines are overlaid on the micrographs for the region represented in the curvature maps. The colour map represents Gaussian curvature, while cross arms point to the curvature directions. Gaussian curvature is given in 10-3 μm−2. The length of cross arms is proportional to the curvature value in this direction. Arm appears in white if, in this direction, the surface is concave. A black arm points to the convex directions. The shoot apical meristem is labelled as SAM. Flower primordia are labelled by P. Primordia P1 and P2 are at the beginning of the initial bulging developmental stage. Bars=20 μm. (This figure is available in colour at JXB online.)

Mentions: The shape of the periphery of the clv3-2 inflorescence SAM is very complex (Fig. 1). Therefore, in order to recognize the earliest stages of flower primordium formation the fate of a given periphery region needs to be followed in consecutive replicas of the same apex (compare P1 in Fig. 3A, E with B, F; P1 in Fig. 4A, G with C, I). Note that, in order to enable observation of young primordia in SEM, older primordia were dissected from the epoxy resin casts of these apices.


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)

The developmental sequence showing the earliest detectable stages of primordium formation at the SAM periphery. Scanning electron micrographs (A, B), curvature plots (C, D), and side views of the reconstructed surface (E, F) were obtained from sequential replicas of the periphery of the clv3-2 inflorescence shoot apex No. 1. The side view of the reconstruction shown in (G) was obtained from the replica of the Ler inflorescence shoot apex. The time at which the replica was taken is given in the lower right corner of each micrograph. Cell outlines are overlaid on the micrographs for the region represented in the curvature maps. The colour map represents Gaussian curvature, while cross arms point to the curvature directions. Gaussian curvature is given in 10-3 μm−2. The length of cross arms is proportional to the curvature value in this direction. Arm appears in white if, in this direction, the surface is concave. A black arm points to the convex directions. The shoot apical meristem is labelled as SAM. Flower primordia are labelled by P. Primordia P1 and P2 are at the beginning of the initial bulging developmental stage. 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

fig3: The developmental sequence showing the earliest detectable stages of primordium formation at the SAM periphery. Scanning electron micrographs (A, B), curvature plots (C, D), and side views of the reconstructed surface (E, F) were obtained from sequential replicas of the periphery of the clv3-2 inflorescence shoot apex No. 1. The side view of the reconstruction shown in (G) was obtained from the replica of the Ler inflorescence shoot apex. The time at which the replica was taken is given in the lower right corner of each micrograph. Cell outlines are overlaid on the micrographs for the region represented in the curvature maps. The colour map represents Gaussian curvature, while cross arms point to the curvature directions. Gaussian curvature is given in 10-3 μm−2. The length of cross arms is proportional to the curvature value in this direction. Arm appears in white if, in this direction, the surface is concave. A black arm points to the convex directions. The shoot apical meristem is labelled as SAM. Flower primordia are labelled by P. Primordia P1 and P2 are at the beginning of the initial bulging developmental stage. Bars=20 μm. (This figure is available in colour at JXB online.)
Mentions: The shape of the periphery of the clv3-2 inflorescence SAM is very complex (Fig. 1). Therefore, in order to recognize the earliest stages of flower primordium formation the fate of a given periphery region needs to be followed in consecutive replicas of the same apex (compare P1 in Fig. 3A, E with B, F; P1 in Fig. 4A, G with C, I). Note that, in order to enable observation of young primordia in SEM, older primordia were dissected from the epoxy resin casts of these apices.

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
Related in: MedlinePlus