Limits...
Morphogenesis at the inflorescence shoot apex of Anagallis arvensis: surface geometry and growth in comparison with the vegetative shoot.

Kwiatkowska D, Routier-Kierzkowska AL - J. Exp. Bot. (2009)

Bottom Line: Although the shapes of all the three types of primordia are very similar during their early developmental stages, areal growth rates and anisotropy of apex surface growth accompanying formation of leaf or bract primordia are profoundly different from those during formation of flower primordia.The replica method does not enable direct analysis of growth in the direction perpendicular to the apex surface (anticlinal direction).Moreover, the position of this slowly growing zone with respect to cells is not stable in the course of the meristem ontogeny.

View Article: PubMed Central - PubMed

Affiliation: Department of Biophysics and Morphogenesis of Plants, University of Silesia, Jagiellońska 28, 40-032 Katowice, Poland. Dorota.Kwiatkowska@us.edu.pl

ABSTRACT
Quantitative analysis of geometry and surface growth based on the sequential replica method is used to compare morphogenesis at the shoot apex of Anagallis arvensis in the reproductive and vegetative phases of development. Formation of three types of lateral organs takes place at the Anagallis shoot apical meristem (SAM): vegetative leaf primordia are formed during the vegetative phase and leaf-like bracts and flower primordia during the reproductive phase. Although the shapes of all the three types of primordia are very similar during their early developmental stages, areal growth rates and anisotropy of apex surface growth accompanying formation of leaf or bract primordia are profoundly different from those during formation of flower primordia. This provides an example of different modes of de novo formation of a given shape. Moreover, growth accompanying the formation of the boundary between the SAM and flower primordium is entirely different from growth at the adaxial leaf or bract primordium boundary. In the latter, areal growth rates at the future boundary are the lowest of all the apex surface, while in the former they are relatively very high. The direction of maximal growth rate is latitudinal (along the future boundary) in the case of leaf or bract primordium but meridional (across the boundary) in the case of flower. The replica method does not enable direct analysis of growth in the direction perpendicular to the apex surface (anticlinal direction). Nevertheless, the reconstructed surfaces of consecutive replicas taken from an individual apex allow general directions of SAM surface bulging accompanying primordium formation to be recognized. Precise alignment of consecutive reconstructions shows that the direction of initial bulging during the leaf or bract formation is nearly parallel to the shoot axis (upward bulging), while in the case of flower it is perpendicular to the axis (lateral bulging). In future, such 3D reconstructions can be used to assess displacement velocity fields so that growth in the anticlinal direction can be assessed. In terms of self-perpetuation, the inflorescence SAM of Anagallis differs from the SAM in the vegetative phase in that the centrally located region of slow growth is less distinct in the inflorescence SAM. Moreover, the position of this slowly growing zone with respect to cells is not stable in the course of the meristem ontogeny.

Show MeSH

Related in: MedlinePlus

Sequences of 3D reconstructions of replicas taken from three individual shoot apices of Anagallis arvensis in the vegetative developmental phase, representing consecutive stages of leaf primordium development: initial bulging, lateral expansion, and separation stages (A); the separation stage followed by the early stage of primordium curving (B); further curving of the primordium (C). Images in the upper rows of A, B and C are side views of the reconstructed apex surface obtained from consecutive replicas. The time at which the replicas were taken is given below each reconstruction; the length of line segments between the reconstructions is proportional to the time interval between the consecutive replicas. White dots labelling the profiles point to these same cells recognized on the replicas: c is the cell on the top of SAM; b is the cell at the boundary between the meristem and leaf primordium; and p is the cell on the primordium tip or flanks. Images below the ‘time segments’ are the two consecutive reconstructions overlaid using the protocol described in the text. Arrows connect the positions of each dot in the two overlaid profiles, thus pointing to the displacement directions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC2724690&req=5

fig4: Sequences of 3D reconstructions of replicas taken from three individual shoot apices of Anagallis arvensis in the vegetative developmental phase, representing consecutive stages of leaf primordium development: initial bulging, lateral expansion, and separation stages (A); the separation stage followed by the early stage of primordium curving (B); further curving of the primordium (C). Images in the upper rows of A, B and C are side views of the reconstructed apex surface obtained from consecutive replicas. The time at which the replicas were taken is given below each reconstruction; the length of line segments between the reconstructions is proportional to the time interval between the consecutive replicas. White dots labelling the profiles point to these same cells recognized on the replicas: c is the cell on the top of SAM; b is the cell at the boundary between the meristem and leaf primordium; and p is the cell on the primordium tip or flanks. Images below the ‘time segments’ are the two consecutive reconstructions overlaid using the protocol described in the text. Arrows connect the positions of each dot in the two overlaid profiles, thus pointing to the displacement directions.

Mentions: During the following stage, the separation stage, the future axil region is characterized by low areal growth rates and high anisotropy, with a latitudinal direction of maximal growth rate and nearly growth in the meridional direction (axils of P1 in Fig. 4B, C, E; P3 in Fig. 3G, H, K). In the course of this stage, areal growth rates over the remaining bract primordium surface are higher. Growth of this remaining primordium surface is less anisotropic than at the future axil (compare the adaxial and abaxial parts of P1 in Fig. 3E).


Morphogenesis at the inflorescence shoot apex of Anagallis arvensis: surface geometry and growth in comparison with the vegetative shoot.

Kwiatkowska D, Routier-Kierzkowska AL - J. Exp. Bot. (2009)

Sequences of 3D reconstructions of replicas taken from three individual shoot apices of Anagallis arvensis in the vegetative developmental phase, representing consecutive stages of leaf primordium development: initial bulging, lateral expansion, and separation stages (A); the separation stage followed by the early stage of primordium curving (B); further curving of the primordium (C). Images in the upper rows of A, B and C are side views of the reconstructed apex surface obtained from consecutive replicas. The time at which the replicas were taken is given below each reconstruction; the length of line segments between the reconstructions is proportional to the time interval between the consecutive replicas. White dots labelling the profiles point to these same cells recognized on the replicas: c is the cell on the top of SAM; b is the cell at the boundary between the meristem and leaf primordium; and p is the cell on the primordium tip or flanks. Images below the ‘time segments’ are the two consecutive reconstructions overlaid using the protocol described in the text. Arrows connect the positions of each dot in the two overlaid profiles, thus pointing to the displacement directions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2724690&req=5

fig4: Sequences of 3D reconstructions of replicas taken from three individual shoot apices of Anagallis arvensis in the vegetative developmental phase, representing consecutive stages of leaf primordium development: initial bulging, lateral expansion, and separation stages (A); the separation stage followed by the early stage of primordium curving (B); further curving of the primordium (C). Images in the upper rows of A, B and C are side views of the reconstructed apex surface obtained from consecutive replicas. The time at which the replicas were taken is given below each reconstruction; the length of line segments between the reconstructions is proportional to the time interval between the consecutive replicas. White dots labelling the profiles point to these same cells recognized on the replicas: c is the cell on the top of SAM; b is the cell at the boundary between the meristem and leaf primordium; and p is the cell on the primordium tip or flanks. Images below the ‘time segments’ are the two consecutive reconstructions overlaid using the protocol described in the text. Arrows connect the positions of each dot in the two overlaid profiles, thus pointing to the displacement directions.
Mentions: During the following stage, the separation stage, the future axil region is characterized by low areal growth rates and high anisotropy, with a latitudinal direction of maximal growth rate and nearly growth in the meridional direction (axils of P1 in Fig. 4B, C, E; P3 in Fig. 3G, H, K). In the course of this stage, areal growth rates over the remaining bract primordium surface are higher. Growth of this remaining primordium surface is less anisotropic than at the future axil (compare the adaxial and abaxial parts of P1 in Fig. 3E).

Bottom Line: Although the shapes of all the three types of primordia are very similar during their early developmental stages, areal growth rates and anisotropy of apex surface growth accompanying formation of leaf or bract primordia are profoundly different from those during formation of flower primordia.The replica method does not enable direct analysis of growth in the direction perpendicular to the apex surface (anticlinal direction).Moreover, the position of this slowly growing zone with respect to cells is not stable in the course of the meristem ontogeny.

View Article: PubMed Central - PubMed

Affiliation: Department of Biophysics and Morphogenesis of Plants, University of Silesia, Jagiellońska 28, 40-032 Katowice, Poland. Dorota.Kwiatkowska@us.edu.pl

ABSTRACT
Quantitative analysis of geometry and surface growth based on the sequential replica method is used to compare morphogenesis at the shoot apex of Anagallis arvensis in the reproductive and vegetative phases of development. Formation of three types of lateral organs takes place at the Anagallis shoot apical meristem (SAM): vegetative leaf primordia are formed during the vegetative phase and leaf-like bracts and flower primordia during the reproductive phase. Although the shapes of all the three types of primordia are very similar during their early developmental stages, areal growth rates and anisotropy of apex surface growth accompanying formation of leaf or bract primordia are profoundly different from those during formation of flower primordia. This provides an example of different modes of de novo formation of a given shape. Moreover, growth accompanying the formation of the boundary between the SAM and flower primordium is entirely different from growth at the adaxial leaf or bract primordium boundary. In the latter, areal growth rates at the future boundary are the lowest of all the apex surface, while in the former they are relatively very high. The direction of maximal growth rate is latitudinal (along the future boundary) in the case of leaf or bract primordium but meridional (across the boundary) in the case of flower. The replica method does not enable direct analysis of growth in the direction perpendicular to the apex surface (anticlinal direction). Nevertheless, the reconstructed surfaces of consecutive replicas taken from an individual apex allow general directions of SAM surface bulging accompanying primordium formation to be recognized. Precise alignment of consecutive reconstructions shows that the direction of initial bulging during the leaf or bract formation is nearly parallel to the shoot axis (upward bulging), while in the case of flower it is perpendicular to the axis (lateral bulging). In future, such 3D reconstructions can be used to assess displacement velocity fields so that growth in the anticlinal direction can be assessed. In terms of self-perpetuation, the inflorescence SAM of Anagallis differs from the SAM in the vegetative phase in that the centrally located region of slow growth is less distinct in the inflorescence SAM. Moreover, the position of this slowly growing zone with respect to cells is not stable in the course of the meristem ontogeny.

Show MeSH
Related in: MedlinePlus