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Magnetic resonance imaging reveals functional anatomy and biomechanics of a living dragon tree

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ABSTRACT

Magnetic resonance imaging (MRI) was used to gain in vivo insight into load-induced displacements of inner plant tissues making a non-invasive and non-destructive stress and strain analysis possible. The central aim of this study was the identification of a possible load-adapted orientation of the vascular bundles and their fibre caps as the mechanically relevant tissue in branch-stem-attachments of Dracaena marginata. The complex three-dimensional deformations that occur during mechanical loading can be analysed on the basis of quasi-three-dimensional data representations of the outer surface, the inner tissue arrangement (meristem and vascular system), and the course of single vascular bundles within the branch-stem-attachment region. In addition, deformations of vascular bundles could be quantified manually and by using digital image correlation software. This combination of qualitative and quantitative stress and strain analysis leads to an improved understanding of the functional morphology and biomechanics of D. marginata, a plant that is used as a model organism for optimizing branched technical fibre-reinforced lightweight trusses in order to increase their load bearing capacity.

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Quasi-3D data representation (3D models) of single vascular bundles and their orientation within the main stem of Dracaena marginata individual DM09.(a,b) The 3D models of single vascular bundles and their fibre caps allow a detailed display of deformations. The vascular bundles of the main stem (arrow 1) and the branch (arrow 3) bend outwards due to the applied force. An upward movement – contrary to the applied force – could be detected for the lower region of a vascular bundle in the branch-stem-attachment region (arrow 2). (c,d) Spatial orientation of the unloaded vascular bundles.
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f3: Quasi-3D data representation (3D models) of single vascular bundles and their orientation within the main stem of Dracaena marginata individual DM09.(a,b) The 3D models of single vascular bundles and their fibre caps allow a detailed display of deformations. The vascular bundles of the main stem (arrow 1) and the branch (arrow 3) bend outwards due to the applied force. An upward movement – contrary to the applied force – could be detected for the lower region of a vascular bundle in the branch-stem-attachment region (arrow 2). (c,d) Spatial orientation of the unloaded vascular bundles.

Mentions: The deformations of single vascular bundles with fibre caps differ considerably between both individuals. The vascular bundles of the main stem and those of the branch of DM09 bend according to the applied load (arrows 1 and 3 in Fig. 3a,b). The displacement is greater in the branch than in the stem. Additionally, the torsion detected for the outer surface and the meristem also holds true for the vascular bundles. Furthermore, an upward movement contrary to the applied force could be detected for vascular bundle sections located closer to the main stem within the branch-stem-attachment region (Fig. 3, arrow 2 in a and b). The vascular bundles of DM10 also bend according to the applied load (arrows 4–6 in Fig. 2c,d). However, the displacement of the vascular bundles of the main stem is hardly existent whereas the displacements of the vascular bundles of the branch are explicitly greater and exclusively directed downward. Thus, the upward movement detected for vascular bundles of individual DM09 (Fig. 3, arrow 2 in a and b) are not present for the vascular bundles of individual DM10 (Fig. 2). The slight displacement detected for the outer surface caused by twisting is barely visible for the vascular bundles of individual DM10 shown in Fig. 2.


Magnetic resonance imaging reveals functional anatomy and biomechanics of a living dragon tree
Quasi-3D data representation (3D models) of single vascular bundles and their orientation within the main stem of Dracaena marginata individual DM09.(a,b) The 3D models of single vascular bundles and their fibre caps allow a detailed display of deformations. The vascular bundles of the main stem (arrow 1) and the branch (arrow 3) bend outwards due to the applied force. An upward movement – contrary to the applied force – could be detected for the lower region of a vascular bundle in the branch-stem-attachment region (arrow 2). (c,d) Spatial orientation of the unloaded vascular bundles.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5015020&req=5

f3: Quasi-3D data representation (3D models) of single vascular bundles and their orientation within the main stem of Dracaena marginata individual DM09.(a,b) The 3D models of single vascular bundles and their fibre caps allow a detailed display of deformations. The vascular bundles of the main stem (arrow 1) and the branch (arrow 3) bend outwards due to the applied force. An upward movement – contrary to the applied force – could be detected for the lower region of a vascular bundle in the branch-stem-attachment region (arrow 2). (c,d) Spatial orientation of the unloaded vascular bundles.
Mentions: The deformations of single vascular bundles with fibre caps differ considerably between both individuals. The vascular bundles of the main stem and those of the branch of DM09 bend according to the applied load (arrows 1 and 3 in Fig. 3a,b). The displacement is greater in the branch than in the stem. Additionally, the torsion detected for the outer surface and the meristem also holds true for the vascular bundles. Furthermore, an upward movement contrary to the applied force could be detected for vascular bundle sections located closer to the main stem within the branch-stem-attachment region (Fig. 3, arrow 2 in a and b). The vascular bundles of DM10 also bend according to the applied load (arrows 4–6 in Fig. 2c,d). However, the displacement of the vascular bundles of the main stem is hardly existent whereas the displacements of the vascular bundles of the branch are explicitly greater and exclusively directed downward. Thus, the upward movement detected for vascular bundles of individual DM09 (Fig. 3, arrow 2 in a and b) are not present for the vascular bundles of individual DM10 (Fig. 2). The slight displacement detected for the outer surface caused by twisting is barely visible for the vascular bundles of individual DM10 shown in Fig. 2.

View Article: PubMed Central - PubMed

ABSTRACT

Magnetic resonance imaging (MRI) was used to gain in vivo insight into load-induced displacements of inner plant tissues making a non-invasive and non-destructive stress and strain analysis possible. The central aim of this study was the identification of a possible load-adapted orientation of the vascular bundles and their fibre caps as the mechanically relevant tissue in branch-stem-attachments of Dracaena marginata. The complex three-dimensional deformations that occur during mechanical loading can be analysed on the basis of quasi-three-dimensional data representations of the outer surface, the inner tissue arrangement (meristem and vascular system), and the course of single vascular bundles within the branch-stem-attachment region. In addition, deformations of vascular bundles could be quantified manually and by using digital image correlation software. This combination of qualitative and quantitative stress and strain analysis leads to an improved understanding of the functional morphology and biomechanics of D. marginata, a plant that is used as a model organism for optimizing branched technical fibre-reinforced lightweight trusses in order to increase their load bearing capacity.

No MeSH data available.


Related in: MedlinePlus