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

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.

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Quasi-3D data representation (3D models) of outer surface and single vascular bundles and their fibre caps within the branch-stem-attachment of Dracaena marginata individual DM10.The models of the unloaded ramification are coloured blue; those of the loaded condition of the same ramification are coloured yellow. (a,b) Overlay of the 3D models of the unloaded and loaded outer surface of the ramification. Injuries caused by the cable strap (arrow 1) and the plastic tip (arrow 3) of the experimental setup become visible. A slight twisting of the entire plant as the branch bends outward is indicated (arrow 2). (c,d) Models of single vascular bundles allow a detailed display and analysis of deformations. All vascular bundles are being bent downward. The displacements differ in their magnitude and are dependent on the location of the respective vascular bundle (arrows 4–6). (e,f) Spatial orientation of the unloaded vascular bundles.
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f2: Quasi-3D data representation (3D models) of outer surface and single vascular bundles and their fibre caps within the branch-stem-attachment of Dracaena marginata individual DM10.The models of the unloaded ramification are coloured blue; those of the loaded condition of the same ramification are coloured yellow. (a,b) Overlay of the 3D models of the unloaded and loaded outer surface of the ramification. Injuries caused by the cable strap (arrow 1) and the plastic tip (arrow 3) of the experimental setup become visible. A slight twisting of the entire plant as the branch bends outward is indicated (arrow 2). (c,d) Models of single vascular bundles allow a detailed display and analysis of deformations. All vascular bundles are being bent downward. The displacements differ in their magnitude and are dependent on the location of the respective vascular bundle (arrows 4–6). (e,f) Spatial orientation of the unloaded vascular bundles.

Mentions: The branch-stem-attachment region of both individuals does not only bend downwards, it is also being twisted counter clockwise during mechanical loading (Figs 1c–f and 2a,b). The displacement caused by twisting is greater for individual DM09. The reason for the torsion seems to be a combination of the asymmetric attachment of the branch to the main stem and the experimental setup. The deformations are especially apparent when comparing the unloaded and loaded outer surface of both individuals (Figs 1c,d and 2a,b) and the meristem of the ramification of DM09 (Fig. 1e,f). The deformations are less readily detected when comparing the unloaded and loaded vascular system of the ramification of DM09 (Fig. 1g,h).


Magnetic resonance imaging reveals functional anatomy and biomechanics of a living dragon tree
Quasi-3D data representation (3D models) of outer surface and single vascular bundles and their fibre caps within the branch-stem-attachment of Dracaena marginata individual DM10.The models of the unloaded ramification are coloured blue; those of the loaded condition of the same ramification are coloured yellow. (a,b) Overlay of the 3D models of the unloaded and loaded outer surface of the ramification. Injuries caused by the cable strap (arrow 1) and the plastic tip (arrow 3) of the experimental setup become visible. A slight twisting of the entire plant as the branch bends outward is indicated (arrow 2). (c,d) Models of single vascular bundles allow a detailed display and analysis of deformations. All vascular bundles are being bent downward. The displacements differ in their magnitude and are dependent on the location of the respective vascular bundle (arrows 4–6). (e,f) 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

f2: Quasi-3D data representation (3D models) of outer surface and single vascular bundles and their fibre caps within the branch-stem-attachment of Dracaena marginata individual DM10.The models of the unloaded ramification are coloured blue; those of the loaded condition of the same ramification are coloured yellow. (a,b) Overlay of the 3D models of the unloaded and loaded outer surface of the ramification. Injuries caused by the cable strap (arrow 1) and the plastic tip (arrow 3) of the experimental setup become visible. A slight twisting of the entire plant as the branch bends outward is indicated (arrow 2). (c,d) Models of single vascular bundles allow a detailed display and analysis of deformations. All vascular bundles are being bent downward. The displacements differ in their magnitude and are dependent on the location of the respective vascular bundle (arrows 4–6). (e,f) Spatial orientation of the unloaded vascular bundles.
Mentions: The branch-stem-attachment region of both individuals does not only bend downwards, it is also being twisted counter clockwise during mechanical loading (Figs 1c–f and 2a,b). The displacement caused by twisting is greater for individual DM09. The reason for the torsion seems to be a combination of the asymmetric attachment of the branch to the main stem and the experimental setup. The deformations are especially apparent when comparing the unloaded and loaded outer surface of both individuals (Figs 1c,d and 2a,b) and the meristem of the ramification of DM09 (Fig. 1e,f). The deformations are less readily detected when comparing the unloaded and loaded vascular system of the ramification of DM09 (Fig. 1g,h).

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