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MTM CT symposium
May 2011
Geometric modeling of
plant tissue based on
X-ray computed
tomography
Els Herremans, Quang Tri Ho, Pieter Verboven, Bart Nicolaï
MeBioS, Biosystems Department
MeBioS group
• Basic research: Technology of biological systems at the
nanometer scale. These can be existing (cells,
cell organels) as well as artificial (biosensors,
biomachines) systems.
• Main research lines:
– Biosensor technology
– Biofluidics
– Computational cell biology
– Computational cell mechanics
– Physical properties of biological materials
Biofluidics in plant research
• Gas and water transport
– Maintain metabolic equilibria
• Respiration
• Photosynthesis
– Understand plant-environment
interactions
• On field
• During (longterm) storage
• Understanding through multiscale
modeling
– Diffusion-reaction modeling
– Transport properties are determined by
fruit (micro)structure
Plant structure models
• Need to incorporate structural
information in mathematical
models
• Different relevant spatial scales
• Geometric models based on X-
ray CT:– Realistic 3-D information
– ND: Internal plant structures
– High resolution imaging
– Macro- and microscale
Macrostructure
Microstructure
Nanostructures?
Braeburn apple
Plant macro-structure examples
Banana bundle Conference pear
•Various fruit geometries
•Tomohawk X-ray CT
Macrostructure: internal gas
concentrations in apple
• 3-D model of Kanzi apple obtained by Tomohawk X-ray CT
• In silico simulation of internal O2 and CO2 concentration
during storage
• Important for metabolic processes: determine fruit quality
and storage potential
Macrostructural changes: postharvest
disorders
Detection of brown and hollow tissues in apple and pear
• Disorders develop during storage due to adverse coolroom
conditions (O2, CO2, T)
• Seasonal variability, can affect up to 40% of fruits
• Great economic loss for grower
• CT system at Gasthuisberg and Tomohawk
• Ability to detect brown and hollow fruits based on X-ray absorption
Macrostructural changes: preharvest
• Development of apple from blossom to fruit
• Weekly sampling in triplicate May - Sept 2010
• Tomohawk X-ray CT
• Changes in fruit anatomy
Plant structures: more examples
Rice leaves
Rice stem (culm)
Apple seed
Messina root
SkyScan 1172
Microstructure: fruit tissue geometry
High-contrast 3-D absorption and phase
contrast imaging
• European Synchrotron Radiation Facility
(ESRF) 0,7 µm pixelsize
• Individual cell morphology, cell walls, and
3-D gas space network
• Influence on gas and water exchange
properties on microscale
• Different cultivars manifest different
microstructures (e.g. apple versus pear)
• Consequences for storability of cultivars
• Expecting similar results on NanoTom
Microstructure: in silico simulation
• Understand transport phenomena on tissue level
• Simulated intra-cellular O2 and CO2 concentration distribution in
cortex tissue of Jonagold apple in storage
• In microstructural model, lower oxygen concentrations (= critical for
development of disorders!) are obtained compared to bulk model
Microstructure: detection of brown
tissues
• Monitoring development of
browning disorder on tissue
samples in 3 regions (skin,
cortex1, cortex2)
• Monthly scans: Nov./Jan./Mar.
• SkyScan 1172
• Drastic changes in tissue
porosity
Journey to the centre of an apple fruit
Multiscale biofluidics approach: fruit geometries based on X-ray CT
data from ESRF and Tomohawk
http://www.youtube.com/watch?v=uxPRX4WKTMU
Future work
• Towards a fast detection of brown tissues in entire fruits
– Tomohawk system
– Based on radiography
– Determine number of radiographs necessary for
successful detection
– Effect of scanning at multiple energies on image contrast
– Application on a fruit grading line
• Further explore (sub)microstructures in diverse plant
tissues
– Promising first experiments with Nanotom…
Thanks to Greet for presenting.
Thank you for your attention.
Questions? Please contact us:
bart.nicolaï@biw.kuleuven.be
www.mebios.be
BIOSYSTEMS - MeBioS
Willem de Croylaan 42, 3001 Heverlee
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