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:

els.herremans@biw.kuleuven.be

pieter.verboven@biw.kuleuven.be

quangtri.ho@biw.kuleuven.be

bart.nicolaï@biw.kuleuven.be

www.mebios.be

BIOSYSTEMS - MeBioS

Willem de Croylaan 42, 3001 Heverlee