CAT scans for plants?

Greg Luckman

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Feb 21, 1994, 10:07:08 PM2/21/94

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I am seeking ideas on how to better visualise root differentiation
occurring in stem cuttings of hardwood plants. At present I am fixing,
embedding and making sequential sections of stem material to look at the
pattern of differentiation in cuttings. This is a time consuming and
frustrating procedure, not least because I cannot tell if the sections I
prepare will be at the stage I need until after I have done all the
sectioning and staining, and long after I collected the sample. The other
problem with this technique is that the slides cannot be readily
translated into a three dimensional image of the tissues I am interested
in, although I presume it would be possible if I really need to.

It occurred to me that the medical world has a whole range of machines
designed to allow them look at tissues in a non-destructive, non-invasive
manner. They use ultra-sound, CAT scanners, Magnetic Resonance Imagery and
PET scanners to produce images of soft and hard tissues. I can't think of
any reason why plants could not be imaged in the same way.

My questions are:
Have any of these techniques been used to look at plant tissues?
(references please)
What are the resolution limits?
Are there any alternative methods to get the images?

Oliver Sparrow

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Feb 22, 1994, 4:09:44 AM2/22/94

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I cannot offer a reference, but I recall someone in Australia
who exploited the fact that the roots of young plants are effective
light pipes. What he did was to build a grid of conventional light
fibres through the growing medium, irradiate the growing plant
with a frequency modulated IR signal and then interrogate the fibres
with a photodiode and a phase locked loop tuned to the modulating signal.
As a further tweak, the PLL error signal was fed to an averaging box car
system which gave an overall signal to noise of phenomenal proportion.
This allowed field measurements to be taken to a 1 cm precision to a depth
of about 1.5 meters. The plant was undisturbed but the soil was, of
couse, far from its conventional structure when a 1 cm cube grid had been
lain through it!

Roots - and in particular, old roots - are not very good light pipes and
the irradiation worked best at night, when the huge gains achievable
with a box-car PLL filter could be employed free of background noise.
_________________________________________________

Oliver Sparrow
oh...@chatham.demon.co.uk

Tony Travis

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Feb 22, 1994, 1:50:59 PM2/22/94

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Greg Luckman (luc...@au.edu.utas.postoffice) wrote:
: I am seeking ideas on how to better visualise root differentiation

: occurring in stem cuttings of hardwood plants. At present I am fixing,

: [...]
: My questions are:

: Have any of these techniques been used to look at plant tissues?
: (references please)

McDougall, G.J., Goodman, B.A. and Chudek, J.A. (1992) Nuclear magnetic
resonamce (NMR) micro-imaging of stems of Linum usitatissimum, Journal of
Agricultural Science, 119, 157-164

: What are the resolution limits?

70 x 70 x 400 um voxels in their paper.

: Are there any alternative methods to get the images?

Confocal microscopy?

Tony.
--
Dr. A.J.Travis, | JANET: <a...@uk.ac.sari.rri>
Rowett Research Institute, | other: <a...@rri.sari.ac.uk>
Greenburn Road, Bucksburn, | phone: +44 (0)224 712751
Aberdeen, AB2 9SB. UK. | fax: +44 (0)224 715349

Joseph Postman

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Feb 23, 1994, 2:35:10 AM2/23/94

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In article <luckman-22...@agscience49h143.agsci.utas.edu.au> luc...@postoffice.utas.edu.au (Greg Luckman) writes:
>
>It occurred to me that the medical world has a whole range of machines
>designed to allow them look at tissues in a non-destructive, non-invasive
>manner. They use ultra-sound, CAT scanners, Magnetic Resonance Imagery and
>PET scanners to produce images of soft and hard tissues. I can't think of
>any reason why plants could not be imaged in the same way.
>
>My questions are:
>Have any of these techniques been used to look at plant tissues?
>(references please)
>What are the resolution limits?
>Are there any alternative methods to get the images?

M. Warmund et. al. used Magnetic Resonance Imaging to look at vascular
connections in apple buds grafted onto a particular rootstock:
M.R. Warmund, B. H. Barritt... 1993. J. American Society of Hort.
Science 118(1):92-96.

They cite a paper by Chien Yi Wang and Paul C. Wang on the use of Nuclear
Magnetic Resonance Imaging to nondestructively detect core breakdown in
pear fruits. 1989. HortScience 24(1):106-109. Impressive photos!

Wang and Wang cite some other interesting references:

Bottomley, P.A. et. al. 1986. NMR imaging shows water distribution and
transport in plant root systems in sity. Proc. Natl. Acad. Sci. USA 83:87-89.

Brown, J.M. et. al. 1986. In vivo magnetic resonance microscopy of
changing water content in Pelargonium hortorum roots. Plant Physiol.
82:1158-1160.

Omasa, K. et. al. 1985. NMR imaging of measuring root system and soil
water content. Env. Control Biol 23:99-102.

Wang, P.C. & S.J. Chang. 1986. Nuclear magnetic resonance imaging of wood.
Wood & Fiber Sci. 18:308-314.

I'm also interested in non-destructive methods for examining the
development of graft unions in woody plants, with the objective of early
prediction of compatible/incompatible combinations. Would like to hear
about any references or experiences in this regard.