Plants detox

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Plants detox

• Lech Kaczmarczyk
• Andrzej Rutkowski
• present

May 7th 2004
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based on J. L. Hall, Cellular mechanisms for
heavy metal detoxification and tolerance,Journal
of Experimental Botany, Vol. 53, No. 366, Jan 2002
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What influence do heavy metals (HMs)have on
plants???
?
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What influence do heavy metals (HMs)have on
plants???
Physiologically crucial for growth and surviving
(coenzymes, regulators, etc.)

• In excess toxic!
• binding to proteins sulfhydryl groups,
• enzymes inhibition,
• proteins structure deformation,
• substitution of other metals in proteins,
• leakage of other ions from cell,
• generation of free radicals and ROS.

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How do plants manage?
Prevent excess level of HMs
Coping with the excess level
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1. Ectomycorrhiza
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1. Ectomycorrhiza
Telephora terrestris
Paxillus involutus
Pinus silvestris
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1. Ectomycorrhiza - mechanisms
most HMs ? slime Cd ? cell wall vacuoles
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2. Cell wall - mechanisms
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Cell wall compounds

• silicates
• pectins

Exudates

• simple compounds
• proteins

histidine and citrate (cytrynian) chelate Ni
buckwheat (gryka) acumulates non-toxic Al-oxalate
(szczawian)
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3. Plasma membrane - elusive matter
Holcus lanatus
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3. Plasma membrane - elusive matter
Tobacco
Nt CBP4 CaM BP resistance to Ni hypersensitivity
to Pb
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3. Plasma membrane - suspected mechanism
Fact 1
underexpression
Plant HMs uptaking channels - CPx ATPases-
Nramps- Cation Diffusion Facilitator (CDF)
family- ZIP family
tolerance
overexpression
hypersensitivity
Fact 2
Fact 3
Bacterias use inducible pathways of HMs efflux
instead of mechanisms of selective uptake of
metals
Bacterias and mammals have ATPase-activity
channels, which actively pump the ions out of the
cell
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3. Plasma membrane - suspected mechanism
Conclusion Plant cell channels (especially CPx
ATPases) may play role not only in uptke but also
in efflux of HMs, yet there are no direct
evidence for that hypothesis.
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4. Heat Shock Proteins
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nucleus
cytoplasm
plasma membrane
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4. Heat Shock Proteins
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rice HM stress ? small HSPs
Lycopersicon peruvianumCd ? HSP70
Enteromorpha intestinalisCu ? HSP70
Armeria maritimaCu ? HSP17
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4. Heat Shock Proteins
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1.
2.
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5. HMs Chelators

• phytochelatines (PC)
• metallothineins (MT)
• amino acids
• organic acids

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5. HMs Chelators - phytochelatines (PC)

• (?Glu-Cys)nGly (n2 to 11),
• synthetisednon-translationallyfrom glutathione,
• induced by HMs, especialy Cd,
• chelate Cd and arsenates.

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5. HMs Chelators - phytochelatines (PC)
HMs
GSH synthesis
PC synthase
Cys, Glu, Gly
glutathione
phytochelatines
PCCd
to vacuoles
Cd
proteintransporters
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5. HMs Chelators - metallothineins (MT)
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• gene-coded proteins rich in cysteine,
• similar proteins found in mammals and yeast,
  responsible for HMs chelating,

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5. HMs Chelators - metallothineins (MT)
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MT genes
Cu
yeast
Arabidopsis
HM resistance
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5. HMs Chelators - metallothineins (MT)
L
Cu
Cd
X
MT
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5. HMs Chelators - metallothineins (MT)
L

• gene-coded proteins rich in cysteine,
• similar proteins found in mammals and yeast,
  responsible for HMs chelating,

• could be antioxidants or membrane repair
  proteins.

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5. HMs Chelators - organic and amino acids

• hypothetical ligands for HMs,
• no strong evidence.

Ni
no Hys production
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2. Cell wall - mechanisms

• simple compounds
• proteins
• silicates
• pectins

histidine and citrate (cytrynian) chelate Ni
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6. Vacuolarization
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- involving phytochelatines
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6. Vacuolarization
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Festuca rubra - vacuoles acumulate Zn

• barley (jeczmien)
• Zn, Cd and Mo are acumulated
• Ni remains in cytosol

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6. Vacuolarization
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Zn-tolerant
2.5 times more Zn in vacuoles
Silene vulgaris
isolatedvacuoles
high Zn
Zn-sensitive
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Plants detox
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Perspectives
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Our sources
J. L. Hall, Cellular mechanisms for heavy metal
detoxification and tolerance,Journal of
Experimental Botany, Vol. 53, No. 366, Jan 2002
Kopcewicz J., Lewak S., Fizjologia
roslin,Wydawnictwo Naukowe PWN, Warszawa 2002
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Photos
houby.humlak.cz/big_htlm/ plesnak_zemni_1.htm www.
dipbot.unict.it/funghi_etna/photogallery/ www.korn
er.cz/foto/Jehlicnany/ www.kulak.ac.be/facult/wet/
biologie/pb/kulakbiocampus/images/lage
planten/Holcus lanatus - Gestreepte
witbol/ www.surratt.org/herbs/herbgraphics/ www.fi
lipinolinks.com/gallery/albums/potluck/ www.floral
images.co.uk/ pic17a.htm www.bgard.sci.kun.nl/ima
ges/ us.expasy.org/sprot/ppap/ www.utoronto.ca/gre
enblattlab/ yeast.htm biology.smsu.edu/Herbarium/P
lants of the Interior Highlands/Flowers/ www.diamo
nd.ac.uk/Activity/Environment www.gut-im-bild.at/p
ages2/ Thlaspi-goesingense.htm linnaeus.nrm.se/flo
ra/mono/ poa/festu/festrub.html www.ulsamer.at/db/
stauden.html
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Thank you for your attention!
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the end