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Copper localization in Cannabis
sativa grown in a copper-rich
solution
Piera Bonatti, Laura Arru, Sara Rognoni,
Micaela Baroncini, Pierdomenico Perata
University of Modena & Reggio Emilia
PHYTOREMEDIATION
The use of plants to remove heavy metals and
other pollutants from soils and waters
CELL UPTAKE AND COMPARTIMENTATION
HYSTOLOGICAL LOCALIZATION
GOLGI
TRICOMES
NUCLEUS
M
M
PLASMA
MEMBRANE
metalchaperonines
M
M
M
M
M
M
VACUOLE
M
M
xilem
APOPLASTIC
TRANSPORT
XILEMATIC TRANSPORT
M
M
Mn+
M
Mn+
M
SYMPLASTIC
TRANSPORT
MOBILIZATION
DIFFUSION
M
n+
CELL
WALL
XILEM
PARENCHIMATIC
CELLS
M
floema
M
cell.
transfer
H+-ATPase
APOPLASTIC
LOADINGH
?
M
PLASMA
MEMBRANE
CELL
WALL
SYMPLASTIC
n+
MLOADING
M
+
MALIC ACID
CITRIC ACID
ROOT UPTAKE
H
SOIL
+
M
VACUOLE
M
n+
M
M
M
M
M
Mn+
n+
M
H+-ATPase
H+
+
H
n+
M
M
M
M
CITOSOLIC
CHELATORS
PHYTOEXTRACTION OF HEAVY METALS
The most common heavy metals are:
Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sn, Zn
Are often very toxic to living organisms over a certain
concentration threshold
WHICH PLANT SPECIES FOR PHYTOEXTRACTION?
HYPERACCUMULATOR SPECIES
Represent <0,2% of all angiosperms
~400 species are hyperaccumulators
HYPERACCUMULATION THRESHOLDS:
Zn, Mn:
10 000 mG/KG
Co, Cu, Ni, Se:
1 000 mG/KG
Cd:
100 mG/KG
These thresholds are 2-3 orders of magnitude higher than in normal plant species
Alyssum serpyllifolium
Brassica juncea
HYPERACCUMULATOR
SPECIES &
PHYTOREMEDIATION
PLANTS
Thlaspi
caerulescens
Liriodendron tulipifera
Pteris vittata
WHICH PLANT SPECIES FOR PHYTOEXTRACTION?
Hyperaccumulator species must be hypertolerant
to heavy metals
Pteris vittata accumulates up to
22 000 mG/KG of arsenic, with no
phytotoxicity simptoms up to 10 000
mG/KG As
(Ma et al, Nature, 2001; Wang et al., Plant Physiol., 2002)
WHICH PLANT SPECIES FOR PHYTOEXTRACTION?
Hyperaccumulator species = low biomass?
Thlaspi caerulescens, a Zn/Cd
hyperaccumulator, produces little biomass
(2-5 t/ha)
(McGrath et al. Adv. Agronom. 2002)
Alyssum bertolonii and Berkheya coddii, Ni
hyperaccumulators, produce up to 9-22 t/ha
biomass (Robinson, 1997)
WHICH PLANT SPECIES FOR PHYTOEXTRACTION?
Can high biomass compensate for lower accumulation?
Thlaspi caerulescens
can extract 2000 g Cd / ha / year
Cannabis sativa
Can extract 126 g
Cd / ha / year
WHICH PLANT SPECIES FOR PHYTOEXTRACTION?
Hemp as a high biomass plant for phytoextraction?
Phytoxicity?
Use of fibers after
phytoextraction?
Zn toxicity on hemp plants
WHICH PLANT SPECIES FOR PHYTOEXTRACTION?
Hemp as a high biomass plant for phytoextraction?
Not hyperaccumulator
High biomass
Could be used for phytoremediation if fibers can be
commercialized
COPPER SOIL CONTAMINATION
Copper is required for the physiology of the plant
An EXCESS of copper in the soil results in phytotoxic effects
Copper is an essential cofactor for many enzymatic activities in
animals too
An EXCESS of copper is excreted by animals (liver, bile)
Genetic diseases result in altered Cu homeostasis (Wilson
disease)
Exposure to the metal copper may increase the risk of
Alzheimer's disease
COPPER SOIL CONTAMINATION
Copper sulfate is used in
agricuture, including organic
farming
Possible copper build-up in the soil
which at high levels can be
harmful to earth worm populations.
In response to such environmental
concerns copper should be
phased out of usage as soon as
possible
The aim of this work is the
localization of Cu in hemp plants
grown in a copper-enriched solution
CuSO4
Energy Dispersive X-ray Spectra (X-EDS)
STEM
Cu
LEAF EPIDERMIS
Cu
HYSTOLOGICAL LOCALIZATION OF Cu
LEAF EPIDERMIS
40 m
HYSTOLOGICAL LOCALIZATION OF Cu
TRICOMES
80 m
CITOLOGICAL LOCALIZATION OF Cu
CELL WALL
VACUOLE
PLASTID
CONCLUSIONS
Hemp grown in hydoponics accumulates cooper in the leaves (tricomes)
Copper was not detected in fibers
Further work is needed to evaluate the fibers quality from hemp grown
in open field in the presence of copper sulfate