Environmental Engineering Reference
In-Depth Information
Table 5.5
Potential genes involved in uptake, vacuolar sequestration, remobilization and homeostasis of heavy metals
in plants
Function
Genes involved
Annotation
Metal uptake into cells
ZIP4, ZIP6, ZIP9, ZIP10
ZIP family of metal transporters
IRT1, IRT3, ZIP7
ZIP family of metal transporters
Metal vacuolar sequestration
MTP1, MTP8, MTP11
Cation diffusion facilitator
CAX2
Ca
2+
cation antiporter
AtHMA3
P-type metal ATPase
Metal remobilization from the vacuole
NRAMP1, NRAMP3, NRAMP5
Natural resistance-associated
macrophage
Xylem loading/unloading of metal/ligands/
metal-ligand complexes
HMA4
P-type metal ATPase
FRD3
Multidrug and toxin efflux family
transporter
YSL3, YSL6, YSL7
Yellow-stripe-like transporter
Synthesis of metal ligands
NAS1, NAS2, NAS3, NAS4
Nicotinamine synthase
SAMS1, SAMS2, SAMS3
S-adenosyl-methionine synthetase
AOSA2
Cysteine synthase
Other roles in iron homeostasis
FER1, FER2
Ferritin Fe(III) binding
IREG2
Iron regulated transporter 2
At4g35830
Cytoplasmic aconitase
Stress protection/response
PDI1, PDI2
Protein disulfide isomerise 1
At1g45145
H-type thioredoxin
Homeostasis of macronutrient
PHT1
-
4
Phosphate
H1 symporter family
bZIP23, were reported to regulate the adapta-
tion to zinc deficiency and zinc homeostasis in
plants (Assun￣o et al.
2010
). Based on microar-
ray analysis on the seedlings grown on toluene-
containing media, potential genes related to the
sensing mechanism and metabolisms of toluene
are detected; Among them 202 are induced and
67 are suppressed in response to toluene, mostly
including genes encoding cytochrome P
450
s, glu-
cosyl transferases and transporters (Gao et al.
2012
). Pineau et al. (
2012
) revealed crosstalk
between Fe homeostasis and Zn tolerance in
A.
thaliana
by analysing natural variation at the
FRD3 MATE transporter locus.
nating from contrasting environments in northern
(genotype 58-861) and southern (genotype Poli)
Italy for studying the physiological and molecu-
lar response to cadmium stress, and found that
Poli was more tolerant to cadmium stress. The
study also revealed that the glutathione pathway
was also involved in the differential cadmium
tolerance of the two genotypes. He et al. (
2013
)
conducted the transcript analysis of
Populus
ￗ
ca-
nescens
response to cadmium and found 48 % of
the differentially regulated transcripts involved
in coregulation networks; among them, 43 hub
genes played a significant role in crosstalk dur-
ing distinct biological processes. These include
a putative wall-associated kinase, a GDP disso-
ciation inhibitor family protein/Rab GTPase ac-
tivator family protein, and a chloroplast sensor
kinase actively involved in signalling; the study
enhanced our understanding about the molecular
mechanism of woody plant response to heavy
metal.
Quantitative trait loci (QTL) analysis in re-
sponse to cadmium revealed a total of 16 QTL
where whole-genome microarray analysis
showed 9 cadmium-responsive genes, including
5.4.2
Populus
In recent years
Populus
tree has been used either
in natural form or as a transgenic for phytoreme-
diation. Its genes have been identified and char-
acterized as playing a role in heavy metal uptake,
but prior selection of potential hyperaccumulat-
ing genotype is required. Gaudet et al. (
2011
)
selected two
Populus nigra
L. genotypes origi-
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