Environmental Engineering Reference
In-Depth Information
combinant inbred line (RIL) populations derived
from an elite hybrid, Nongda108, and found 11
QTLs for arsenic accumulation in maize (  Zea
mays L.). In Portulaca oleracea , the peroxidase
2a (PoPRX2a) is potentially useful in the remedi-
ation of phenolic pollutants (Matsui et al. 2011 ).
In Se hyperaccumulator Astragalus racemo-
sus , 125 Se-responsive candidate genes were
identified, among which 6 responded to both
selenate and selenite treatments. In the same
study, a novel gene CEJ367 was reported to be
highly induced by both selenate (1920-fold) and
selenite (579-fold) and to provide lead to gener-
ate Se-enriched transgenic plants (Hung et al.
2012 ). HvHMA2, a P (1B)-ATPase from barley,
is highly conserved among cereals and functions
in Zn and Cd transport (Mills et al. 2012 ). So-
lanum nigrum is a cadmium (Cd) accumulator,
whereas Solanum torvum is a low Cd-accumu-
lating plant. Their comparative transcriptome
analyses revealed that increased Cd loading into
the root xylem was responsible for the differen-
tial Cd accumulation in the two Solanum species.
The higher expression of genes encoding several
metal transporters as well as antioxidant-related
genes, and several organic and amino acid bio-
synthesis/metabolism-related genes in Cd-treated
S. nigrum , indicate different responsive mecha-
nisms of the transporter genes, which under dif-
ferent metal deficiency (Fe), might be respon-
sible for differential uptake and redistribution of
the metals in the two Solanum species (Xu et al.
2012 ). A major latex-like protein is a key factor
in Cucurbitaceae family crop contamination by
persistent organic pollutants (Inui et al. 2013 ).
TaHMA2 is another gene from wheat (  Triticum
aestivum L.), which belongs to heavy metal
ATPase 2 (HMA2; Tan et al. 2013 ).
of this plant possess high potential for As accu-
mulation (Xue and Yan 2011 ). To provide some
insight on the possibility of using serpentine
adapted plants for phytoextraction of Cd, Bar-
zanti et al. ( 2011 ) investigated variations in cad-
mium tolerance, accumulation and translocation
in three Alyssum plants, and the results indicated
that the serpentine adapted population of Alys-
sum montanum showed significantly higher cad-
mium tolerance and accumulation than Alyssum
bertolonii and the ones not adapted to serpentine
soil. Plants of two aquatic macrophytes, Cerato-
phyllum demersum and Lemna gibba showed po-
tential for removing two toxic heavy metals Pb
and Cr (Abdallah 2012 ). The study also revealed
that L. gibba was more efficient at the removal
of selected heavy metals than C. demersum . L.
gibba was reported to accumulate heavy metals
without the production of toxins.
Brachiaria mutica (Forssk) Stapf was found
to have luxuriant growth with massive fibrous
roots when grown in Cr-contaminated soils
(11,170 mg/kg dry soil). These results indicated
that para grass could be used to remediate chro-
mium-contaminated soils in situ as it showed
rapid growth even with a high concentration of
Cr present (Mohanty and Patra 2012 ). Meeinkuirt
et al. ( 2012 ) analysed six tree species for phy-
toremediation abilities of Pb in sand tailings and
found that Acacia mangium with the addition of
organic fertilizer gives the best results. Adki et al.
( 2013 ) performed various studies taking Nopa-
lea cochenillifera and revealed its potential as a
chromium (VI) hyperaccumulator plant.
Amer et al. ( 2013 ) assessed the potential for
phytoremediation of heavy metals (Ni, Pb and
Zn) in three endemic Mediterranean plant spe-
cies— Atriplex halimus, Portulaca oleracea and
Medicago lupulina —and found that A. halimu-
s and M. lupulina had the potential to be used in
phytoremediation and phytostabilization. The
potential of kenaf (  Hibiscus cannabinus L.)
and corn (  Z. mays L.) for phytoremediation of
dredging sludge contaminated with trace met-
als was tested by Arbaoui et al. ( 2013 ), and after
tolerance and bioaccumulation studies, it was
found that both species could be used in phy-
toremediation. Pratas et al. ( 2013 ) assessed the
5.5
Plants Used in Phytoremediation
5.5.1
For Heavy Metals
Hydrilla verticillata (L.f.) Royle, a submerged
macrophyte widely distributed throughout the
world, has the ability to accumulate arsenic (As).
The phytofiltration studies revealed that shoots
 
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