Research Article
Impact Assessment of Mercury Accumulation and
Biochemical and Molecular Response of Mentha arvensis:
A Potential Hyperaccumulator Plant
R. Manikandan,
1
S. V. Sahi,
2
and P. Venkatachalam
1
1
Plant Genetic Engineering and Molecular Biotechnology Lab, Department of Biotechnology, Periyar University,
Salem, Tamil Nadu 636 011, India
2
Department of Biology, Western Kentucky University, 1906 College Boulevard, No. 11080, Bowling Green, KY 42101-1080, USA
Correspondence should be addressed to P. Venkatachalam; pvenkatlab@yahoo.in
Received 16 July 2014; Accepted 15 September 2014
Academic Editor: Wendong Tao
Copyright © 2015 R. Manikandan et al. his is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
he present study was focused on examining the efect of Hg oxidative stress induced physiochemical and genetic changes in M.
arvensis seedlings. he growth rate of Hg treated seedlings was decreased to 56.1% and 41.5% in roots and shoots, respectively,
compared to the control. Accumulation of Hg level in both roots and shoots was increased with increasing the concentration of Hg.
Superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities were found to be increased with increasing
the Hg concentration up to 20 mg/L; however, it was decreased at 25 mg/L Hg concentration. he POX enzyme activity was positively
correlated with Hg dose. he changes occurring in the random ampliication of ploymorphic DNA (RAPD) proiles generated from
Hg treated seedlings included variations in band intensity, disappearance of bands, and appearance of new bands compared with
the control seedlings. It was concluded that DNA polymorphisms observed with RAPD proile could be used as molecular marker
for the evaluation of heavy metal induced genotoxic efects in plant species. he present results strongly suggested that Mentha
arvensis could be used as a potential phytoremediator plant in mercury polluted environment.
1. Introduction
Mercury (Hg) heavy metal pollution is considered as a seri-
ous environmental problem throughout the world. Hg is a
persistent neurotoxin and it is the only metal in the list
of bioaccumulative chemicals of concern. Because of its
chemical properties, it exists as an elemental metal in the
form of mercuric ions and organomercury. Millions of tons of
mercury has been released into the environment as a result of
gold mining areas, industrial pollution, metal wastes, burning
of fossil fuels, and electronics [1]. In the environment, Hg
is converted by sulfate reducing bacteria to the extremely
toxic compound methyl mercury which is bioaccumulated
in the food chain [2, 3]. As heavy metals such as mercury
do not decompose in the environment, efective strategies are
needed to remove these compounds from the polluted sites.
Environmental restoration of contaminated soils with tradi-
tional physical and chemical methods is quite expensive and
environmentally invasive and demands extreme investments
of economic and technological resources [4].
Heavy metals generally cause damage to plants, either
directly or indirectly by triggering an increased level of pro-
duction of reactive oxygen species (ROS). hese ROS include
superoxide radical (O
2
∙−
), hydroxyl radical (OH
∙−
), and
hydrogen peroxide (H
2
O
2
) that are produced as byproducts
during membrane linked electron transport activities as well
as by a number of metabolic pathways. ROS damage the
cell membranes, nucleic acids, and chloroplast pigments
[5]. Plants have antioxidant systems to protect them against
oxidative damage. hese detoxiication processes are complex
and highly compartmentalized in plant cells. he level of
ROS in the plant is controlled by an antioxidative system that
consists of antioxidative enzymes like SOD, CAT, APX, POX,
and nonenzymatic low molecular mass antioxidants [6]. SOD
is a major scavenger of superoxide anion free radical, which
is converted into hydrogen peroxide (H
2
O
2
) and oxygen
Hindawi Publishing Corporation
e Scientific World Journal
Volume 2015, Article ID 715217, 10 pages
http://dx.doi.org/10.1155/2015/715217