thaliana plant, paradoxes related to As toxicity occurs under different conditions
(Chen et al. 2010), which indicates that the particular trait is not based on As
disruption in the interaction of plant and biotic stress condition. Instead of that, it
will result in plant metabolism which directly interacts with As or plant nutrients
which directly interact with As. When the proper mechanism is not known, the
growth benefit comes from As stimulation of Pi uptake (Tu and Ma 2003). There are
comparatively only limited species of plants that are As tolerant in nature. Among
them are Pteris vittata and other members of the Pteridaceae family plants that
accumulate more As (Zhao et al. 2009). The growth of the abovementioned plants is
not affected when they are exposed to high concentration of As. An important aspect
of the high accumulation of As in plant phenotype is that it restricts to shoot itself,
instead of allowing toxicity transfer to shoots. Different plants are being studied to
determine the mechanism behind the hyperaccumulation of As; unfortunately, it is
not clear how to avoid As toxicity, while highly accumulating in the leaves of the
plants (Ma et al. 2001; Pickering et al. 2006; Meharg and Hartley-Whitaker 2002).
An improved understanding of the mechanisms responsible for As resistance and
toxicity in plants needs to be studied further. For safe cropping, different
phytoremediation processes are very important, and that need to be clearly understood. A different group of plants which is resistant to As is needed for soil
remediation and rehabilitation of contaminated sites. For the area in which the
land/groundwater is contaminated by As, more As-resistant plants need to be planted
to overcome the As contamination.
6 Arsenic Effect on DNA Structure Modifications
Studies on As-induced genotoxic responses on plants and animals have been
reported (Ahmad et al. 2012; Patra et al. 2004). In biotransformation, the production
of ROS is initially linked with its genotoxicity (Dalle-Donne et al. 2006). Therefore,
the production of ROS can generate DNA–protein aberrations and can cause DNA
and oxidative base damage (Cadet and Wagner 2013), a breakdown of chromatid/
chromosome or exchange (Patra et al. 2004), apyrimidinic/apurinic sites formation
(Faita et al. 2013), DNA–protein cross-links (Woźniak and Blasiak 2003), aberrations in chromosome, exchange in sister chromatid, formation of micronuclei, and
aneuploidy and deletion (Kitchin and Wallace 2008). ROS attack on plant DNA
leads to its based modification, accordingly releasing 8-oxoguanosine (8-OHdG)
from the DNA structure (Ziech et al. 2010). 8-OHdG release leads to transversion
mutation (G:C to T:A) (Okamoto et al. 2008). In many plant tissues, the accumulation of 8-oxoguanine (8-OHdG) has been evaluated, in response to As exposure
(Crohns 2010; De Vizcaya-Ruiz et al. 2009). Similarly, As will replace P in
phosphate groups of DNA, which will affect the plant metabolism by organo-arsenic
compounds (Shipton 2014; Tofan-Lazar and Al-Abadleh 2012). Additionally, ROS
or indirectly at time of the base excision repair mechanism can cause single-strand
breaks in DNA (Kligerman et al. 2010). Zea mays and Vicia faba will raise the
12 Arsenic-Transforming Bacteria: A Potential Weapon for Arsenic-Contaminated Soil
245
(Chen et al. 2010), which indicates that the particular trait is not based on As
disruption in the interaction of plant and biotic stress condition. Instead of that, it
will result in plant metabolism which directly interacts with As or plant nutrients
which directly interact with As. When the proper mechanism is not known, the
growth benefit comes from As stimulation of Pi uptake (Tu and Ma 2003). There are
comparatively only limited species of plants that are As tolerant in nature. Among
them are Pteris vittata and other members of the Pteridaceae family plants that
accumulate more As (Zhao et al. 2009). The growth of the abovementioned plants is
not affected when they are exposed to high concentration of As. An important aspect
of the high accumulation of As in plant phenotype is that it restricts to shoot itself,
instead of allowing toxicity transfer to shoots. Different plants are being studied to
determine the mechanism behind the hyperaccumulation of As; unfortunately, it is
not clear how to avoid As toxicity, while highly accumulating in the leaves of the
plants (Ma et al. 2001; Pickering et al. 2006; Meharg and Hartley-Whitaker 2002).
An improved understanding of the mechanisms responsible for As resistance and
toxicity in plants needs to be studied further. For safe cropping, different
phytoremediation processes are very important, and that need to be clearly understood. A different group of plants which is resistant to As is needed for soil
remediation and rehabilitation of contaminated sites. For the area in which the
land/groundwater is contaminated by As, more As-resistant plants need to be planted
to overcome the As contamination.
6 Arsenic Effect on DNA Structure Modifications
Studies on As-induced genotoxic responses on plants and animals have been
reported (Ahmad et al. 2012; Patra et al. 2004). In biotransformation, the production
of ROS is initially linked with its genotoxicity (Dalle-Donne et al. 2006). Therefore,
the production of ROS can generate DNA–protein aberrations and can cause DNA
and oxidative base damage (Cadet and Wagner 2013), a breakdown of chromatid/
chromosome or exchange (Patra et al. 2004), apyrimidinic/apurinic sites formation
(Faita et al. 2013), DNA–protein cross-links (Woźniak and Blasiak 2003), aberrations in chromosome, exchange in sister chromatid, formation of micronuclei, and
aneuploidy and deletion (Kitchin and Wallace 2008). ROS attack on plant DNA
leads to its based modification, accordingly releasing 8-oxoguanosine (8-OHdG)
from the DNA structure (Ziech et al. 2010). 8-OHdG release leads to transversion
mutation (G:C to T:A) (Okamoto et al. 2008). In many plant tissues, the accumulation of 8-oxoguanine (8-OHdG) has been evaluated, in response to As exposure
(Crohns 2010; De Vizcaya-Ruiz et al. 2009). Similarly, As will replace P in
phosphate groups of DNA, which will affect the plant metabolism by organo-arsenic
compounds (Shipton 2014; Tofan-Lazar and Al-Abadleh 2012). Additionally, ROS
or indirectly at time of the base excision repair mechanism can cause single-strand
breaks in DNA (Kligerman et al. 2010). Zea mays and Vicia faba will raise the
12 Arsenic-Transforming Bacteria: A Potential Weapon for Arsenic-Contaminated Soil
245