for their growth; now known to express under heavy metal stress (Verling 1991;
Lewis et al. 1999). HSPs not only function as molecular chaperones in normal
protein folding and assembly, but may also function that provides shield and
reconstruction of damaged proteins under the condition heavy metal stress. Apart
from this, Metal-binding proteins and peptides in plants are known to enhance metal
tolerance specifically Cd, Hg, and Pb.
A heterocyclic amino acids Proline forms fundamental part of proteins. It has
osmoprotection and metal chelator properties which enables the plant to tolerate
heavy metal stress. The antioxidative properties of Proline helps protecting the
enzymes from denaturation due to the stress and also stabilize protein, regulates
cytosolic acidity (Gajewska and Sklodowska 2007) repair the damage of chlorophyll
(Carpena et al. 2003) and provide resources of nitrogen and energy (Chandrashekhar
and Sandhyaran 1996). Under heavy metal stress, plants normally accumulate
Proline which is an indication of tolerance towards metal ion stress.
However, the situation becomes worst when plant cells are confronted with metal
ions to such an extent that may Pb to cell damage and Pb to death of the plant. To
confront with the stress, plants are known to develop molecular responses that make
them enable to tolerate the stress. For this, they possess metal transporter that are
involved in metal absorption and homeostasis; thus possess significant role in
tolerance. These include heavy metal (or CPx-type) ATPases, cation diffusion
facilitator (CDF), family proteins (Williams et al., 2000) and the Zinc-iron permease
(ZIP) family (Guerinot 2000).
1.3 Utilization of Free Floating Macrophytes
in Bioremediation of Heavy Metals
1.3.1 Mechanism of Heavy Metal Bioaccumulation in Aquatic Plants
Since Aquatic bodies are continuously being exposed to contaminants such as
pesticides, Herbicides, Fungicides, Heavy metals and other Hydrocarbon compounds due to Anthropogenic inputs, plants inhabitants of such ecosystem develop
a variety of mechanism to deal with the pollutants. The mechanism by which they
uptake, translocate and accumulate micronutrients in their cell; the same mechanism
is involved with Heavy metals from Aquatic environment. For this reason,
Phytoremediation technology has been widely used for the removal of contaminants
including heavy metals from water and soil. This mechanism follows
phytoextraction, Phyto stabilisation, rhizofilltration, and phytovolatilization (Wani
et al. 2017).
Phytoextraction
This method which is also known as phytoaccumulation is mainly employed to
remove pollutants from soil, sediment, wastewater and sludge. It involves uptake of
pollutants through roots and then translocate them in their above ground plant parts
15 Potential of Free Floating Macrophytes for Bioremediation of Heavy Metals. . .
325
Lewis et al. 1999). HSPs not only function as molecular chaperones in normal
protein folding and assembly, but may also function that provides shield and
reconstruction of damaged proteins under the condition heavy metal stress. Apart
from this, Metal-binding proteins and peptides in plants are known to enhance metal
tolerance specifically Cd, Hg, and Pb.
A heterocyclic amino acids Proline forms fundamental part of proteins. It has
osmoprotection and metal chelator properties which enables the plant to tolerate
heavy metal stress. The antioxidative properties of Proline helps protecting the
enzymes from denaturation due to the stress and also stabilize protein, regulates
cytosolic acidity (Gajewska and Sklodowska 2007) repair the damage of chlorophyll
(Carpena et al. 2003) and provide resources of nitrogen and energy (Chandrashekhar
and Sandhyaran 1996). Under heavy metal stress, plants normally accumulate
Proline which is an indication of tolerance towards metal ion stress.
However, the situation becomes worst when plant cells are confronted with metal
ions to such an extent that may Pb to cell damage and Pb to death of the plant. To
confront with the stress, plants are known to develop molecular responses that make
them enable to tolerate the stress. For this, they possess metal transporter that are
involved in metal absorption and homeostasis; thus possess significant role in
tolerance. These include heavy metal (or CPx-type) ATPases, cation diffusion
facilitator (CDF), family proteins (Williams et al., 2000) and the Zinc-iron permease
(ZIP) family (Guerinot 2000).
1.3 Utilization of Free Floating Macrophytes
in Bioremediation of Heavy Metals
1.3.1 Mechanism of Heavy Metal Bioaccumulation in Aquatic Plants
Since Aquatic bodies are continuously being exposed to contaminants such as
pesticides, Herbicides, Fungicides, Heavy metals and other Hydrocarbon compounds due to Anthropogenic inputs, plants inhabitants of such ecosystem develop
a variety of mechanism to deal with the pollutants. The mechanism by which they
uptake, translocate and accumulate micronutrients in their cell; the same mechanism
is involved with Heavy metals from Aquatic environment. For this reason,
Phytoremediation technology has been widely used for the removal of contaminants
including heavy metals from water and soil. This mechanism follows
phytoextraction, Phyto stabilisation, rhizofilltration, and phytovolatilization (Wani
et al. 2017).
Phytoextraction
This method which is also known as phytoaccumulation is mainly employed to
remove pollutants from soil, sediment, wastewater and sludge. It involves uptake of
pollutants through roots and then translocate them in their above ground plant parts
15 Potential of Free Floating Macrophytes for Bioremediation of Heavy Metals. . .
325