biological, and genetic level engineering of plants make it possible to enhance the
efficiency of phytoremediating plants in remediation (Sarwar et al. 2017).
5.8 Natural Hyper-accumulator Plants
With the development of phytoremediation, hyper-accumulator plants have been
found. For example, Pteris vittata can significantly adsorb As from the soil; Zn and
Cu can be accumulated by Thlaspi caerulescens; and Sedum alfredii is also a hyperaccumulator plant for Zn, Cr, and Pb (Kim and Owens 2010).
5.9 Transgenic Plants
With the fast development of life science theory and molecular biology technology,
genetic engineering is considered one of the most effective approaches for
phytoremediation. Genetic engineering technology allows plant metallothioneins
(MTs), phytochelatins (PCs), and HM transporter genes into hyper-accumulators.
Genetic engineering technology promotes accumulation by plants: first, through
increasing the plant biomass; second, through reducing the toxicity of HMs to plants;
and third, through improving the tolerance and resistance of plants to HMs. Among
these, the third point refers to bacterial gene and enzyme expression. For example,
the incorporation of metal-binding protein genes such as mammalian
metallothionein into the tobacco plant system improves its metal tolerance level
(Maiti et al. 1991). To overcome the deleterious effect and to withstand the herbicide
application without reducing yield capacity, a new soybean species was formed by
incorporating the glyphosate-resistant gene from bacterial 5-enolpyruvylshikimate3-phosphate synthesis (Padgette et al. 1995; Delannay et al. 1995).
6 Role of Genetics for Advancement of Phytoremediation
Technology
To improve phytoremediation potential, one has to breed the potential with superior
remediation along with high biomass productivity; commonly the aspect of productivity is difficult to access via particular single gene insertion because it is controlled
by the combined effects of many genes. Many authors employed genetic engineering
by inserting squirrel genes into the plants to achieve high efficiency (Cunningham
and Ow 1996; Brown et al. 1995a, b; Chaney et al. 2000). The taller the plant, the
higher the biomass; so the efficient accumulator genes can be incorporated into taller
plants than would be wise in natural alternatives for enhancing remediation
94
M. K. Awasthi et al.
efficiency of phytoremediating plants in remediation (Sarwar et al. 2017).
5.8 Natural Hyper-accumulator Plants
With the development of phytoremediation, hyper-accumulator plants have been
found. For example, Pteris vittata can significantly adsorb As from the soil; Zn and
Cu can be accumulated by Thlaspi caerulescens; and Sedum alfredii is also a hyperaccumulator plant for Zn, Cr, and Pb (Kim and Owens 2010).
5.9 Transgenic Plants
With the fast development of life science theory and molecular biology technology,
genetic engineering is considered one of the most effective approaches for
phytoremediation. Genetic engineering technology allows plant metallothioneins
(MTs), phytochelatins (PCs), and HM transporter genes into hyper-accumulators.
Genetic engineering technology promotes accumulation by plants: first, through
increasing the plant biomass; second, through reducing the toxicity of HMs to plants;
and third, through improving the tolerance and resistance of plants to HMs. Among
these, the third point refers to bacterial gene and enzyme expression. For example,
the incorporation of metal-binding protein genes such as mammalian
metallothionein into the tobacco plant system improves its metal tolerance level
(Maiti et al. 1991). To overcome the deleterious effect and to withstand the herbicide
application without reducing yield capacity, a new soybean species was formed by
incorporating the glyphosate-resistant gene from bacterial 5-enolpyruvylshikimate3-phosphate synthesis (Padgette et al. 1995; Delannay et al. 1995).
6 Role of Genetics for Advancement of Phytoremediation
Technology
To improve phytoremediation potential, one has to breed the potential with superior
remediation along with high biomass productivity; commonly the aspect of productivity is difficult to access via particular single gene insertion because it is controlled
by the combined effects of many genes. Many authors employed genetic engineering
by inserting squirrel genes into the plants to achieve high efficiency (Cunningham
and Ow 1996; Brown et al. 1995a, b; Chaney et al. 2000). The taller the plant, the
higher the biomass; so the efficient accumulator genes can be incorporated into taller
plants than would be wise in natural alternatives for enhancing remediation
94
M. K. Awasthi et al.