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1 Phytoremediation Protocols: An Overview 13

• Transgenic plants are reported to remove explosives residue successfully from
soil contaminated by highly toxic and mutagenic nitroglycerin, TNT, RDX,
aminodinitrotoluene (Hannink et al. 2001; Rylott et al. 2006).
• Arabidopsis thaliana transformed with an extradiol dioxygenase gene remove
2,3- dihydroxybiphenol with high efficiency (Uchida et al. 2005).

1.8 Concluding Remarks

Phytoremediation techniques exploit the unique, selective, and naturally occurring
uptake capabilities of plant root system, together with the translocation,
bioaccumulation, or detoxifying abilities of the entire plant body. There are
increasing number of reports suggesting that phytoremediation should become the
technology of choice for remediation due to its cost efficiency and ease of imple-
mentation. Although phytoremediation techniques are successfully used in many
contaminated sites in some developed countries, this technology is still in its
infancy and yet to be applied commercially. In the last decades, a number of
research projects have been carried out regarding production of suitable transgenic
plant to increase potential phytoremediation in different countries but never has
been implemented in the real contaminated sites. Restriction over field release of
such genetically manipulated plants includes increased invasiveness and decreased
genetic diversity of native plants due to interbreeding. Application of sterile clones
may solve the problem (Abhilash et al. 2009). Another major procedural constric-
tion is the insufficiency of knowledge regarding the specific enzyme involved in the
detoxification of different pollutants by plants. Therefore, increased understanding
of the enzymatic process involved in plant detoxification of diverse xenobiotics is
necessary to provide information on which gene should be engineered and that will
open new gateway for manipulating plant with superior remediation potential. In
addition, agronomic improvement ranging from traditional crop management
techniques (use of pesticides, soil amendments, fertilizer, etc.) to some precise
phytoremediation approaches such as application of plants combined with
microorganisms for efficient contaminant extraction (rhizoremediation) and
improving metal solubility in soil by using suitable chelating agents is suggested
for significant progress of phytoremediation capabilities.

Acknowledgement Authors wish to convey thanks and appreciation to Mrs. Swagata Chatterjee
for the illustrations in the chapter.

References

Abhilash PC, Jamil S, Singh N (2009) Transgenic plants for enhanced biodegradation and
phytoremediation of organic xenobiotics. Biotechnol Adv 27:474–488
Alkorta I, Hernandez-Allica J, Becerril JM, Amezaga I, Albizu I, Garbisu I (2004) Recent findings
on the phytoremediation of soils contaminated with environmentally toxic heavy metals and
metalloids such as Zn, Cd, Pb and arsenic. Rev Environ Sci Biotechnol 3:71–90