Phytoremediation

By: Tahoura SamadCOSMOS 2007Cluster 1

What is it?

Phytoremediation is the process by which various pollutants are removed from soil, water, or air by plants. (Neate)Pollutants are either organic– hydrocarbons– explosives like TNT and

RDXOr Inorganic– Heavy metals– radionucleotides

www.uga.edu/srel/Fact_Sheets/phytoremediation.htm

Different Forms of Phytoremediation

There are several different forms of phytoremediation.Rhizofiltration or phytofiltration uses plants to remove pollution from water.(Neate)

arabidopsis.info/students/dom/mainpage.html

Different Forms of Phytoremediation

phytoimmobilization-plants take up pollutants into their biomass. After the plants decompose, the contaminant is trapped in the soil or a geomat. (Kaplan)

Phytostabilization-plants take up contaminants which binds to another metal. (Neate)Even though the contaminant is not removed from the environment, it is rendered less toxic

Different Forms of Phytoremediation

Phytodegradation-plants take up contaminants into their biomass and transform them into less toxic products. (A Truly…Soils)Rhizodegradation is similar to phytodegradation except fungi and bacteria living in the soil around the roots of the plants degrade the contaminants. (A Truly…soil)

Different Forms of Phytoremediation

Phytovolatilization- After absorbing a contaminant, the plant releases it into the atmosphere (Kramer)Inside the plant, the contaminant transforms into a less toxic or more volatile substance. (Kramer)

Different Forms of Phytoremediation

Phytoextraction-the plant takes up the contaminant and stores it in its biomass.Humans harvest this biomass and dispose of it accordingly. Important plants for the phytoextraction of heavy metals are hyperaccumulators (Lasat)Hyperaccumulators- have a high tolerance to heavy metals and are able to absorb large quantities. (Lasat)

Advantages and DisadvantagesAdvantages

Costs less than other methods of remediation More accepted because its visually appealingIn situLow impactProduces less waste

(Neate)( Black)

DisadvantagesToxicity of pollutants to the plants Limited plants can be usedRisks posed to consumers of plantsTakes a long timeDependent on seasonDependent on root system of remediating plant (Neate)(Black)

Phytoremediation and Biotechnology

Biotechnology is used to increase the phytoremediating ability of plantsSometimes scientists engineer plants to alter their characteristics.– For example, they increase plants biomass, or increase its

tolerance to toxins Scientists have also engineered plants to create enzymes that aid in the absorption or degradation of other soil pollutants.

Examples of Biotechnology in Phytoremediation

Scientists engineered tree tobacco to contain a wheat gene that makes yeast resistant to cadmium. By over-expressing this gene in N. glauca (a type of tobacco), they made it more resistant to Pb.(Gisbert)Using Agrobacterium tumefaciens, the plant A. thalianawas engineered to contain XpIA, a bacterial gene that can degrade RDX . Scientists found that the engineered plants degrade RDX better then control plants.(Rylott)Scientists increased the tolerance of tobacco plants to heavy metals by engineering it to produce a polyhistidine peptide that has the ability to bind to various heavy metal ions. Created an “artificial sink” (Shingu)

Hyperaccumulators and Biotechnology

Even though hyperaccumulators are very efficient for the absorption of heavy metals, most are unsuitable for phytoextraction because they lack other characteristics important for phytoextraction such as fast growth rate and large biomass (Cherian)Scientists solve this problem via biotechnology.

Researchable QuestionIn 2004, scientists published the results of a study about T. Caerulescens(alpine pennycress) a very effective hyperaccumulator. (Apoyan)They identified the genes that are responsible for the tolerance to heavy metals and hyperaccumulative ability of the alpine pennycress. (Apoyan)

http://www.english-nature.org.uk/imagelibrary/image_details.cfm?id=100632

Researchable Question

Is it be possible to take the gene responsible for metal tolerance from T. Caerulescens and insert it into tobacco plants in order to increase tobacco’s tolerance to heavy metals? Using tobacco would be beneficial because it would have a greater biomass and faster growth.

http://www.hlasek.com/foto/thlaspi_caerulescens_8235.jpg

http://www.ces.ncsu.edu/depts/agecon/tobacco_econ/images/plant.jpg

Possible ProcedureWould be similar to our TMV-GFP lab.Insert gene of interest into TMV virusMake infectious RNA transcripts of the virusInoculate plant tobacco plant with RNA transcriptsWait for virus to progress through plantExtract viral DNA from infected leafInoculate another tobacco plantPut cadmium in soil of plant as well as soil of a control plantObserve plants over the course several weeks.

Works CitedApoyan, Ashot and Leon V. Kochian. "Indentification of Thlaspi Caerulescens Genes

That May Be Involved In Heavy Metal Hyperaccumulation and Tolerance. Characterization of a Novel Heavy Metal Transporting ATPase." Plant Physiology 2004 1-3. 17 July 2007 <http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=15516513&dopt=Abstract>

A Truly Green Way to Clean Contaminated Soils." GTI Journal. 2002. GTI . 27 Jul 2007<http://www.gastechnology.org/webroot/app/xn/xd.aspx?it=enweb&xd=4reportspubs%5C4_5gtijournal%5Csummer_2002%5Csummr02phtyofeature.xml>.

Black, Harvey. "Absorbing Possibilities:Phytoremediation." Environmental Health Perspective 103Dec. 1995 1106-1108. 23 July 2007 <http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1519251>.

Cherian , Sam and M. Margarida Oliveira. "Transgenic Plants in Phytoremediation: Recent Advances and New Possibilities." Environmental Science and Technology 2005 9377 -9390. 17 July 2007 .<http://pubs.acs.org/cgi-bin/abstract.cgi/esthag/2005/39/i24/abs/es051134l.html>

Gisbert , Carmina, Roc Ros, Antonio De Haro, David J. Walker, M. Pilar Bernal, Ramón Serrano and Juan Navarro-Aviñó. "A plant genetically modified that accumulates Pb is especially promising for phytoremediation." Biochemical and Biophysical Research Communications 303 (04 Apr 2003) 440-445. 17 July 2007 <http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WBK-485P765 1&_user=4421&_coverDate>.

Kaplan, Daniel I., Anna S. Knox, Thomas G. Hinton, Rebecca R. Sharitz, and Bruce P. Allen. "Proof-of-Concept of the Phytoimmbolization Technology for TNX Outfall Delta:Final Report." US Department of Energy 2001 13. 19 July 2007

Kramer, Ute. "Phytoremediation-Novel Approaches to Cleaning Up Polluted Soils." Current Opinion in Biotechnology 162005 133-141. 23 July 2007 <http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VRV-4FM0P34 2&_user=4421&_coverDate=04%2F30%2F2005&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000059598&_version=1&_urlVersion=0&_userid=4421&md5=084df18cb382e6ef075076e98d429d2a>.

Lasat, M.M. "Phytoextraction of Metals From Contaminated Soil: A Review of Plant/Soil/Metal interaction and Assesment of Pertinent Agronomic Issues." Journal Of Hazardous Substance Research 22000 4-5. 23 July 2007 <www.engg.ksu.edu/hsrc/JHSR/vol2no5.pdf>.

Neate, John. "Phytotechnologies: A Technical Appproach in Environmental Management." United Nations Enviroment Programme Freshwater Management Series No.7 18. 23 July 2007 <http://www.unep.or.jp/ietc/Publications/Freshwater/FMS7/index.asp>.

Rylott, Elizabeth, Rosamond G Jackson, James Edwards, Grant L Womack, Helena MB Seth-Smith, Deborah A Rathbone, Stuart E Stran and Neil C Bruce. "An explosive-degrading cytochrome P450 activity and its targeted application for the phytoremediation of RDX." Nature 24 (2006) 216-219. 17 July 2007 <http://www.nature.com/nbt/journal/v24/n2/full/nbt1184.html>.

Shingu, Yoshinori, Satoko Yokomizo, Makota Kimura, Yoshiro Ono, Isamu Yamaguchi and Hiroshi Hamamoto. "Conferring Cadmium Resistance to Mature Tobacco Plants through Metal Absorbing Particles of Tomato Mosaic Virus." Plant Biotechnology Journal (2006) 281-288. 16 July 2007 .<http://www.blackwell-synergy.com/doi/full/10.1111/j.1467-7652.2004.00083.x>