Cisgenesis
Cisgenesis, sometimes also called intragenesis, is a product designation for a category of genetically engineered plants. A variety of classification schemes have been proposed [1] that order genetically modified organisms based on the nature of introduced genotypical changes, rather than the process of genetic engineering.
Cisgenesis (from "same" and "beginning") is one term for organisms that have been engineered using a process in which genes are artificially transferred between organisms that could otherwise be conventionally bred.[2][3] Unlike in transgenesis, genes are only transferred between closely related organisms.[4] However, while future technologies may allow genomes to be directly edited within an individual organism, currently nucleic acid sequences must be isolated and introduced using the same technologies that are used to produce transgenic organisms. The term was first used in a PhD thesis by Jan Schaart of Wageningen University in 2004, discussing making strawberries less susceptible to Botrytis cinerea.
In Europe, currently, this process is governed by the same laws as transgenesis but researchers at Wageningen University in the Netherlands feel that this should be changed and regulated in the same way as conventionally bred plants. However, other scientists, writing in Nature Biotechnology, have disagreed writing, "Although lowering regulatory hurdles may increase profits in the short term, it could place the long-term potential of improved agriculture through GE in jeopardy. We would prefer to see plant molecular biologists focus their attention on developing more sophisticated methodologies such as a targeted gene knock-in strategy or genomics-assisted breeding rather than on schemes to evade regulatory mechanisms with products that are still generated by relatively crude transgenic technology."[5] In 2012 the European Food Safety Authority (EFSA) issued a report with their risk assessment of cisgenic and intragenic plants. They compared the hazards associated with plants produced by cisgenesis and intragenesis with those obtained either by conventional plant breeding techniques or transgenesis. The EFSA concluded that "similar hazards can be associated with cisgenic and conventionally bred plants, while novel hazards can be associated with intragenic and transgenic plants." They concluded that the existing European guidelines for risk assessment of food and feed from genetically modified plants and the guidelines on the environmental risk assessment of genetically modified plants were applicable for the evaluation of food and feed products derived from cisgenic and intragenic plants and did not need to be developed further.[6]
Cisgenesis and transgenesis use artificial gene transfer, which results in less extensive change to an organism's genome than mutagenesis, which was widely used before genetic engineering was developed.[7]
Some people believe that cisgenesis should not face as much regulatory oversight as genetic modification created through transgenesis as it is possible, if not practical, to transfer alleles among closely related species even by traditional crossing. The primary biological advantage of cisgenesis is that it does not disrupt favorable heterozygous states, particularly in asexually propagated crops such as potato, which do not breed true to seed. One application of cisgenesis is to create blight resistant potato plants by transferring known resistance loci wild genotypes into modern, high yielding varieties.[8]
Related classification scheme
A related classification scheme proposed by Kaare Nielsen is:[9]
| Source of genetic modification | Genetic variability via conventional breeding | Genetic distance | |
|---|---|---|---|
| Intragenic | Within genome | Possible | Low |
| Famigenic | Species in the same family | Possible | |
| Linegenic | Species in the same lineage | Impossible | |
| Transgenic | Unrelated species | Impossible | |
| Xenogenic | Laboratory-designed genes | Impossible | High |
Diagram
Note: New genotypes created with transgenic technologies also require multiple backcrossings. Furthermore, backcrossing does not account for the majority of time required to create, field test and release/commercialize a new variety.
References
- ↑ Nielsen, K. M. (2003). "Transgenic organisms—time for conceptual diversification?". Nature Biotechnology 21 (3): 227–228. doi:10.1038/nbt0303-227. PMID 12610561.
- ↑ Cisgenesis definitions cisgenesis.com
- ↑ Schubert, D.; Williams, D. (2006). "'Cisgenic' as a product designation". Nature Biotechnology 24 (11): 1327–1329; author 1329 1331–1329. doi:10.1038/nbt1106-1327. PMID 17093469.
- ↑ How the humble potato could feed the world Deborah MacKenzie, New Scientist No2667 2 August 2008 30-33
- ↑ Schubert, D.; Williams, D. (2006). "'Cisgenic' as a product designation". Nature Biotechnology 24 (11): 1327–1329; author 1329 1331–1329. doi:10.1038/nbt1106-1327. PMID 17093469.
- ↑ Staff (2012) Scientific opinion addressing the safety assessment of plants developed through cisgenesis and intragenesis EFSA Panel on Genetically Modified Organisms, Parma, Italy, Retrieved 1 October 2012
- ↑ Schouten, H.; Krens, F.; Jacobsen, E. (2006). "Do cisgenic plants warrant less stringent oversight?". Nature Biotechnology 24 (7): 753. doi:10.1038/nbt0706-753. PMID 16841052.
- ↑ Jacobsen, E.; Schouten, H. J. (2008). "Cisgenesis, a New Tool for Traditional Plant Breeding, Should be Exempted from the Regulation on Genetically Modified Organisms in a Step by Step Approach". Potato Research 51: 75–88. doi:10.1007/s11540-008-9097-y. Free version
- ↑ Nielsen, K. M. (2003). "Transgenic organisms—time for conceptual diversification?". Nature Biotechnology 21 (3): 227–228. doi:10.1038/nbt0303-227. PMID 12610561.
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