What is the Difference Between Transgenic and Cisgenic

The main difference between transgenic and cisgenic is that in a transgenic modification, the foreign genes come from an organism that is sexually incompatible with the recipient organism whereas, in a cisgenic modification, the foreign genes come from a sexually compatible donor organism. 

Transgenic and cisgenic are two types of genetic modifications classified based on the origination of the foreign genes. In a cisgenic modification, foreign genes are flanked by its own promoter and terminator sequences. However, in a transgenic modification, the regulatory sequences such as promoter can come from another organism.

Key Areas Covered

1. What is Transgenic
     – Definition, Foreign Genes, Effect
2. What is Cisgenic
     – Definition, Foreign Genes, Effect
3. What are the Similarities Between Transgenic and Cisgenic
     – Outline of Common Features
4. What is the Difference Between Transgenic and Cisgenic
     – Comparison of Key Differences

Key Terms

Cisgenic, Foreign Genes, Genetic Modification, Novel Traits, Transgenic

What is Transgenic

Transgenic is the term used to describe the genetically modified organisms with the use of foreign genes from sexually incompatible organisms. Generally, two different organisms become sexually compatible only if they belong to the same species. But here, if the recipient organism is a plant, the foreign genes come from either a plant of another species or another organism that is completely unrelated to the recipient organism. Moreover, the regulatory sequences may come from another origin, rather than from the donor organism.

Figure 1: Conventional Breeding, Transgenesis, and Cisgenesis

That means, the gene product of these transgenes introduces novel traits to the recipient organism, which do not occur in nature or traditional breeding. Thus, these novel traits may affect the fitness of the recipient organism. Besides, this can spread from the GMO organism to the wild relatives through gene flow. Hence, this can create problems in natural vegetation. Therefore, it is necessary to control the deliberate release of transgenic species under biosafety frameworks.

What is Cisgenic

Cisgenic is a term that describes the genetically modified organisms with the use of foreign genes from a sexually compatible donor organism. Which means, the foreign genes come from a donor organism in the same species of the recipient organism. These genes get introduced with the regulatory sequences such as promoter and terminator.

Figure 2: Difference Between Transgenic Sheep and Normal

However, the cisgenic transfer does not alter the gene pool of the recipient organism, and it does not introduce any novel traits. Therefore, it has no effect on the fitness of the recipient. Furthermore, the traditional breeding or the natural gene flow cannot change the fitness of the wild populations. Therefore, most people consider cisgenic organisms as safe. On the other hand, they do not affect the target group of the organisms and ecosystems.

Similarities Between Transgenic and Cisgenic

• Transgenic and cisgenic are two types of genetic modifications introduced into organisms.
• Both these methods can introduce one or more genes.
• Also, both are introduced along with regulatory sequences.

Difference Between Transgenic and Cisgenic

Definition

Transgenic refers to a modification in which the foreign genes from an unrelated organism are introduced into the recipient organism. In contrast, cisgenic refers to a genetic modification in which genes from other species do not involve.

Foreign Genes

The foreign genes come from a donor organism that is sexually incompatible with the recipient organism in transgenic modifications. However, in cisgenic modifications, the foreign genes come from an organism that is sexually compatible with the recipient organism. Thus, this is the basic difference between transgenic and cisgenic organisms. 

Regulatory Sequences

Another difference between transgenic and cisgenic is that the transgenes may contain artificial regulatory sequences. In contrast, cisgenes are introduced along with their natural promoter and terminator sequences.

Introduction of Novel Traits

While transgenic organisms express novel traits, cisgenic organisms do not express novel traits. This is a major difference between transgenic and cisgenic.

Effect on the Recipient

Furthermore, the transgenic modification can affect the fitness of the transgenic organisms while the cisgenic modification does not affect the fitness of the cisgenic organisms.

Risk Arisen with Gene Flow

Moreover, in transgenic organisms, the gene flow can affect the fitness of the wild but, in cisgenic organisms, it is not so. Hence, this also an important difference between transgenic and cisgenic.

Safety

Another difference between transgenic and cisgenic is that the transgenic organisms may be unsafe since they can reduce the fitness of the wild through gene flow. But, it is not so in cisgenic organisms as they do not affect the wild organisms.

GMO regulations

Moreover, very strict control is in place for transgenic plants while the control for cisgenic plants is less strictly.

Conclusion

Transgenic describes a type of genetic modification in which the foreign genes from an unrelated organism get introduced into a recipient organism. It produces novel traits in the recipient organism, which can be transferred to the wild through the gene flow. Also, this can affect the fitness of the wild. On the other hand, cisgenic describes a type of genetic modification in which the foreign genes from a related organism are introduced into a recipient organism. It does not produce novel traits in the recipient. Hence, it does not affect the wild. Therefore, cisgenic organisms can be considered safer than transgenic organisms. The main difference between transgenic and cisgenic is the origin of foreign genes and safety.

Reference:

1. Schouten, Henk J, Frans A Krens, and Evert Jacobsen. “Cisgenic Plants Are Similar to Traditionally Bred Plants: International Regulations for Genetically Modified Organisms Should Be Altered to Exempt Cisgenesis.” EMBO Reports7.8 (2006): 750–753. PMC. Web. 8 Oct. 2018. Available Here

Image Courtesy:

1. “Breeding transgenesis cisgenesis” By Smartse (talk) – Own work (Original text: I created this work entirely by myself.) (CC BY-SA 3.0) via Commons Wikimedia 
2. “CSIRO ScienceImage 1953 Difference Between Transgenic Sheep and Normal” By CSIRO (CC BY 3.0) via Commons Wikimedia  

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