The key difference between cisgenesis and intragenesis is that in cisgenesis, genes are introduced without doing any change to the DNA sequence, and the genes have its native promoter, introns and terminator sequences while in intragenesis, genes can be designed using genetic elements from other plants with the same sexually compatible gene pool.
Transgenesis is the genetic modification in a recipient plant with genes from any non-plant organism, or from a donor plant that is sexually incompatible with the recipient plant. Cisgenesis and intragenesis are two alternative concepts to transgenesis. Both take place between crossable species. Cisgenesis refers to the genetic modification of a recipient plant with a natural gene from a sexually compatible plant. Intragenesis, on the other hand, allows the use of new gene combinations created by in vitro rearrangements of functional genetic elements. However, both concepts are based on the use of genes from the same species or closely related species that are sexually compatible. Hence, intragenesis and cisgenesis are identical to the gene pool available for conventional breeding.
CONTENTS
1. Overview and Key Difference
2. What is Cisgenesis
3. What is Intragenesis
4. Similarities Between Cisgenesis and Intragenesis
5. Side by Side Comparison – Cisgenesis vs Intragenesis in Tabular Form
6. Summary
What is Cisgenesis?
“Cis” means ‘within the same crossable group”. Cisgenesis refers to the genetic modification of a plant with native or natural genes from the plant itself or from a crossable or sexually compatible plant. For example, a gene from one tomato variety is transferred to another tomato plant in cisgenesis using molecular techniques. Therefore, the beneficial alleles of cis-genes are transferred from a close relative to the recipient plant. Cisgenetic plants are very much similar to traditionally bred plants. It can accelerate the breeding of species with long reproductive cycles. Unlike conventional crosses, cisgenesis is fast and more efficient.
Figure 01: Breeding, Transgenesis and Cisgenesis
In cisgenesis, the gene has its native promoter, introns and terminator. Unlike in intragenesis, cisgenesis does not change the regulatory elements of the gene. As a result of cisgenesis, new traits are instilled in the recipient plant without the use of foreign genes. Hence, cisgenesis is a safe method as traditional breeding. There is no threat to the environment as well as to human health. Development of a potato variety resistant to potato blight is a representative application of cisgenesis.
What is Intragenesis?
Intragenesis is a specific type of genetic modification similar to cisgenesis. It also takes place between crossable species. However, unlike cisgenesis, intragenesis allows changing the regulatory elements of the gene. New combinations for the existing DNA sequence are done in intragenesis. Hence, the original genetic makeup is not maintained or retained. Genes are designed using genetic elements such as promoters and terminators of other crossable plants. But the coding region of the gene remains unchanged. When modifying the regulatory elements of the gene which is introduced to the recipient plant, intragenesis there are deep concerns about the safety of the environment and human health. Moreover, the vigour of the new plant can be changed due to gene influx from wild relatives.
What are the Similarities Between Cisgenesis and Intragenesis?
- Cisgenesis and intragenesis are two alternative techniques of the transgenic approach.
- Both involve the transfer of genes between crossable species/sexually compatible species.
- They do not involve recombination between non-sexually compatible organisms.
- Both do not contain linkage drag.
- There is higher public acceptance for intragenic/cisgenic crops compared to transgenic crops.
- The inheritance of vulnerable traits is also prevented by these two processes.
What is the Difference Between Cisgenesis and Intragenesis?
Cisgenesis refers to the genetic modification in which a native gene is introduced from a crossable plant to recipient plant, with its own promoter and terminator. In contrast, intragenesis refers to the genetic modification in which a gene with combined regulatory elements from other crossable plant is introduced into a recipient plant. So, this is the key difference between cisgenesis and intragenesis. In cisgenesis, the gene of interest has its own promoter and terminator while in intragenesis, the gene of interest can be combined with regulatory elements from the species itself or from a cross-compatible species. Therefore, the original genetic makeup is maintained in cisgenesis, but not in intragenesis.
Moreover, another difference between cisgenesis and intragenesis is that the cicgenesis does not change the vigour of the recipient plant, while the intragenesis can change the vigour of the new plant.
Below infographic tabulates the differences between cisgenesis and intragenesis in more detail.
Summary – Cisgenesis vs Intragenesis
Transgenesis is the transfer of genes between any species that are not sexually compatible. But cisgenesis and intragenesis involve the exclusive use of genes from the same species or from closely related species that are sexually compatible. The key difference between cisgenesis and intragenesis is that intragenesis allows the use of new gene combinations created by in vitro rearrangements of functional genetic elements, unlike in cisgenesis where the natural genes are transferred with their own regulatory elements, without doing any change to the DNA sequence.
Reference:
1. Schouten, Henk J, et al. “Cisgenic Plants Are Similar to Traditionally Bred Plants: International Regulations for Genetically Modified Organisms Should Be Altered to Exempt Cisgenesis.” EMBO Reports, U.S. National Library of Medicine, Aug. 2006, Available here.
2. Holme, Inger Baeksted et al. “Intragenesis And Cisgenesis As Alternatives To Transgenic Crop Development”. Plant Biotechnology Journal, vol 11, no. 4, 2013, pp. 395-407. Wiley, doi:10.1111/pbi.12055. Accessed 17 Sept 2020.
Image Courtesy:
1. “Breeding transgenesis cisgenesis” By Smartse at English Wikipedia – Own work (CC BY-SA 3.0) via Commons Wikimedia