Transgenesis, Intragenesis and Cisgenesis: A Brief Review

The authors briefly reviewed some aspects of Transgenesis, Intragenesis and Cisgenesis, their differences and similarities.

1. Transgenesis, Intragenesis & Cisgenesis
I A B r i e f R e v i e w I

2. Overview
●Introduction
●Conventional plant breeding
●Transgenesis
●Cisgenesis
●Cisgenesis v/s Transgenesis
●Cisgenesis v/s Conventional breeding
●Intragenesis
●Cisgenesis v/s Intragenesis
●Cisgenesis, Intragenesis and Transgenesis
●Transgenesis, Intragenesis, Cisgenesis and Conventional
breeding
●Conclusion
●References

3. Introduction
Problems related to agriculture & food
security have led to the development of
new technologies to curb those & meet
the ever-increasing food demand.
In the past
Conventional
breeding
New
technologies
Presently
Cisgenesis
Transgenesis
Intragenesis
Moreover, they hold the potential to produce crops with better,
improved agricultural traits & of consumer acceptability.

B
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4. Conventional Plant Breeding
Plant breeding is the science of improving
genetic properties of cultivated crops.
Conventional techniques were:

1.F1 hybrid breeding (hybridisation)
2.Bridge crossing
3.Repeated backcrossing

1
3
2

5. Conventional Plant Breeding
4. Cut Style technique






Other techniques such as combination breeding, mutation
induction and anther/microspore culture were developed and are
still in use.
5. Grafting on the style

6. Transgenesis
Genetic modification by either the expression of a foreign gene or
the suppression of an endogenous protein to modify a function.
Genes/DNA can be moved between any species.

Examples:
●First GMO commercialised (1994): Flavr Savr™ tomato
○Longer shelf life (antisense RNA regulating the level of
polygalacturonase enzyme involved in fruit ripening)
○In 1996, soybean, canola, cotton and maize, herbicide-
resistant transgenic lines were introduced to simplify weed-
control practices.




(Espinoza et al., 2013)




Although it’s a promising tool for agriculture and enhancing
economic development, major concern for public acceptance is an
important factor.

7. Cisgenesis
Schouten et al. (2006) definition of ‘cisgenic plant’:
“A crop plant that has been genetically modified with one or more
genes (containing introns and flanking regions such as native
promoter and terminator regions in a sense orientation) isolated from
a crossable donor plant”.

That is:
●It has all the necessary regulatory elements of a natural gene (a
perfect copy).

(Espinoza et al., 2013)
Examples (Telem et al., 2013):
-Cisgenic apple which confer scab resistance
-Cisgenic barley with improved phytase activity

8. Cisgenesis VS Transgenesis
●Cisgenesis: transfer of genes between crossable species or
the plant itself
○same techniques as in traditional plant breeding can be
used, and as safe
○new traits without use of foreign genes
○no environmental risks
●Transgenesis: transfer between non-crossable species
○Recombination used
○Regulations concerning GMOs are based on transgenes
only: thus strict
○Foreign genes ( bacteria, sexually incompatible species)

(Hou et al., 2014)

9. Cisgenesis VS Transgenesis
Hence, there is a need to differentiate between the two to
avoid problems like:
●Delaying research & application of improved plant varieties.
●Presently, many genes from wild varieties are being isolated
with potential cisgenetic application, but restriction due to
laws.
○Except in Canada & Australia.

●European Food Safety Authority has done a safety
assessment.
○Conclusions: same hazards as traditional breeding &
same risks in transfer technology.

(Hou et al., 2014)

10. Cisgenesis VS Traditional breeding
●Cisgenics only contain gene(s) of interest unlike crops that
have been modified by classical breeding, which contain
undesired genetic elements.

●Application of cisgenesis would produce results in only a few
years of experimentation whereas traditional breeding would
take decades to reach a cultivar with desirable traits.
E.g: Breeding of apple for scab resistance took 50 years (Hou
et al., 2014).

11. Intragenesis
●Transfer of genes between crossable species.

●An alternative to transgenics, just like cisgenics.

●However, unlike cisgenes, intragenes are hybrid genes.
○i.e they can have genetic elements from different genes &
loci, thus
○by using different promoter or terminator regions,
expression of genes can be modified.
○Hence, there is the possibility of new gene
recombinations by in vitro rearrangements of functional
genetic elements.


(Holme et al., 2013)

12. Cisgenesis VS Intragenesis
●Both more generally accepted by the public than the other
techniques since
○they do not involve recombination between non-sexually
compatible organisms.
●No foreign sequences present in the final organism.
○e.g selection marker genes & vector-backbone sequences
●However, cisgenesis is more restrictive than intragenesis.

13. Specific alleles/genes present in
the breeders’ gene pool are
introduced, without any change
to the DNA sequence, into new
varieties.
Genes can be designed using
genetic elements from other
plants with the same sexually
compatibility gene pool.
Thus, the coding regions of a
gene can be combined with
promoters and terminators from
different genes (from the same
sexually compatibility gene pool).
IntragenesisCisgenesis
Cisgenesis can accelerate the
breeding of species with long
reproduction cycles since it does
not contain the linkage drag.

14. Differences between Traditional breeding, Intra &
Cisgenesis

Intragenesis Traditional breeding Cisgenesis
Regulatory elements
New compositions of
coding sequences and
promoters are made (7)
The gene has its native
promoter, introns and
terminator.
The gene has its native
promoter, introns and
terminator.
(7)
Genetic elements
Allows construction of
new genetic
combinations, introducing
variability for gene
expression (1)
Involves both desired
and undesired genetic
elements of crossed
plants
Involves exclusively the
gene(s) of interest and
no undesired genetic
elements (1)
Linkage drag Avoided (4) Present (8) Avoided (8)
Time factor
Time saving since it is a
fast and precise tool
(4)
Time- consuming and
requires several
generations of breeding
and selection
(5)
Time saving but takes
much longer time than
intragenesis since
genes/ fragmented
genes may not be
readily accessible (5+8)
Techniques
Molecular Cloning
techniques:
Recombination (5)
Crossing, mutagenesis
and somatic
hybridisation (5)
Molecular techniques
(5)

15. Differences between Traditional-, Intra- & Cis-
genesis
Intragenesis Traditional breeding Cisgenesis
Safety
Deep concern about
safety and impact on
health and environment
(3)
Safe (crops being
consumed since ages)
No environmental risk
and safe as traditional
bred plants (3)
Gene pool Not conserved (3) Preserved (3) Preserved (3)
Genetic make up
Original make up of
plant is not maintained
Maintain original genetic
make-up of plant variety
(3)
Maintain original genetic
make-up of plant variety
(3)
Vigour of recipient plant
New gene modify vigour
of target plant due to
gene influx from its wild
relatives (8)
Change vigour,
generating a change in
the natural vegetation
(8)
No change in vigour
resulting in no harm to
non-target species/
environmental hazards
and potential allergens
(8)

16. Similarities between Trans, Intra &
Cisgenesis & Conventional Breeding
●Integration of the genes requires chromosome breaks and
natural DNA repair mechanisms.

●The process of creating modified plants aims at reducing the
use of pesticides and insecticides which contribute to
environmental problems .

17. Conclusion
According to the EFSA Panel on GMOs,
●similar hazards can be associated with cisgenic and
conventionally bred plants
●novel hazards can be associated with intragenic and
transgenic plants

These breeding techniques can have variable frequencies and
severities of unintended effects.
The effects differ from breeding techniques and can not be
predictable.
Risks to human and animal health will depend on the exposure
frequency; how the plant is cultivated and consumed.

18. References
1)Espinoza, C., Schlechter, R., Herreta, D., Torres E., Serrano, A., Medina, C.
and Arce-Johnson, P. (2013). Cisgenesis and Intragenesis: New tools for
improving crops. Biological Research, 46, pp 323-331.
2)FiBL. (2001). An evaluation for organic plant breeding. Plant Breeding
Techniques.
http://www.seedalliance.org/uploads/pdf/FiBL-PlantBreeding.pdf
[Date accessed: 25.01.15]
3)Holme, I.B., Wendt, T. and Holm, P.B. (2013). Current developments of
intragenic and cisgenic crops. ISB news report, Aarhus University, Faculty of
Science and Technology - Department of Molecular Biology and Genetics
Research Centre Flakkebjerg, DK-4200 Slagelse, Denmark
4)Holme, I.B., Wendt, T. and Holm, P.B. (2013). Intragenesis and cisgenesis
as alternatives to transgenic crop development. Plant Biotechnology Journal, 11,
pp 395-407.
5)Hou, H., Atlihan, N. and Lu, Z-X (2014). New biotechnology enhances the
application of cisgenesis in plant breeding. Frontiers in plant science, 5(389), pp
1-5.

19. References
6)Podevin, N., Devos, Y., Liu, Y., Kärenlampi, S.O., Bradshaw, J., Jones, H.,
Kleter, G., Kuiper, H., Pöting, A., Sweet, J.B., Davies, H.V., et al. (2012).
Scientific opinion addressing the safety assessment of plants developed through
cisgenesis and intragenesis. EFSA Journal, 10(2), pp 1-33.
7)Schouten, H.J. and Jacobsen, E. (2008). Cisgenesis and intragenesis,
sisters in innovative plant breeding. Trends in Plant Science, 13(6), pp 260-261.
8)Telem, R.S., Wani, S.H., Singh, N.B., Nandini, R., Sadhukhan, R.,
Bhattacharya, S. and Mandal, N. (2013). Cisgenics – A sustainable approach for
crop improvement. Current Genomics, 14, pp 468-476.
9)Wiel, C.V.D., Schaart, J., Niks, R., and Visser, R. (2010). Traditional Plant
Breeding methods. Wageningen.
http://www.rexresearch.com/agplntbrdg/tradplntbrdmethd.pdf
[Date accessed: 25.01.15]

20. Thank you for your attention!

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