2. Blog: Cisgenic plants for Switzerland

Cisgenic plants for Switzerland

Questions for the second blog entry:

1. Explain one method for producing a cisgenic plant.

2. How is this process similar and how is it different from producing a transgenic plant?

3. How is the result of the cisgenic breeding process different from a classically bred plant? How is it similar?

4. What are the safety concerns of cisgenic plants? Are they different in transgenic plants? Are they different from classically bred plants?

5. In your opinion, is it correct to treat cisgenic plants like transgenic plants?

1. There are several different methods to produce cisgenic plants. One of them and the most commonly used is the Agrobacterium mediated transformation. In this process bioengineers use Agrobacterium tumefaciens, a pathogenic soil bacteria, to insert selected DNA into plant cells. The bacterium causes crown gall disease with the ability of introducing parts of its plasmid DNA through the cell wall. Therefor it is possible to isolate genes of an organism, integrate them into Ti- plasmids between a promoter and a terminator and insert these plasmids into Agrobacteria. Then the bacteria have to be attached to plant cells and the TI- plasmids will enter the selected genes through the cell wall and into the genome of the plant. [1]

Figure 1: The agrobacterium mediated transformation process in a few simplified steps. (Source: slideshare.net)

2. If you just look at the procedure, the processes to produce cisgenic or transgenic plants are the same. Also agrobacterium mediated transformation can be used to produce either cisgenic or transgenic plants. The difference are the isolated genes, which are integrated into the Ti- plasmids and finally into the host plant. If the introduced genes are from a plant species which is naturally crossable with the host, the generated product is called a cisgenic plant. For a transgenic plant, genes of any possible organism can be used to modify the host plant genome. [1]

3. The result of a cisgenic breeding process is a new modified genome with genes of the parental plant and one or more selected new genes from other naturally crossable plants. It would not be possible to identify if the new genome is genetically modified or not.

Transgenic plants on the other hand have genomes with genes from other normally non-crossable species and it is possible to detect the foreign gene(s) and declare it as a transgenic plant. The only similarity in the result is the man-made modification of the genome in a desired positive way. [1]

4. The major concerns about transgenic plants in our society is based on the fact, that there is a mixing of genetic materials of species that cannot hybridize in a natural way. It is therefore a man-made process which is sometimes linked with different fears. For example the possibility of potential health risks for the consumer, a negative impact to the ecosystem by spreading synthetic gene combinations or in general the belief of a disrespect for natural processes in nature. [2]

Cisgenic plants are also man-made, but the gene combinations could also possibly happen in classically bred plants. Concerns in the society about health risks or negative impacts to the ecosystem are less widespread. The belief of a synthetic intervention in nature stays.

Classical bred plants became normal for thousands of years. Concerns about negative impacts are nearly non-existent.

5. In my opinion, it is not correct to threat cisgenic like transgenic plants. Even if the processes to produce these genetically modified plants are similar, the results are different. Transgenic plants have genomes, which would never appear in nature without the man-made modifications. The genomes of cisgenic plants could also occur in a natural way.

But for me, every product should be labelled and it should be clear for the consumer if the product has trans- or cisgenic ingredients. Furthermore the cultivation of every new cis- and transgenic plant should be regulated and should be under quarantine till it is totally clear that there are no negative impacts to the environment or to the consumer. (Also long-term consequences!) (Moratorium for the commercial cultivation of genetically modified plants) [3]

References:

[1]       Narusaka Y., Narusaka M., Yamasaki S. & Iwabuchi M. (2012). Methods to Transfer Foreign Genes to Plants. Transgenic Plants - Advances and Limitations, pp. 173-188, ISBN 978-953-51-0181-9

[2]       Holme I. B., Wendt T. & Bach Holm P. (2013). Intragenesis and cisgenesis as   alternatives to transgenic crop development. Plant Biotechnology Jurnal. Department of Molecular Biology and Genetics, Faculty of Science and Technology, Aarhus University, Research Centre Flakkebjerg, Slagelse, Denmark. pp 397-407

[3]       Bundesgesetz über die Gentechnik im Ausserhumanbereich (Gentechnikgesetz GTG), 814.91, stand 1. Juni 2014