Cisgenics- Transgenics without the Transgene

posted in: Science | 12

Recently at the International Horticultural Congress in Lisbon, Portugal, a workshop was dedicated to transgenic crop biology and its integration with public perception.  As mentioned in previous posts, the central theme is to placate the misinformed public opinion by using clever technologies to circumvent traditional unfounded criticisms of biotechnology.

Dr. Franz Krenz was the first speaker of the session.  His focus was in describing what have been known as cisgenic technologies, or the moniker sometimes applied to allele-specific marker assisted selection, precision breeding.*  Dr. Krenz and colleagues have adopted a very strict interpretation of what cisgenic means.  By his definition, a cisgenic plant contains regulatory regions and protein-coding regions from the same species, shuttled by biotechnological means.  There are no bacterial genes for resistance, no viral promoters, no other genic sequences. Corn to corn, rice to rice, quince to quince.  It would be like moving a gene that controls eye color from one person to another to another to make their blue eyes brown.  Homo sapiens to Homo sapiens.  Nothing fancy.

In plants naturally-occurring beneficial gene variants are quite common, yet oftentimes occur in unimproved species with limited commercial potential.  Specific gene variants confer resistance to disease, variation in flowering time and production traits like fruit size and yield.  These have been described in many horticultural and agronomic crops.  To breed these traits into existing lines using traditional crossing methods might take decades, depending on the crop.  For example, apple scab prevention requires 20-30 sprays per season, sprays that weigh on the environment, the farmer’s bottom line, and place more chemicals into consumer products.  For a long time science has searched for a solution. In 1946 scientists identified natural resistance to scab in Malus floribunda, a wild apple relative.  The gene was identified years later.

Back in the 50’s, crosses were made, and the resistance to scab moved to new commercial lines- along with >30,000 other genes that were potentially inconsistent with commercial apple qualities.  This phenomenon of linkage drag means that you can’t easily just breed in a single desired trait, that you bring the rest of the non-commercial qualities along for the meiotic ride into subsequent generations.  To get the apple-scab resistance gene into plant lines with commercial apple potential took almost fifty years!

Imagine if that single beneficial gene could be picked up and moved to a new line without all the deleterious genetic baggage?  Certainly modern transgenic technologies could do (and did) just that.  Yet to survive the non-scientific onslaught of anti-transgenic interests, scientists had to work around the traditional means of transgenic technologies to make it acceptable.  Over the last decade, scientists have isolated that one beneficial gene, and only that gene, and moved it alone to commercial plants.

The process took a few years rather than five decades and the cost to achieve this and deregulate was about €6M instead of ten times that and many scientist careers.   Dutch consumers do find this form of genetic engineering acceptable, as it provides a healthy product with less chemical intervention and lower environmental impact.  Plus, it is apple genes into apples.  We do that already with crosses.

Still there are opponents to the technology, but most of their their weak arguments disabled via these techniques.  Unfortunately, the end product is the same, maybe even less effective, than if traditional transgenic approaches were used, and it takes a lot more time and money to make it happen.

This is just one example of how scientists are cleverly working around warped public perception problems to solve real issues, and enhance sustainable production.  Cisgenics will be at least a stop-gap solution in the European Union until public education and perception refocus real problems in sustainable agriculture.  For now, the practices of cisgenics may be the central means of introducing traits to plants that can benefit the consumer and environment without the lengthy breeding process, and most of all without raising the ire of those that seek to stop transgenic technology.

*Precision Breeding has also been used to refer to marker assisted selection (MAS), which is a tool for checking the results of breeding experiments, not a type of genetic engineering.

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Kevin is a plant scientist. Kevin stepped down from the board of directors of Biology Fortified in 2018, and no longer contributes to the Biofortified Blog. This article remains published for archival purposes.