Friday, December 1, 2023

Gene edits save time

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Plant pathologists at Minnesota University are on the front lines of developing new techniques for early detection of plant diseases. Samantha Tennent visited the university and heard first-hand about their work.
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Nine million people die annually from starvation and malnutrition and it is estimated the annual mortality rate will reach 12.5m people by 2050.

Growing productive, profitable food while using less chemicals motivates scientists as much farmers and consumers. 

Professor Jim Bradeen and his colleagues at Minnesota University are researching gene editing and how it might help feed the world sustainably.

Gene editing is a group of technologies that lets scientists change an organism’s DNA. The technologies allow genetic material to be added, removed or altered.

Gene editing is different from genetic modification because no foreign DNA is inserted into a gene-edited organism.

Disease resistance is present in the genetic make-up of all plants. Scientists have developed a technology known as the resistance gene enrichment and sequencing method (RenSeq). RenSeq enables sequencing of the portion of plant genomes that contain the disease-resistant genes.

This technology has sped up the cloning process.

“In six months we’ve been able to map and clone four disease resistant genes from wheat,” Bradeen said.

“With traditional methodology we estimate it would take about a decade for each of those genes to be mapped and cloned.”

Gene banks are scattered all over the world. They preserve thousands of genetic samples from organisms and plants and store them in frozen vaults. By mining gene banks scientists can leverage the evolutionary history of resistant genes.

The rate of discovery has sped up as more plant genomes are sequenced.

“We know what a disease-resistant gene looks like.

“Through computer algorithms we can survey a DNA sequence and identify particular regions that have hallmarks that tell us how this gene allows the plant to interact with microbes, to detect a pathogen or respond to a pathogen.

“The challenge is to understand what pathogens the plants interact with.”

Scientists are pursuing research to let them set the strength of the disease resistance gene.

If genes are turned up it will induce greater resistance. Whether a gene is turned on or off is regulated by a DNA sequence known as a promoter.

“If we modify that promoter region using gene editing we have the potential to turn genes up and potentially enhance disease resistance.”

It has been successful in studies of late blight disease in potatoes. Bradeen has built his career around late blight research.

There are several technologies available to researchers involved in gene editing. One technique, known as Crispr (clustered regularly interspaced short palindromic repeats) allows scientists to make precision edits to any DNA.

Crispr presents a lot of potential for use with gene editing but there are challenges too.

“While we can modify many regions of plant genomes there are still technical constraints that limit where we can modify and there seems to be a lot of variance in their tolerance for sequence mismatch.

“Something else we need to understand are the off-target effects from gene editing, which is when genes somewhere else in the plant genome are impacted.”

Bradeen says they need to work through the challenges to gain better understanding before gene editing can be used on a large scale.

There is also a question mark around regulation of gene edited crops.  

Europe classes them as GMO while the United States doesn’t regulate them if the edited crop is indistinguishable from the unedited crop.  

The regulatory landscape needs to be fully navigated but gene editing is one technology offering promise of feeding the world sustainably.

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