Could gene editing be the solution to food shortage?

GMO tomato. [Courtesy: iStockphoto]

The ageless debate on genetically modified organisms (GMOs) is getting a new twist as scientists make fresh discoveries.

Experts from the International Institute of Tropical Agriculture (IITA) are now keen to extinguish a lingering assumption that genetic modification, and gene editing, are more or less the same thing, or are closely related.

Leena Tripathi, the Director of East Africa Hub at IITA, insists that genome editing, which is fast gaining popularity, should not be regulated by governments the same way genetic modification (GM) is.

A world that struggles to be food secure, where climate change seems to be on course to exacerbating the food insecurity problem, is grappling for solutions, which is why the debates on genome editing and genetic modification rage.

“Nearly a billion people are going hungry in the world,” says Dr Tripathi. With the world expected to host 10 billion people by 2050, serious efforts are needed to increase food production using limited resources.

As human imagination gets stretched, IITA says that genome editing is yet the surest way to ensure the globe has sufficient food that can cater for a rapidly increasing population.

Alongside this, broad-ranging support is required for agricultural improvements in Africa, says Dr Tripathi, including recognition of farmer needs, introduction of high yielding varieties of crops, making planting material widely available and affordable, and facilitation of access to markets.

Gene editing is a group of technologies that give scientists the ability to make permanent changes at specific sites in the genome of an organism.

“It is mediated by the cell’s own DNA-repair machinery, and lacking in any foreign DNA,” says Dr Tripathi.

“It is used to precisely and efficiently make specific changes to the DNA of a cell or organism. An enzyme cuts the DNA at a specific sequence, and when this is repaired by the cell a change or ‘edit’ is made to the sequence.  Genome editing can be used to add, remove, or alter DNA in the genome.”

DNA- deoxyribonucleic acid- is a molecule that carries genetic instructions (development, functioning, growth and reproduction) in all living things.

“Nature has been editing genome for a very long-time creating variations. In the 20th century, mutations were accelerated through chemicals and radiations. Later technologies were developed for precise gene targeted mutations,” Dr Tripathi says.

CRISPR-clustered regularly interspaced short palindromic repeats-has rapidly become the most popular genome editing approach. 

CRISPR-Cas9, which is CRISPR-associated protein 9, won two scientists the Noble Prize in 2020. It is believed to be faster, cheaper, more accurate, and more efficient than other existing genome editing methods.

By “remembering” the DNA of a virus, an organism can produce RNA- ribonucleic acid- segments from the CRISPR arrays, which are DNA segments created by the organism from capturing snippets of the invading virus’ DNA- to target the viruses' DNA, and, using Cas9, disable the virus.

The problems that genome editing may run into have ready solution, experts say.

IITA says that unwanted genetic changes in plants due to off-target mutations can be avoided by improving RNA guide–design strategies, ribonucleoprotein delivery and integration of inducible CRISPR-Cas. Transgene integration, which could be a biosafety concern, can be mitigated by DNA-free genome editing that involves delivering in vitro pre-assembled CRISPR-Cas9 ribonucleoproteins and by back-crossing to segregate the transgene.

The organization is driving a campaign to have genome-edited crops not regulated as GMOs, insisting that by not introducing foreign genes into an organism, they do not pose a biosafety hazard.

“In 2015, Argentina developed the first regulation in the world for gene-edited products,” says Dr Tripathi.

Nigeria became the first African country to issue gene editing guidelines, and talks in Kenya are in “advanced stages”.

This even as Kenyan experts differ sharply on GMOs, proponents bashing opponents for their lack of commitment to the urgent fight against food insecurity.

Public or academic institutions have been more involved in the research and development of genome editing than private companies. Several countries have made progress in the development and commercialisation of genome-edited crops.

“We now have non-browning mushrooms in US and Canada.  Calyno, a high-oleic soybean oil, is the first gene-edited food product on the US market," says Tripathi.

"Gene-edited, blight-resistant rice, was approved by The United States Department of Agriculture (USDA) and Colombian regulators. Japan approved first gene-edited tomato rich in gammaaminobutyric acid (GABA) to fight high blood pressure."

Argentina has non-browning potatoes, with the genes of the sugars responsible for the browning process turned off.

The country has also managed to develop higher-quality alfalfa through genome editing. 

While GMO inserts foreign genes into an organism, according to IITA, genome editing targets endogenous genes - those that originate from within an organism and very precisely without inserting any foreign gene.

“Gene editing is simpler and faster.  Gene-edited products are not regulated similar to GMO in many countries,” the organization says. IITA hopes that other countries follow suit.

While conventional breeding, in which a favourable trait is incorporated into a crop through methods such as selective mating, is not expensive and is unregulated, it is “not possible if the trait is not present in germplasm pool,” Dr Tripathi says.

Germplasm is living tissue from which new plants can be grown. The only two alternatives are GM and gene editing.

As a way of fighting Banana Xanthomonas Wilt (BXW), a banana bacterial disease that spreads fast, damaging the crop and leading to potential hunger for millions who rely on banana as staple food especially in East African countries, a disease-resistant genome-edited banana can be created through overexpression of defence genes and knockdown of susceptibility genes.

The resultant crop will have no foreign DNA after the gene-editing, which makes the product unlikely to have biosafety issues, IITA says.  

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