Gene editing safety sparks clash at international symposium, traditional breeders remain cautious

This year's Nobel Prize in Chemistry was awarded to two women scientists from the US and France researching "Gene Editing" technology, but this technology has many controversies in medicine, and scholars from various countries also hold differing views on its agricultural application. Last week (October 13), the International Symposium on Crop Precision Breeding was held at Chung Hsing University, where scholars from various countries clashed over the pros and cons.

Some attending scholars believe that gene editing technology (SDN1), which disrupts certain gene segments and lets the genes repair themselves to produce mutations, does not insert foreign genes, is no different from traditional breeding, and can even increase the efficiency of traditional breeding, and therefore should not be regarded as genetic modification.

Scholars who do not endorse gene editing believe that gene editing can have "off-target effects," meaning that non-target gene segments may also be altered, potentially producing unforeseen side effects. At the symposium, a British scholar pointed out that chromosomal chaos and protein mutations have appeared in many experiments and papers, and that gene interference may produce toxins and allergens, and that gene editing cannot currently be proven safe.

Chou Kuo-lung, known as "Mr. Edamame" and director of the Chinan Branch Station of the Kaohsiung District Agricultural Research and Extension Station, believes that from the literature, gene editing technology that does not insert foreign genes can indeed shorten breeding time. "The technology itself is neutral; whether it is controversial depends on the original intention of the user. Is it to 'Feeding the world'? Or is there another agenda?"

Gene editing has no foreign genes, breaks gene segments so they repair themselves

Since "the father of genetics" Mendel, scientists have improved crops through crossbreeding. After DNA sequencing emerged in the 1960s, modern breeding technology flourished, with genetic modification and gene editing technologies in particular arousing much controversy.

Hung Chuan-yang, professor in the Department of Agricultural Chemistry at National Taiwan University, explained that breeding involves repeated crossbreeding of crops, during which genetic variation occurs, allowing selection of traits that meet people's needs, such as different colors, fruit weights and plant heights. However, because naturally induced genetic variation requires large numbers of crossbreeding samples and occurs at low probability, traditional breeding currently uses three methods: physical (Gamma-ray), chemical (EMS agent) or biological mutagenesis.

Regarding the difference between gene editing and genetic modification technologies, Hung Chuan-yang explained that genetic modification is commonly known as "transgenics," and its principle is to break a gene and then insert a desired foreign gene (Note 1); gene editing, on the other hand, breaks part of a crop's gene segment, and the crop repairs itself, producing mutations during repair, but it is still the gene of the same species of organism and can continue to reproduce offspring.

Hung Chuan-yang said the drawback of traditional breeding is that it is not precise enough; for example, rice bred for disease resistance may become unpalatable. In addition, traditional breeding requires repeated backcrossing (Note 2), and some crops have long growth periods, making breeding time-consuming. The emergence of gene editing is precisely to make breeding technology more precise and more efficient.

Is gene editing technology precise? Whether "off-target effects" can be overcome remains disputed in academia

Scholars and civil society groups that do not endorse gene editing and genetic modification believe that the food safety risks of crops produced by these technologies have not been assessed, and that these technologies have "off-target effects," meaning non-target gene segments may also be altered, potentially producing unforeseen side effects.

For example, the US company Recombinetics in 2016 used gene editing technology to breed hornless cattle. Although there were no foreign genes, US authorities found that the hornless cattle carried three antibiotic-resistance genes from bacteria.

Regarding doubts about off-target effects, Hung Chuan-yang said that gene editing produces different results in animals and plants. If gene deletion occurs in animals, it may mean one fewer eye or one fewer leg, but in plant breeding, large numbers of variations are inherently needed for selection, and if off-target effects produce non-target traits, they can simply be eliminated.

However, Michael Antoniou, professor in the Department of Molecular Genetics at King's College London in the UK, questioned: "If it is really as safe as natural mutations, then why apply for patents?" Many supporters of gene editing believe that off-target effects are not very harmful as long as they are precisely controlled, but in fact, large-scale genetic changes can affect the functions of other genes, and chromosomal chaos and protein mutations have appeared in many experiments and papers.

Michael Antoniou believes that the chemical interactions within biological genes are extremely complex. Taking "hornless cattle" as an example, gene interference may also produce toxins and allergens, and gene editing cannot currently be proven safe.

Countries define gene editing differently; the EU regards it as genetic modification, while the US, Japan and Australia regard it as non-genetic modification

Crops bred using gene editing technology are mainly rice, tomatoes, corn, wheat, soybeans, cotton and citrus crops, but for the public, is eating gene-edited crops safe?

At present, authorities in the US, Japan and Australia have all regarded gene-edited crops and products as non-genetically modified, but the EU still considers gene editing to be genetic modification. The symposium invited scholars from the US, Australia, Japan and Europe to explain the current situation in each country online.

Yutaka Tabei, director of the Extension Office at the National Agriculture and Food Research Organization in Japan, said,