Potatoes are genetically modified through a handful of laboratory techniques that either insert foreign DNA into the plant’s genome or edit the potato’s own genes in place. The most established method uses a soil bacterium called Agrobacterium tumefaciens as a natural delivery vehicle to carry new genetic instructions into potato cells. More recently, CRISPR-Cas9 gene editing has emerged as a way to make precise changes without adding any outside DNA at all. The specific method chosen depends on what trait researchers want to achieve, and the story of GM potatoes is more tangled than most people realize.
The Agrobacterium Method
Agrobacterium tumefaciens is a bacterium that, in the wild, infects plants by injecting a small piece of its own DNA into plant cells. Scientists figured out decades ago that they could hijack this natural process: strip out the bacterium’s disease-causing genes, replace them with whatever gene they want the potato to carry, and let the bacterium do the delivery work. The result is a potato cell with a new gene stably integrated into its chromosomes, which can then be grown into a whole plant through tissue culture.
In practice, researchers take small pieces of potato tissue, often nodes or internodal stem segments, and expose them to the engineered Agrobacterium strain. A study using three commercial potato varieties (Diamant, Cardinal, and Granola) demonstrated this approach by infecting tissue segments with Agrobacterium tumefaciens strain LBA4404 carrying marker genes, then regenerating whole plants from the transformed tissue either directly or through an intermediate step involving callus (a mass of undifferentiated cells).1Plant Tissue Culture and Biotechnology. Agrobacterium-mediated Genetic Transformation for Local Cultivars of Potato (Solanum tuberosum L.) Using Marker Genes This Agrobacterium-mediated approach remains the workhorse method for potato transformation worldwide because it is reliable, well understood, and works across many potato varieties.
Alternative Delivery Methods
Agrobacterium is not the only game in town. Two other techniques bypass the bacterium entirely and push DNA directly into potato cells. Particle bombardment, sometimes called the “gene gun,” involves coating microscopic gold or tungsten particles with DNA and literally shooting them into plant tissue at high speed. The other is PEG-mediated transformation, which uses a chemical (polyethylene glycol) to coax naked DNA through the membranes of protoplasts, which are plant cells that have had their rigid cell walls dissolved away.
A comparative study of both methods found that particle bombardment yielded about 1.8 transformation events per shot, while PEG-mediated uptake yielded roughly 67 events per million treated protoplasts.2PubMed. Direct gene transfer in potato: a comparison of particle bombardment of leaf explants and PEG-mediated transformation of protoplasts These numbers sound modest, and they are. Both techniques have lower overall efficiency than Agrobacterium transformation for most applications, but they become valuable when a researcher needs to avoid Agrobacterium-derived DNA sequences in the final plant or when working with varieties that do not respond well to bacterial infection.
CRISPR Gene Editing in Potatoes
CRISPR-Cas9 has reshaped the conversation about potato modification since roughly 2015. Instead of inserting a gene from another organism, CRISPR uses a guided molecular “scissors” approach to cut the potato’s own DNA at a specific location. The cell’s natural repair machinery then stitches the break back together, often introducing a small error that disables the target gene. The result is a potato whose genome has been tweaked, not supplemented with foreign material.
The appeal is obvious, but potatoes present an unusual technical challenge. Most commercial potato varieties are tetraploid, meaning they carry four copies of every gene instead of the two copies found in humans or the single set in many crop plants. To fully knock out a gene’s function, researchers must successfully edit all four copies in the same cell. Early work showed this was achievable but difficult. One study targeting the gene for granule-bound starch synthase (GBSS) found mutations in at least one allele in roughly 2 to 12 percent of regenerated shoots, with multiple alleles mutated in up to two-thirds of confirmed mutant lines, but complete four-allele knockouts occurred in only about 2 percent of regenerated plants.3PubMed Central. Efficient targeted multiallelic mutagenesis in tetraploid potato (Solanum tuberosum) by transient CRISPR-Cas9 expression in protoplasts
Researchers have since improved those odds dramatically. By swapping in promoter sequences native to potato rather than borrowed from the model plant Arabidopsis, one group increased the rate of full allelic editing from about 8 percent to 71 percent in protoplasts of the Desirée cultivar. Among randomly selected regenerated shoots, about 35 percent showed editing across all four alleles.4Scientific Reports. High efficacy full allelic CRISPR/Cas9 gene editing in tetraploid potato Another team developed a system called CRISPR/dMac3-Cas9, which boosted the production of the Cas9 protein using a translational enhancer, and successfully created four-allele knockouts in both GBSS and starch branching enzyme genes.5PubMed Central. Efficiency of potato genome editing: Targeted mutation on the genes involved in starch biosynthesis using the CRISPR/dMac3-Cas9 system The tetraploid hurdle has not been eliminated, but it is no longer the bottleneck it once was.
RNA Interference and Gene Silencing
Before CRISPR arrived, researchers had another powerful tool for altering potato traits without importing foreign genes from distantly related organisms: RNA interference, or RNAi. This technique uses small RNA molecules to intercept and degrade the messenger RNA produced by a particular gene, effectively silencing it. The gene is still present in the potato’s DNA, but it can no longer produce its protein.
RNAi became the backbone of the Innate potato line developed by Simplot (a major supplier to the French fry industry). Innate potatoes use silencing constructs built entirely from potato DNA sequences, which is why the company markets them as “intragenic” rather than transgenic. The practical payoff is a potato that produces fewer reducing sugars during cold storage and lower levels of the amino acid asparagine, both of which are precursors to acrylamide, a potentially harmful compound that forms when potatoes are fried at high temperatures.
Solving the Acrylamide Problem
When potatoes are stored at cold temperatures (standard practice to extend shelf life), an enzyme called vacuolar invertase breaks down sucrose into glucose and fructose. These reducing sugars react with amino acids during frying in what is known as the Maillard reaction, producing both the brown color of chips and fries and, unfortunately, acrylamide. This is why chips made from cold-stored potatoes often come out unpleasantly dark and carry higher acrylamide levels.
Silencing the vacuolar invertase gene (VInv) in potato has proven remarkably effective. Researchers working with four chip-processing cultivars found that RNAi lines with more than 90 percent reduction in VInv gene activity accumulated roughly 93 percent fewer reducing sugars during cold storage. Chips from these lines were light in color and significantly lower in acrylamide, with no apparent effect on growth or tuber yield.6Crop Science. Developing Cold‐Chipping Potato Varieties by Silencing the Vacuolar Invertase Gene A separate study showed chips from VInv-silenced Russet Burbank tubers stored at 4°C had about a fifteen-fold reduction in acrylamide compared to controls.7PubMed Central. Suppression of the vacuolar invertase gene prevents cold-induced sweetening in potato
Some researchers took the strategy further, silencing not just VInv but also asparagine synthetase genes (StAS1 and StAS2) in a triple-silencing approach. The best triple-silenced lines produced fried products with only one-fifteenth of the acrylamide content of controls. Interestingly, that level of reduction was similar to what the best VInv-only silenced lines achieved, suggesting that tackling reducing sugars alone is sufficient for most practical acrylamide reduction.8PubMed Central. Silencing of vacuolar invertase and asparagine synthetase genes and its impact on acrylamide formation of fried potato products Field trials confirmed that silencing asparagine synthetase alone did not affect tuber yield or quality either.9Plant Biotechnology Journal. Tuber-specific silencing of asparagine synthetase-1 reduces the acrylamide-forming potential of potatoes grown in the field without affecting tuber shape and yield
Reducing Browning and Bruising
Anyone who has sliced a potato and watched it turn grey-brown within minutes has witnessed enzymatic browning. The culprits are polyphenol oxidase (PPO) enzymes, which react with oxygen when cells are damaged. Browning is not just cosmetic; it leads to significant food waste, as consumers and processors reject discolored tubers.
CRISPR-Cas9 has been used to knock out specific PPO genes in potato. Researchers editing the StPPO2 gene in the Desirée cultivar achieved mutations across all four alleles, which reduced PPO enzyme activity in tubers by up to 69 percent and cut enzymatic browning by 73 percent compared to unmodified controls.10PubMed Central. Reduced Enzymatic Browning in Potato Tubers by Specific Editing of a Polyphenol Oxidase Gene via Ribonucleoprotein Complexes Delivery of the CRISPR/Cas9 System Follow-up work in additional cultivars confirmed that editing tuber-specific PPO genes substantially lowers both enzymatic activity and visible browning.11PubMed. CRISPR/Cas-mediated polyphenol oxidase gene knockout in potato reveals divergent roles in resistance to bacterial wilt and late blight One nuance the latter study revealed, however, is that PPO enzymes also play a role in disease resistance. Knocking them out reduced browning but had complex effects on the plant’s ability to fight bacterial wilt and late blight, illustrating why editing one trait can have unexpected ripple effects.
The Rise and Fall of the First GM Potatoes
The very first genetically engineered potatoes to reach farmers’ fields were Monsanto’s NewLeaf line, approved for U.S. commercialization in 1995. These carried a gene from the bacterium Bacillus thuringiensis (Bt), which produced a protein toxic to Colorado potato beetle larvae. Three Russet Burbank, Superior, and Atlantic varieties were transformed with the Bt gene, and the resulting potatoes not only killed beetles that fed on them but also shrank the ovaries of surviving female beetles, reducing their ability to reproduce. By 1998, NewLeaf potatoes were planted on roughly 55,000 hectares. Monsanto also released NewLeaf Plus potatoes with added resistance to potato leafroll virus.12PubMed Central. Potato improvement through genetic engineering
Then, by 2001, commercialization collapsed. The technical performance of the potatoes was never the problem; consumer resistance was. Major food companies, particularly McDonald’s and Frito-Lay, refused to buy GM potatoes, and growers found the crop unprofitable. The episode illustrates a pattern that has repeated across GM potato development: the science often works, but market acceptance does not always follow. It took more than a decade before a second generation of GM potatoes, Simplot’s Innate line, reached the market, this time engineered with potato-derived sequences and framed around consumer benefits like lower acrylamide rather than agronomic traits like pest resistance.
Modifying Starch Composition
Potato starch is a massive industrial commodity, used in food processing, paper manufacturing, adhesives, and biodegradable packaging. Natural potato starch is a mix of two molecules: amylose (a straight-chain starch) and amylopectin (a branched-chain starch). Many industrial applications work better with pure or nearly pure amylopectin, which has superior binding and gelling properties.
Researchers have used both RNAi and CRISPR to knock out granule-bound starch synthase (GBSS), the enzyme responsible for making amylose. Successful four-allele knockouts of GBSS produce potatoes whose starch is essentially 100 percent amylopectin, sometimes called “waxy” starch. As described above, early CRISPR work achieved this in a small percentage of regenerated plants, while newer systems have pushed the success rate much higher. Editing starch branching enzyme genes offers the opposite effect, potentially increasing amylose content for applications where a firmer gel is desirable. Because starch modification has obvious commercial value, this is one area where gene-edited potatoes could move toward commercialization relatively quickly, especially in countries where gene-edited crops without foreign DNA are regulated more lightly than traditional GMOs.
Safety and Compositional Studies
Whenever a potato line is genetically modified, regulators want to know whether its nutritional makeup and safety profile have changed in unintended ways. A 90-day feeding study tested a GM potato line engineered to have an altered ratio of two naturally occurring glycoalkaloids (alpha-solanine and alpha-chaconine, compounds potatoes produce as natural pesticides). Hamsters fed the GM line showed only a small number of statistically significant differences from animals fed the unmodified parent variety, and none of those differences raised safety concerns for human or animal consumption. Compositional analysis also found the GM tubers to be broadly similar to their wild-type counterparts in terms of nutritional value.13PubMed. Compositional and toxicological analysis of a GM potato line with reduced α-solanine content–a 90-day feeding study in the Syrian Golden hamster
This kind of study is representative of the general approach: compare the modified potato to its unmodified parent across a broad panel of nutrients, toxins, and allergens, then look for unexpected shifts. The presence of a minor difference is not automatically a red flag, because conventionally bred potatoes also vary in composition from one variety to the next. What regulators look for is whether any difference falls outside the normal range seen in commercial potato varieties.
Transgene Silencing Over Time
One underappreciated challenge with genetic modification in potato is that inserted genes can gradually shut down over successive growing seasons. Because potatoes are propagated vegetatively (you plant a piece of tuber, not a seed), a single clone can be maintained for many years. A five-year study tracked reporter genes inserted into potato plants propagated vegetatively through multiple generations. Roughly a quarter of the transgenic lines experienced complete silencing of their inserted genes over the study period. The silencing was more likely in lines that started with higher expression levels and more copies of the inserted DNA. Treatment with a demethylation drug partially reversed the silencing of one gene, indicating that at least some of the shut-down was driven by epigenetic changes, essentially the plant’s genome tagging the foreign DNA as something to ignore.14PubMed Central. Successive silencing of tandem reporter genes in potato (Solanum tuberosum) over 5 years of vegetative propagation
For developers of GM potato varieties, this means long-term stability testing is essential. A trait that performs beautifully in the greenhouse during year one could fade over the vegetative generations that a commercial variety would undergo in real-world agriculture. CRISPR-edited potatoes may sidestep this issue, since they involve changes to the native genome rather than the addition of foreign sequences that the plant’s epigenetic machinery might recognize and silence.
Gene Flow and Environmental Concerns
One concern with any GM crop is whether modified genes could escape into wild relatives through cross-pollination. Potato is somewhat unusual among major crops in this regard. Commercial potatoes are propagated clonally, not by seed, which limits natural gene flow. Potatoes do flower and can produce true seed through pollination, but most modern varieties have reduced fertility, and cross-pollination with wild species requires closely related wild relatives to be growing nearby. A scoping review of gene flow risks in GM crops noted that gene flow in potato is less studied than in other major crops, with concerns centered primarily on contamination risks in the Andean region of South America, where wild potato relatives are diverse and abundant.15PubMed Central. Gene Flow and Hybridization Potential Between GM/NGT Crops and Conventional Varieties or Wild Relatives: A Scoping Literature Review with Emphasis on Oilseed Rape (Brassica napus L.) and Potato (Solanum tuberosum L.) In North America and Europe, where most commercial GM potato production would occur, the risk of gene flow to wild relatives is considered low.
Regulatory Differences Between GM and Gene-Edited Potatoes
How a potato is modified determines how it is regulated, and the distinction matters enormously for whether a modified variety will ever reach your plate. Traditional GM potatoes that carry DNA from another species (transgenic) go through a rigorous, multi-year regulatory process in most countries. In the United States, three agencies (USDA, EPA, and FDA) may all be involved. In the European Union, approval has been effectively blocked for decades by political opposition.
Gene-edited potatoes that contain no foreign DNA have begun to fall into a different regulatory category in some jurisdictions. The United States, Argentina, Brazil, Japan, and several other countries have adopted frameworks that exempt certain gene-edited crops from the full GM regulatory pathway, provided no transgenic material remains in the final plant. This is one reason why CRISPR editing is generating so much excitement among potato researchers. A CRISPR-edited potato with reduced browning or altered starch could, in principle, reach the market faster and at lower cost than a traditional GM potato carrying the same trait engineered by transgene insertion.16PubMed Central. CRISPR-Cas Gene Editing Technology in Potato The EU is still debating its approach, and any regulatory change there will have global ripple effects given Europe’s influence on international food trade standards.
Diploid Potato Breeding and Hybrid Seeds
A parallel revolution in potato science may change how genetic modification fits into the broader picture of potato improvement. Conventional potatoes are tetraploid, which makes traditional crossbreeding slow and unpredictable because of the complex genetics involved. A growing number of research groups are working to develop diploid potato varieties, which carry just two copies of each gene and behave much more like standard crop species in a breeding program.
Diploid potatoes have historically been self-incompatible (they cannot pollinate themselves), which made creating inbred lines impossible. Gene editing has been used to knock out the self-incompatibility gene, opening the door to true inbred lines and hybrid seed production for potato for the first time. This is a big deal because it would allow potato breeders to use the same rapid improvement cycle that has driven gains in crops like corn and tomato.17PubMed Central. New Frontiers in Potato Breeding: Tinkering with Reproductive Genes and Apomixis If diploid hybrid potatoes become commercially viable, gene editing could be layered onto a breeding pipeline that moves far more quickly than anything possible with today’s clonally propagated tetraploid varieties. The two technologies complement each other: diploid breeding simplifies the genetics, and CRISPR makes targeted improvements faster. Several startups and public breeding programs are already pursuing this combined approach.
Potatoes as Pharmaceutical Factories
One of the more unusual applications of potato genetic modification has nothing to do with food. Researchers have explored using genetically modified potato plants as production platforms for pharmaceutical proteins, including vaccine antigens. The idea is to engineer potatoes to produce a protein from a pathogen (such as the hepatitis B surface antigen), then use the harvested tubers as an inexpensive, shelf-stable delivery vehicle for the antigen. Plants including potato have been utilized to produce antigens targeting diseases such as cholera, hepatitis, measles, and diarrheal illness.18Current Research in Biotechnology. Insights into the world of edible vaccines: From lab to reality
Edible vaccines have been a concept since the 1990s, and potatoes were among the first plants tested because they are easy to transform and widely grown. In practice, the approach has remained largely experimental. Dose control is a persistent problem: the amount of antigen in each tuber varies depending on growing conditions, storage, and the specific transformation event. Cooking also denatures many proteins, which complicates the use of potato specifically since it is almost always eaten cooked. Other plant platforms have overtaken potato for most pharmaceutical protein work, but the concept highlights how versatile genetic modification techniques can be once established in a crop species.