Researchers “silence sugars” in genetically engineered potato to cut browning and extend shelf life

06 Jun 2024 --- Scientists in the US have formulated a genetically engineered potato variety to minimize the off-color browning and caramelization in the crop. This yields healthier, higher-quality potato chips with extended cold storage times with potential to address the snack industry’s storage issues. 

The innovation is based on Kalkaska potatoes, a Streptomyces scabies-resistant variety developed by the Michigan State University (MSU), which conducted the study.

Researchers suppressed a gene responsible for producing the vacuolar acid invertase enzyme in the potato, which converts sucrose into reducing sugars like glucose and fructose. “Silencing” the gene that produces it avoids rots and moisture loss.

The research findings are very significant for the US snacks market and producers of chips and French fries. Michigan is the nation’s leading producer of potatoes for chips and the potato industry is valued at US$240 million annually, states the MSU.

The new variety — Kal91.3 potato — can also reduce the environmental impact of the growing process by reducing the amount of fertilizers and pesticides needed to maintain the potato during storage.

Dave Douches, professor in the Department of Plant, Soil and Microbial Sciences and director of the MSU Potato Breeding and Genetics Program, has developed the enhanced potato to “correct the sugar imbalance” in some of Michigan’s commercial chipping potatoes.

“We have chipping potatoes that work well and do their job, but I wanted to take this gene and find out whether it could improve a potato that was having a problem with its sugars.”

“Breeding potatoes is quite challenging because we need so many important traits to line up, but in this case, we just needed one trait to correct the problem. Using this biotech strategy, we succeeded in making a potato that was giving us problems into one that’s now commercially valuable,” notes Douches.

Comparison of Kalkaska and Kal91.03 chipped directly from 3 months storage at 40°F (Image credit: MSU).The findings are published in The Plant Cell.

Withstanding cold storage
Many farmers have traditionally stored chipping potatoes at or around 50°F (10°C) to avoid vacuolar acid invertase from responding to cooler temperatures. However, this makes potatoes more susceptible to damage during storage.

The Kal91.3 potato can help manufacturers overcome this challenge by enabling storage at temperatures as low as 40°F (4.4°C) while maintaining its sugar balance.

“There’s a double value to it,” Douches explains. “The first is that we stabilize the sugars. The invertase silencing slows down the conversion of sucrose into fructose and glucose, so it stabilizes the potato’s sugar while in storage. It’s settling the potato down from a metabolism point of view.”

“The second is that we benefit from storing the potato for longer periods at cooler temperatures.”

Regulatory stance
The US Department of Agriculture’s Animal and Plant Health Inspection Service (USDA APHIS) has granted an exemption to the Kal91.3 potato variety from the biotechnology regulations placed on genetically modified products.

This is based on the organization’s conclusion that the potato does not pose an “increased plant pest risk” related to its conventionally bred counterpart.

Cold storage of potatoes is a key concern for manufacturers who fear damage due to moisture loss.The MSU highlights that the novel potato is “not the first genetically engineered potato with invertase silencing” to be exempt from regulation by USDA APHIS. 

“However, it’s the first genetically engineered vegetable developed by a land-grant university to be exempt from regulation, according to the USDA APHIS website.”

Stabilizing potato supplies 
The MSU states that Michigan is the eighth largest producer of potatoes in the US, and 70% of them are used for chips.

According to Kelly Turner, executive director of the Michigan Potato Industry Commission, the Kal91.3 potato’s storage capacity has the potential to “further stabilize Michigan’s potato industry” by providing a steady supply of potatoes throughout the year, even in the absence of fresh harvests.

 “Not only does the Kal91.3 potato have a high nutrient content, but it also could be grown by using less fertilizers and pesticides, thus reducing the environmental risk and footprint of the potato-growing process,” she observes.

She further notes that potatoes like Kal91.3 also present opportunities to address climate and weather pattern changes, adding that such innovations can help potatoes be “more tolerant during periods of drought.”

“This helps to stabilize yields and ensure food security while maintaining environmental diligence under changing climatic conditions.”

Research-industry collaborations
Collaborative research projects between MSU and the potato industry focus on solving practical problems, such as enhancing disease resistance, combating pests and improving crop yields through genetic modifications, highlights Turner.

The new potato variety can help potatoes be more tolerant to drought and climate change impacts.“These joint initiatives ensure that research efforts are aligned with the industry’s needs, leading to solutions directly applicable to real-world challenges faced by potato growers and processors.”

Douches and his team are now working with Michigan potato industry leaders to evaluate the potential impact of the Kal91.3 potato on the state’s industry, specifically with chipping.

Protecting the potato 
The impact of climate change on crops is driving F&B innovators to develop ways to protect crops and reduce wastage.

 Earlier this year, the USDA investigated the lifecycle of potatoes to help the potato industry maintain the post-harvest quality and prevent post-harvest crop losses, majorly caused by physiological and disease-related processes (10-15%).

Canadian researchers used genomics to create a “super pangenome” that compiled the data from genome sequences of 296 varieties of potatoes and wild versions of 60 species to improve potato germplasm for climate resilience and safeguarding food security.

Mapping out crops’ genomes is a helpful tool for speeding up plant breeding programs and developing varieties with higher quality or resistance to diseases or climate change.

Meanwhile, AI and drone technology can also help prevent potato damage from weeds, diseases like Potato Virus Y and early detections of early and late blight, agriculture technology start-up Croptic told Food Ingredients First last year.

By Insha Naureen