Project GREEEN backs research into new way of breeding potatoes

Roughly ten years ago, Dave Douches, a professor in Michigan State University’s Department of Plant, Soil and Microbial Sciences and director of MSU’s Potato Breeding and Genetics Program, led the Solanaceae Coordinated Agricultural Project (SolCAP). The project, funded by the U.S. Department of Agriculture’s National Institute of Food and Agriculture (USDA NIFA) to advance potato and tomato crops, gave rise to a new potato-breeding venture Douches has been exploring ever since.

Dave Douches, professor in Michigan State University’s Department of Plant, Soil and Microbial Sciences and director of MSU’s Potato Breeding and Genetics Program.

Most potatoes grown in the world are tetraploids, meaning they have four sets of chromosomes. This makes breeding potatoes relatively difficult due to the high level of genes that must be crossed.

During his time as director of SolCAP, Douches recognized the need for finding the genetic material needed to cultivate a diploid potato, one that has just two sets of chromosomes. Both tetraploid and diploid potatoes originated from South America centuries ago, but it ultimately was the tetraploid potato that reached the global market and is what consumers typically buy today.

″It was in that project I realized we needed to think of a new way of breeding the potato at the diploid level and to capture the advantage and simplicity of using diploid genetics,″ Douches said.

Diploid breeding allows for genetic advances to happen quickly. At the diploid level, scientists can edit genes with a greater probability of achieving desired traits than they can at the tetraploid level.

To help launch this research, Douches applied for and received Project GREEEN funding in 2018.

Project GREEEN, Michigan’s plant agriculture initiative that’s housed at MSU and includes plant-based commodity groups and businesses, MSU AgBioResearch, MSU Extension and the Michigan Department of Agriculture and Rural Development, has been critical in pursuing a diploid potato germplasm — the genetic material of reproductive cells used for breeding, conservation and research.

″Since 2018, Project GREEEN has helped us jumpstart this work,″ Douches said. ″It’s really been crucial work because we’ve been taking advantage of modern technology and gene editing to impart self-compatibility in diploid potatoes.″

Self-compatibility refers to the process of a plant being able to pollinate itself from its own seeds and fruits. Before the research funded by Project GREEEN, self-compatibility was a rare trait within diploid potatoes. Now, it’s a viable option that may open the door for numerous varieties of diploid potatoes to easily and quickly be developed.

Douches said he and his team are preparing to submit a petition to the USDA that, if granted, would allow the gene-edited potato capable of self-compatibility to become exempt from regulations with minimal restrictions, a similar standard that conventional foods are held to.

Another challenge Project GREEEN has helped Douches overcome in breeding potatoes is developing further resistance to pests, specifically the Colorado potato beetle. Prior to studying potatoes at the diploid level, Douches said there was little progress made in finding the gene that would protect potatoes against the beetle. However, with Project GREEEN funding, he was able to hire a graduate student who discovered the gene.

″This is a perfect example of not being able to make any progress for insect resistance at the polyploid (having more than two homologous sets of chromosomes) level,″ Douches said. ″It’s just not the way to approach it — the genetics is too complex. The genes get diluted in the polyploid crops.

″At the diploid level, we’ve been able to tackle this. I received Project GREEEN funding and brought on a great graduate student, Natalie Kaiser, who took this work on. She identified the resistance gene in a germplasm that was hovering around for 30 years, but because all the previous research done on it was at the polyploid level, no one could make any progress on it.

″Now we’re integrating the gene into our diploid germplasm through a simpler breeding system.″

One perk of breeding potatoes with the resistance gene is that in doing so, fewer pesticides need to be applied during the growing season. This can save growers money, said Kelly Turner, the executive director for the Michigan Potato Industry Commission.

″When you’re looking at the viability of the industry, you have to make sure growers are financially stable and can make a profit,″ Turner said. ″The less growers need to spend on inputs like pesticides and fertilizers, the more money they’ll be able to save.″

Moving forward, Douches said additional Project GREEEN funds would be applied to hiring another graduate student to build upon the foundational work Kaiser started. While Kaiser helped find the gene to resistance against the Colorado potato beetle, insects and pathogens can adapt over time to overcome potato resistance.

″With breeding, you can’t say, ‘I’ve found this resistance gene — I’m all set now,’″ Douches said. ″Insects evolve. Pathogens evolve. You really need to continue feeding the system to develop broader resistance.″

As for-profit companies begin to explore diploid breeding, Turner said the studies conducted by Douches and his colleagues have helped the industry remain at the forefront of this research.

″Because of the work that was able to start so early through Project GREEEN, we’re ahead of the game in diploid breeding,″ Turner said. ″That really helps the industry move forward in our research without having to give it away to companies that are just coming onto the scene.″

Funds from Project GREEEN have helped Douches land larger, national grants to assist in breeding potatoes at the diploid level. In September 2023, Douches received a $1.14 million USDA NIFA Specialty Crop Research Initiative grant to continue his work on developing new varieties and breeding lines for potatoes in the north central U.S. In collaboration with North Dakota State University, the University of Minnesota and University of Wisconsin, Douches said MSU will unite with these fellow land-grant universities to develop breeding programs that’ll, in part, advance diploid breeding.

As MSU partners with these institutions, Turner said she gives credit to Project GREEEN’s grassroots contributions for creating an impact within and outside the state.

″The research that Project GREEEN funding helped to get started isn’t just helping Michigan,″ Turner said. ″It’s helping folks who have very similar growing climates, like those in the Great Lakes states and beyond.

″It definitely has far-reaching benefits.″