Breeding Potatoes at the Diploid Level
With four sets of chromosomes, tetraploid potatoes make up the majority of potatoes farmed worldwide. This increases the amount of genes that need to be crossed, which makes breeding potatoes very challenging.
Professor Dave Douches of MSU’s Department of Plant, Soil, and Microbial Sciences realized the importance of locating the genetic material required to cultivate a diploid potato – a potato with just two sets of chromosomes – during his tenure as director of the Solanaceae Coordinated Agricultural Project (SolCAP).
While both diploid and tetraploid potatoes came from South America centuries ago, it was the tetraploid that eventually made its way to the world market and is the variety that people usually purchase 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, according to an MSU article recently published.
Genetic progress can occur rapidly thanks to diploid breeding. Scientists have a higher chance of reaching desired features when editing genes at the diploid level as opposed to the tetraploid level.
In 2018, Douches sought and was awarded Project GREEN funding to assist in the beginning of this project.
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. It’s been crucial work because we’ve been taking advantage of modern technology and gene editing to impart self-compatibility in diploid potatoes,” Douches declared.
The ability of a plant to pollinate itself using its seeds and fruits is known as self-compatibility. Before the study supported by Project GREEEN, diploid potatoes lacked the self-compatibility characteristic. It’s a feasible option now that could make it easier and faster to develop a wide variety of diploid potatoes.
According to Douches, he and his colleagues are getting ready to petition the USDA. If approved, this would free the gene-edited potato with self-compatibility from regulations with just minor limitations – akin to the rules that apply to conventional foods.
Project GREEEN funding has enabled Douches to secure larger, national grants to support diploid potato breeding. Douches was awarded a USD1.14m USDA NIFA Specialty Crop Research Initiative grant in September 2023 to carry out his research on creating new potato varieties and breeding lines in the north-central United States. Douches added that MSU will work with the University of Minnesota, the University of Wisconsin, and North Dakota State University to establish breeding initiatives that will, in part, promote diploid breeding.
