Researchers at the hybrid potato breeding company Solynta and Wageningen University & Research have identified, cloned and characterized the gene for self-compatibility in potatoes called Sli (S-locus inhibitor). This discovery will have a profound impact on potato breeding. With Sli defined, breeders can implement hybrid breeding, which will allow for faster and focused, rather than opportunistic, breeding. This focused breeding can quickly bring new resilient and nutritious varieties to the market that will help make potato production become more sustainable. The result of the team’s molecular analysis of Sli has been published in the scientific journal Nature Communications.

The potato is increasing in importance in the developing world due to its high nutritional value. Despite its familiarity, the cultivated potato has a surprisingly complex genome, making it very difficult to improve using traditional breeding techniques, with time spans of 10 to 15 years between the first cross and the final commercial cultivar. For this reason, over the last 100 years, only modest improvements have been made in key traits such as disease resistance, adaptation to climate change and yield.

Hybrid Breeding

Hybrid breeding—a non-GMO technique—has helped plant breeders to quickly improve important traits in crops like corn, tomatoes, sorghum, cabbage and sugarbeets. The technique could also aid in quickly developing new potato varieties adapted to specific local conditions such as drought or flooding. Another big advantage is the fact that hybrid potato varieties grow from true seeds instead of the traditional bulky seed tubers. These seeds are disease-free and need less chemical protection after they have been planted in the field. Also, unlike bulky seed tubers, the seeds can be more easily stored and transported to potato growers. Hybrid potato breeding could therefore contribute to food security and a more sustainable food supply in large parts of the world.

The Solynta agronomy team plants potato trials in the Netherlands.

Sli Gene

Hybrid potato breeding is based on the cross-breeding of diploid potatoes, in which every cell contains two complete sets of chromosomes (one from each parent). This is in contrast to traditionally cultivated potatoes, whose complex genome consists of four sets of chromosomes. In order to actually capitalize on the opportunities of hybrid potato breeding, it was crucial to identify, clone and characterize the key gene for self-compatibility in potatoes. This gene is called Sli (S-locus inhibitor), says Richard Visser, a professor for the plant breeding group of Wageningen University & Research (WUR).

“An important element of hybrid breeding is the fixation of traits of the two parental lines through inbreeding,” Visser says. “In the course of evolution, many plants, including almost all diploid potatoes, have prevented inbreeding by becoming self-incompatible. But we are now able to overcome this through the Sli gene in potatoes. Self-compatibility as such and also the location on Chromosome 12 were already known for some time, but so far the gene encoding this trait was unknown and had not been isolated and characterized. Through genetic analysis and genome sequencing, we’ve succeeded in doing this. This now gives us the key to fast and effective breeding of new diploid potatoes.”

Solynta genetic researcher Ernst-Jan Eggers explains the company is “already using the Sli gene by crossing self-incompatible diploid lines with a Sli gene donor. With these new insights, we may be able to discover new variants of Sli that could improve our ability to select for improved taste, water use efficiency, disease resistances and other characteristics for our ever-changing world. This knowledge will deepen our understanding of self-incompatibility systems, which is important from a fundamental scientific perspective, but may have real-world implications in the breeding of not just potato, but also other Solanaceous crops such as tomato, eggplant and pepper.”

Nature Communications

The work of Solynta and WUR has been described in the scientific journal Nature Communications, where the authors further describe how the discovery will profoundly impact in the speed of breeding and focus of potato breeding.

Solynta and WUR have worked together extensively in the past and will continue to build on their successes. This discovery is the most recent in their successful public-private collaboration. Now that the self-incompatibility has been solved together, the teams can aim their research interests at solving other issues which will leverage their unique skills. Ultimately the collaboration will provide improved potatoes that use fewer chemicals and are better adapted to a constantly changing climate and customer base.