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 humble potato is a global crop coming third, after wheat and rice in terms of food production. The potato is also increasing in importance in the developing world due to its high nutritional value. Despite its familiarity, our cultivated potato has a surprisingly complex genome, making it very difficult to improve using traditional breeding techniques, with time spans of 10-15 years between the first cross and the final commercial cultivar. For this reason, over the last 100 years, improvements in key traits such as disease resistance, adaptation to climate change and yield, have been modest.
Hybrid breeding, a non-GMO technique, aided to quickly improve important traits in crops like maize, tomatoes, sorghum, cabbage, and sugar beet. The technique could also help to quickly develop new potato varieties that are adapted to 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, rather than 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.
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) rather than our cultivated potato, which 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 potato called Sli (S-locus inhibitor), says Richard Visser of 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 potato. 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.”
Ernst-Jan Eggers, genetics researcher for Solynta says 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,” he says. “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.”
