Precision Breeding in Potato: Towards Enhanced Resistance Using New Breeding Techniques

Potatoes (Solanum tubersosum) is the most important non-cereal crop worldwide measured by human consumption. Production of potatoes for the starch industry and for consumption is challenged by a wide range of pests such as the early and late blight pests. Farmers seek to control these two pests manly by applying pesticides and thereby jeopardize the surrounding environment and drinking water. The intensive pesticide usage must be reduced to meet the demands for food safety, clean drinking water and preservation of biodiversity. Breeders have introduced resistance genes from wild Solanum relatives into elite cultivars through the use of conventional breeding methods to gain resistance against primarily the late blight pest. This strategy has been effective, but the resistance has fast been overcome by the pathogen. In recent years, loss of gene rather than gain of gene, has emerged as a new and promising approach. The genes in question have been denominated “plant susceptibility genes”, a category of genes that are often utilised by the pathogen during different stages of the infection to aid the pathogenesis. New breeding techniques such as CRISPR-Cas has enabled precise gene editing in complex and high ploidy genomes such as the potato genome and CRISPR-Cas mediated knockout of susceptibility genes has become a new tool in the toolbox for controlling the late blight pest.
This thesis describes my efforts and contributions in establishing schemes for efficient gene editing by CRISPR-Cas and regeneration of mutant potato ex-plants with elevated tolerance towards potato pathogens such as late blight.