The TILLING-method has been modified for the potato. Key elements are the screening of mutant populations of diploid potatoes after mutations have been induced using Sanger-sequencing of the target gene. Different gene alleles can differ in their insertion/deletion
polymorphisms. These are especially found in the intron region.
To be able to definitely demonstrate possible mutations in the target gene of heterozygous organisms, the target gene alleles from both crossing partners have to carry the same InDel-pattern. If this is not the case, the sequences will shift against each other and can no longer be analyzed. In diploid potatoes the EMS-generated alleles can easily be detected by sequencing. This is because the new single nucleotide polymorphisms (SNPs) and the original sequence are found at a ratio of 1:1. Therefore, the seed production for EMS mutagenesis has to be done based on diploid parents. In addition, they have to be sexually compatible. This is not necessarily the case for diploid potatoes because of their system of gametophytic self-incompatibility.
Depending on the breeding goal the crossing partners are chosen from the segments fresh produce, processing, flakes, or starch of a diploid elite-breeding program. Thus, the new alleles are directly inserted into the desired genetic background. This is an important time-saving aspect of practical potato breeding.
The seeds that arise from this crossing will be treated with EMS. They are then used to establish a population of several thousand potato clones. These are obtained by vegetative reproduction. Sequencing the respective target gene of the individual EMS-clones is done by high through-put methods. The identified breeding clones with new alleles are then placed in tissue culture. Here with suitable methods the genomes are doubled. Tetraploid plants are generated and have direct application in practical potato breeding.