There are three components that are critical to the KASP assay: 1) a purified DNA sample, 2) two allele-specific forward primers, and 3) a common reverse primer. A minimum of 5-10 ng of the extracted DNA sample are required for the method to function properly. The DNA sample is purified by adding a mixture of chemicals to the buffer solution.[2] In the first round of PCR, a KASP primer mix that contains the two allele-specific forward primers and the single reverse primer is added to the mixture. The specific nature of the forward primers allows for the primer to bind solely at the SNP of interest, allowing DNA polymerase to lay down the rest of the complementary nucleotides. During this time, the common reverse primer begins to lay down complementary nucleotides on the opposite strand of DNA. This ends the first round of PCR.[2]
In the second round of PCR, a compliment to the allele-specific forward primer is generated when the common reverse primer binds to the amplicon formed in the first round of PCR. Finally, the thermocycling of the PCR reaction continues, starting the third portion of the KASP method. The FAM oligo—a fluorescently labeled primer found in the master mix—complements the tail sequence of the common reverse primer, allowing for elongation to occur. This occurs multiple times throughout the thermocycling settings and the fluorescent signalling becomes stronger as more FAM oligo primers are used in the amplification process