Determining zygosity with multiplex Kompetitive Allele-Specific PCR (mxKASP) genotyping

We introduce multiplex Kompetitive Allele-Specific PCR (mxKASP): a modification of classical KASP genotyping that allows zygosity to be determined in diploid organisms. Rather than targeting a SNP associated with a single marker, mxKASP targets two non-homologous markers. We show proof of concept by applying mxKASP to the balanced lethal system in Triturus newts, in which individuals are known to possess either: (1) zero copies of the 1A version of chromosome 1 and two copies of the 1B version; (2) one copy of 1A and one copy of 1B; or (3) two copies of 1A and zero copies of 1B. mxKASP is successful in amplifying both a 1A and a 1B marker in a single reaction (if present), allowing the zygosity of individuals to be inferred. We independently confirm our mxKASP results with a multiplex PCR approach. We argue that mxKASP can be applied to rapidly and economically determine zygostity in diploid organisms, for a large number of samples at once.