Plant Genome III Conference Plant Genome III Conference
Ten codominant RAPD markers were identified in mapping populations of chickpea (Cicer ariefinwn L.)and diploid strawberry (Fragaria wsca). A common feature of all ten markers, and perhaps of codominant RAPD markers in general, was the presence in heterozygous individuals of a non-parental, heteroduplex band migrating more slowly than either of the respective parental bands. This non-parental band could also be generated by mixing parental DNAs before PCR (template mixing). We explored template mixing as a means of identifying primers that would detect codominant RAPD markers in a particular mapping population. Two parental DNAs and a 1:1 mixture of parental DNAs were used as templates with each of twenty previously untested 10-base oligomers. Parental and respective mixed template gel lanes were compared to allow identification of non-parental bands in the mixed-template lanes. Four primers produced a total of five non-parental, heteroduplex bands in mixed template reactions. These primers were then used to detect five segregating, codominant markers and nine dominant markers in the respective F2 mapping population, a codominant marker frequency of 35.7%. When closely migrating fast and slow bands of co-dominant RAPDs were difficult to differentiate, parent-progeny template mixing was used to deliberately generate heteroduplex bands in fast or slow band F2 homozygotes, respectively, allowing confirmation of marker phenotype.