Suppression of randomly primed polymerase chain reaction products (random amplified polymorphic DNA) in heterozygous diploids

In a study of genetic polymorphism in the gypsy moth Lymantria dispar we ob served the aberrant inheritance of a random amplified polymorphic DNA (RAPD ) fragment designated H11-589. This fragment was present in amplification p roducts of F-1 progeny of different crosses although it was not amplified f rom either parental DNA. DNA-mixing experiments revealed that the presence of DNA containing a template for another product (H11-746), amplified with the same primer, suppressed the synthesis of H11-589. The templates for bot h RAPD products were highly repetitive and scattered throughout the L. disp ar genome. Southern hybridization and sequence analysis of H11-746 and H11- 589 revealed an extensive sequence homology and an internal repetitive moti f of 17 nucleotides present in both products. Interactions between template s for H11-746 and H11-589 are expected to occur during the polymerase chain reaction (PCR), offering an explanation for the suppression of the amplifi cation of H11-589. The role of the internal repetitive motif and of the cop y number of both templates in the suppression effect are discussed. Our res ults corroborate doubts regarding the suitability of the RAPD technique for quantitative genetic analysis, in particular where mixed populations are c oncerned.