Peer review

When two paramutable R alleles differing in aleurone pigmenting potential and designated R1 and R2 are combined as R1R2 heterozygotes, the pigmenting capacity of the stronger R allele declines toward that of its weaker partner. After several generations in R1R2 heterozygous stacks, the expression of the two alleles are indistinguishable. The property of a paramutable R allele to cause the reduction in the expression of a stronger allele is almost certainly inherent in the allele, and is present in alleles that have no known history of heterozygosity with the strongly paramutagenic alleles such as stippled (Rst) . The parallel between this type of interaction and the interaction previously described as secondary paramutation, occurring between a paramutable R allele and a paramutant R' derived from R Rst plants, is thought to be significant. The paramutagenicity of an R' factor may be regarded as the enhancement of a property normally present in the allele and not as an acquisition of some part of the paramutagenic properties of stippled.

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