PROGRESSIVE CONVERSION OF R-LOCUS EXPRESSION IN MAIZE

Abstract

A progressive change for the R-locus expression was demonstrated for the R allele when it was left heterozygous with a pattern allele for 2 or more generations. After 3 generations of heterozygosity with pattern alleles, 75% of the kernels carrying R were found to be completely colorless in testcrosses to recessive inbreds. Where R alleles are present in triploid aleuron tissue in 3 doses, 3 induction treatments made most of the kernels mottled or nearly colorless. R alleles which had undergone progressive induction were noted to give practically no reversion when homozygous. The findings of progressive changes in R can now explain previous anomalies reported for the R locus.