TYPES OF GENE ACTION AT THREE GENE LOCI IN SUBLINES OF A MAIZE INBRED LINE

"Isogenic" lines of maize (Zea mays L.) inbred Hy, derived by backcrossing and differing by single marker genes and chromosome segments linked to these gene loci were used to study gene action in the inheritance of nine quantitative plant and ear characters. The 27 genotypes representing all combinations of the homozygous and heterozygous genotypes at the three loci, wx, br2, and rf2, were used. Highly significant differences among genotypes were observed for all characters studied. Frequencies of significant comparisons (P < 0.05) for the types of gene action were: additive, 74%; dominance, 74%; additive × additive. 78%; dominant × dominant, 70%; additive × dominant, 39%; additive × additive × additive, 67%; additive × additive × dominant, 30%; additive × dominant × dominant, 48%; dominant × dominant × dominant, 67%. Greatest effects were observed at the br2 segment; effects were greater at the rf1 segment than at the wx segment. Overdominance was significant for four characters at the wx segment, one character at the br2 segment, and three characters at the rf1 segment.