A Design III Study of Linkage Disequilibrium for Percent Oil in Maize¹

Abstract

The objectives of this study were 1) to estimate additive and dominance genetic variance and the average degree of dominance for percent oil in the F 2 and F 8 randommated generations of a cross between Illinois High Oil (IHO) and Illinois Low Oil (ILO) maize ( Zea mays L.) strains using Design III and 2) to measure the effect of linkage bias on such estimates. The following results were obtained: 1) The estimate of additive genetic variance was about eight ✕ larger than that of dominance genetic variance in the F 2 and about four ✕ larger in the F 6 ; 2) The estimate of additive variance in the F 8 was half that in the F 2 suggesting that many loci controlling percent oil were linked in the coupling phase in the parents; 3) The estimate of dominance variance in the F 6 did not differ from the F 2 indicating a lack of effect of linkage on dominance variance which could be interpreted as indicating that genes with dominant action are distributed throughout the genome with map distances approximating independent inheritance or that some genes are dominant for low oil while others are dominant for high oil; 4) Estimates of the average degree of dominance were 0.508 for the F 2 generation and 0.681 for the F 8 . Both estimates are significantly different from zero and from one, but not from each other.