Partial Dominance, Pleiotropism, and Epistasis in the Inheritance of the High‐Oleate Trait in Peanut

Abstract

ABSTRACTEarlier reports of the high‐oleate (low‐linoleate) trait in peanut (Arachis hypogaea L.) indicated that it was controlled by completely dominant gene action. However, linoleate content intermediate to that in low‐ and normal‐linoleate seeds was found among progeny when the trait was backcrossed into five virginia‐type cultivars, suggesting partial dominance of the gene controlling the trait. Although BC1F2 results were inconsistent across recurrent parents, data from the BC2F2 and BC3F2 populations of all crosses conformed to the 1:2:1 ratio expected under partial dominance. Quantitative analysis showed that fatty acid levels were affected by the background genotypes of the recurrent parents, suggesting that there are other genes that influence fatty acid. The ol gene exhibited pleiotropism by influencing not only oleate and linoleate, but also levels of palmitate, total C18 fatty acids, gadoleate, and total saturated fatty acids. The effects of the ol gene interacted with background genotype, particularly with the additive genetic contrast, suggesting epistasis in the general sense. Progeny testing of 59 putatively heterozygous and 41 homozygous normal BC2F2 plants indicated that the two genotypes could be distinguished accurately on the basis of linoleate level, suggesting that the ol gene can be moved by backcrossing using techniques appropriate for a dominant trait rather than a recessive trait.