Inheritance of High Oleic/Low Ricinoleic Acid Content in the Seed Oil of Castor Mutant OLE-1

Abstract

A mutant line of castor (Ricinus communis L.), OLE-1, was recently identified. It has a 20-fold increase in oleic acid (C18:1, about 780 g kg−1) and a six-fold decrease in ricinoleic acid content (C18:1-OH, about 140 g kg−1) compared with standard castor oil (C18:1, about 40 g kg−1; C18:1-OH, about 870 g kg−1). The objective of this research was to determine the inheritance of the high oleic/low ricinoleic trait in this mutant. Reciprocal crosses were made between the mutant OLE-1 and castor line A74/18/10 with standard composition. Although a slight maternal effect for oleic and ricinoleic content was observed in the analysis of F1 seeds, the genetic control was mainly embryonic. The standard oleic/ricinoleic content was dominant over high oleic/low ricinoleic content. Oleic acid content of F2 seeds segregated in bimodal patterns, each consistent with a ratio of 13 to 3 for low-intermediate oleic content (<110 g kg−1) to high oleic content (>650 g kg−1), respectively. This segregation was consistent with the action of two independent major genes (ol, Ml) with epistatic interaction. The high oleic/low ricinoleic phenotype was homozygous for the genotypes with the recessive allele ol, and heterozygous or homozygous for the dominant allele Ml The dominant allele Ml would release the action of the recessive allele ol, controlling the oleic and ricinoleic content. This model was confirmed in the BC1F1 to OLE-1, which segregated following a 1:1 (low-intermediate:high) ratio, and F3 segregations. The information provided by this genetic study will facilitate the transfer of the high oleic/low ricinoleic trait to castor cultivars.