Inheritance of Low Linolenic Acid Level in the Soybean Line RG10

Abstract

Relatively high linolenic acid content (80–100 g kg−1) in soybean [Glycine max (L.) Merr.] cultivars is the most important factor contributing to oxidative instability of soybean oil. Mutation breeding was used to develop soybean line RG10 with reduced linolenic acid content (<25 g kg−1). The usefulness of this line in a breeding program designed to reduce linolenic acid content would depend on the complexity of inheritance of linolenic acid level. The objective of our study was to determine the number of loci and type of gene action associated with the inheritance of reduced linolenic acid level in RG10. The F2 and F3 progenies from crosses RG10 × C1640 and RG10 × ‘Century’ segregated in trimodal fashion. On the basis of chi‐square analyses of F2 seeds and F3 families from RG10 × C1640 and F3 families from RG10 × Century cross, the observed frequency distributions significantly fit a 1:2:1 ratio. These results indicate that the low level of linolenic acid in RG10 is controlled by a mutant allele at the Fan locus. This allele shows additive gene action when combined with the fan allele from C1640 and the Fan allele from Century. The gene symbol fan‐b fan‐b was assigned for very low (<25 g kg−1) level of linolenic acid in RG10. The simple inheritance of the low level of linolenic acid makes RG10 an ideal parent in breeding programs aimed at improving oil quality in soybean.