Inheritance of low linolenic acid level in the soybean line RG10

Relatively high linolenic acid content (80-100 g kg(-1)) in soybean [Glycin e max (L.) Merr.] cultivars is the most important factor eon tributing to o xidative instability of soybean oil. Mutation breeding was used to develop soybean line RG10 with reduced linolenic acid content (<25 g kg(-1)). The u sefulness of this line in a breeding program designed to reduce linolenic a cid 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 ac id level in RG10. The F-2 and F-3 progenies from crosses RG10 x C1640 and R G10 x 'Century' segregated in trimodal fashion. On the basis of chi-square analyses of F-2 seeds and F-3 families from RG10 x C1640 and F-3 families f rom RG10 x Century cross, the observed frequency distributions significantl y 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 I;an locus. This alle le 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 f or very low (<25 g kg(-1)) level of linolenic acid in RG10. The simple inhe ritance of the low level of linolenic acid makes RG10 an ideal parent in br eeding programs aimed at improving oil quality in soybean.