Genetic Analysis of Low Linolenic Acid Levels in the Soybean Line PI 361088B

The soybean (Glycine max (L.) Merr.) line PI 361088B was identified as having a linolenic acid level (38.1 g kg−1) that was about half that of ‘Maple Arrow’ (78.1 g kg−1), but similar to that of the mutagen‐induced line C1640 (37.6 g kg−1). Our objective was to determine the inheritance of low linolenic acid levels in PI 361088B, and to determine the genetic basis of this trait relative to the Fan locus known to influence linolenic acid levels in C1640. The F2 and F3 segregation data from crosses between PI 361088B and Maple Arrow or ‘Ace’, indicate that linolenic acid levels in PI 361088B are influenced by alleles, at a single locus, acting in an additive manner. Crosses were made between C1640 and a low linolenic acid selection from a three‐way cross involving PI 361088B. The F2 progeny of the cross, [(Ace ✕ PI 361088B) ✕ OAC 84‐06] ✕ C1640, did not segregate for linolenic acid levels indicating that the low levels in both PI 361088B and C1640 are controlled by alleles at the same locus. A linkage assay indicated that the Fan locus segregates independently of the Dial, Enp, Idh1, and Pgm1 loci, and that the Fan locus is linked to the Idh2 locus with a recombination frequency of 28.2 ± 2.7%. No other linkages have been established for these two loci; they therefore are assigned to linkage group 17.