Relationship between seed mass and linolenic acid in progeny of crosses between cultivated and wild soybean

Abstract

AbstractSoybean [Glycine max (L.) Merr.] oil from current commercial cultivars typically contains ca. 8% linolenic acid (18:3). Applications of plant biotechnology have enabled plant breeders to develop germplasm having as low as 2.0% 18:3. Oils that are naturally low in 18:3 exhibited improved flavor characteristics and greater oxidative stability in high‐temperature frying applications compared to hydrogenated soybean oil. As an extension of that research, efforts are underway to characterize genes in soybean that govern expression of higher than normal 18:3 concentration. Such oils may be of interest to the oleochemicals industry for various nonfood applications. Relatively high 18:3 in seed oil is a characteristic trait of the ancestor of modern soybean cultivars, Glycine soja (Sieb. and Zucc.). Accessions of this species have rarely been utilized in soybean improvement, and thus represent a virtually untapped genetic resource for genes governing 18:3 synthesis. We have hybridized cultivated soybean with wild soybean plant introductions. F3:4 seed from the resultant G. max × G. soja populations exhibited a wide segregation pattern for 18:3 and seed mass. A strong negative association was found between 18:3 concentration and seed mass. Oil concentration was positively correlated with seed mass. Evaluation of glycerolipid composition revealed that high 18:3 was not associated with an altered proportion of phospholipid and triacylglycerol among lines segregating for seed mass. Thus, smaller seed mass may be a convenient trait to distinguish future soybean cultivars with highly polyunsaturated oils from other cultivars in production.