Identification of a novel variant lacking group A soyasaponin in a Chinese wild soybean (Glycine soja Sieb. & Zucc.): implications for breeding significance

Abstract

Group A saponins are the principal factors underlying the undesirable bitter and astringent tastes in soybean food products. Therefore, the genetic reduction or elimination of the undesirable tastes is of great significance in soybean taste breeding. Using thin‐layer chromatography and liquid chromatography–mass spectrometry, we identified a novel mutant lacking group A saponins in a wild soybean (Glycine soja Sieb. & Zucc.), reflecting the failed arabinose binding of arabinosyltransferase to the C‐22 hydroxyl group, consequently leading to a lack of group A saponins and the concomitance expression of two new components A‐αg and KA‐αg in seeds. The C‐3 glycosylated soyasapogenol A (SS‐A), A‐αg, is a steady precursor compound in biosynthesis of Aa and Ab types in the seeds of soybean plants and exhibits stable inheritance. In this study, we observed a critical step necessary for arabinose binding to the C‐22 hydroxyl group in the biosynthetic pathway of group A saponins and identified an important germplasm accession for the genetic improvement in the tastes of soybean milk and processed soybean foods.

The Effects of Domestication on Secondary Metabolite Composition in Legumes

“…In a study of seed saponin composition of 3,025 G. soja accessions, diverse compositions of seed saponins were found among the accessions (Krishnamurthy et al, 2013). Moreover, naturally occurring wild soybean mutants that lack group A saponins were found (Krishnamurthy et al, 2013;Takahashi et al, 2016;Rehman et al, 2018). Wild legumes do not necessarily have higher seed saponin contents.…”