ABSTRACT Soybean is a major crop that produces high‐quality seed oil for global consumption. However, the regulatory mechanisms underlying seed oil content remain poorly understood. In this study, GmGT‐2F , a trihelix transcription factor, was identified as a positive regulator of seed oil content. It was observed that GmGT‐2F expression gradually increased during seed development. Furthermore, GmGT‐2F overexpression elevated seed oil content and increased the proportion of oleic and linoleic acids in fatty acid composition. However, knocking out GmGT‐2F improved seed protein content and seed size. We demonstrated that GmGT‐2F binds to the GmAGAL promoter and activates its transcription. Moreover, knockout of GmAGAL and GmGT‐2F / GmAGAL reduced α‐galactosidase activity and decreased seed oil content. The metabolomic and seed sucrose content analyses of the gmagal and wild‐type (WT) plants showed that GmGT‐2F affects the transcription of GmAGAL to regulate the activity of α ‐galactosidase and may control the oil content by influencing the generation and distribution of sucrose in the seed. In addition, GmCYP2 interacts with GmGT‐2F, reducing its promoter‐binding activity and inhibiting GmAGAL transcription. Haplotype diversity analyses of GmGT‐2F , GmCYP2 , and GmAGAL revealed combinations associated with increased oil or protein content. This study elucidates the regulatory mechanism by which GmGT‐2F regulates seed oil content, expands understanding of trihelix transcription factor function in seed quality trait regulation, and provides new insights for high‐quality soybean breeding.
Li et al. (Wed,) studied this question.