An α/β-Hydrolase GmABHD6 Controls Seed Oil Content and Yield in Soybean.

Seed oil content is a key trait in soybean, yet its genetic basis remains largely unresolved. Here, we identify GmABHD6, an α/β-hydrolase domain-containing gene, as the causal gene underlying a major quantitative trait locus (QTL) for seed oil content on chromosome 16. Through fine-mapping in a chromosome segment substitution population derived from Glycine max (SN14) and wild Glycine soja (ZYD00006), we fine-mapped the QTL to a 150-kb interval. Functional analyses reveal that overexpression of GmABHD6 significantly reduces seed oil content, whereas gene editing to truncate GmABHD6 led to increased oil accumulation. These modifications also alter seed protein levels, seed size and 100-seed weight, indicating pleiotropic effects on seed composition and yield traits. Integrated transcriptomic and metabolomic profiling of transgenic lines highlighted widespread changes in lipid metabolism and energy pathways associated with GmABHD6 activity. Further functional characterisation indicates that the ERF transcription factor GmERF physically binds to the GmABHD6 promoter region to regulate its expression. Population genetic analyses show strong signatures of selection at the GmABHD6 locus, suggesting that favourable alleles are enriched during soybean domestication and improvement. Our findings establish GmABHD6 as a domestication-related gene that negatively regulates seed oil content and provide new insights into the genetic mechanisms driving soybean seed composition and evolution.