A TgWRKY1−TgGPAT1 regulatory module promotes oil biosynthesis in Torreya grandis kernels

Torreya grandis , a rare woody oil crop endemic to China, features drupe-like seeds with oil-rich kernels. Its oil contains abundant fatty acids, particularly unsaturated fatty acids, which confer considerable economic value due to their hypolipidemic and antioxidant activities. However, the regulatory network underlying oil biosynthesis in T. grandis remains largely unknown. In this study, TgGPAT1 expression was markedly elevated during kernel development, accompanied by rapid oil accumulation, with tissue-specific expression analysis showing the highest expression in the kernel. Subcellular localization analysis indicated the mitochondrial localization of TgGPAT1. Functional validation of TgGPAT1 in Arabidopsis thaliana and T. grandis kernels demonstrated that TgGPAT1 overexpression in A. thaliana increased oil content, whereas the transient expression of TgGPAT1 in T. grandis kernels significantly promoted oil accumulation. Fatty acid analysis further revealed altered fatty acid composition and increased total unsaturated fatty acid content in TgGPAT1 -overexpressing kernels. Moreover, the transcription factor TgWRKY1 directly regulated TgGPAT1 expression, thereby promoting oil accumulation and modulating the fatty acid profile to increase the proportion of unsaturated fatty acids. Together, these findings advance our understanding of the regulatory mechanisms underlying oil accumulation in T. grandis and facilitate the development of varieties with enhanced oil production and improved unsaturated fatty acid composition.