Enhanced seed oil content by overexpressing LPAAT and WRI1 genes in tobacco plant.

Key message: WRI1 and LPAAT gene overexpression enhances oil content and seed weight in tobacco plants, indicating potential candidate genes for enhancing seed oil in transgenic oil seed crops. The boosting triacylglycerols (TAG) assembly reactions (pull), the increasing fatty acid (FA) production (push), and the combination of these strategies were used to enhance seed oil content in transgenic tobacco plants. Three lines containing WRINKLED1 (WRI) (A1, A2, A7), two lines containing Lysophosphatidic Acid Acyltransferase (LPAAT) (B2, B3), and two lines containing WRI + LPAAT (AB1, AB2) transgenes were grown in greenhouse conditions and their T3 generations were used for further analysis. Total seed oil content in transgenic plants significantly increased within the range of 23.92-41%, respectively, in B3 and A7 lines than the non-transgenic tobacco plants. In addition, significantly elevated soluble sugar contents within 103.33-136.05 mg/g DW and 88.85-114.3 mg/g DW were observed, respectively, in the leaves and seeds of transgenic lines compared to control plants. We suggested that the enhanced accumulations of total soluble sugar in the seeds and leaves contribute to reallocation of the photosynthetic precursors for enhanced oil synthesis in transgenic plants. Expression analysis of WRI1 and LPAAT genes in transgenic plants showed a weak positive correlation with oil content (r ≈ 0.42). Overexpression of WRI1 and LPAAT increased seed size and weight, potentially explaining oil accumulation due to increased seed weight. Finally, no synergistic effect was observed in the simultaneous expression of WRI1 and LPAAT genes, suggesting potential limitations in the availability of oil biosynthesis precursors and interactions with other genes. Meanwhile, these findings show that WRI1 and LPAAT are reliable targets for genetic transformation of oil seed crops for improvement their seed oil yield.