Soybean oil is one of the most consumed vegetable oils worldwide. Genetic improvement of its concentration in seeds has been historically pursued due to its direct association with its market value. Engineering attempts aiming to increase soybean seed oil presented different degrees of success that varied with the genetic design and the specific variety considered. Understanding the embryo’s responses to the genetic modifications introduced, is a critical step to successful approaches. In this work, the metabolic and transcriptional responses to AtWRI1 and AtDGAT1 expression in soybean seeds were evaluated. AtWRI1 is a master regulator of fatty acid (FA) biosynthesis, and AtDGAT1 encodes an enzyme catalysing the final and rate-limiting step of triacylglycerides biosynthesis. The events expressing these genes in the embryo did not show an increase in total FA content, but they responded with changes in the oil and carbohydrate composition. Transcriptomic studies revealed a down-regulation of genes putatively encoding for oil body packaging proteins, and a strong induction of genes annotated as lipases and FA biosynthesis inhibitors. Novel putative AtWRI1 targets, presenting an AW-box in the upstream region of the genes, were identified by comparison with an event that harbours only AtWRI1. Lastly, targeted metabolomics analysis showed that carbon from sugar phosphates could be used for FA competing pathways, such as starch and cell wall polysaccharides, contributing to the restriction in oil accumulation. These results allowed the identification of key cellular processes that need to be considered to break the embryo’s natural restriction to uncontrolled seed lipid increase.

中文翻译：

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大豆胚胎发育过程中AtWRI1和AtDGAT1的表达影响油脂和碳水化合物代谢


大豆油是全球消费量最大的植物油之一。由于其与市场价值直接相关，其在种子中的浓度的遗传改良历来一直被追求。旨在增加大豆籽油的工程尝试取得了不同程度的成功，具体程度因基因设计和所考虑的具体品种而异。了解胚胎对引入的基因修饰的反应是成功方法的关键一步。在这项工作中，评估了大豆种子中AtWRI1和AtDGAT1表达的代谢和转录反应。 AtWRI1是脂肪酸 (FA) 生物合成的主要调节因子， AtDGAT1编码一种酶，可催化三酰甘油生物合成的最终限速步骤。在胚胎中表达这些基因的事件并未显示总 FA 含量的增加，但它们通过油和碳水化合物成分的变化做出反应。转录组学研究揭示了油体包装蛋白编码基因的下调，以及脂肪酶和 FA 生物合成抑制剂基因的强烈诱导。通过与仅包含AtWRI1的事件进行比较，鉴定出新的假定 AtWRI1 靶点，在基因的上游区域呈现 AW 盒。最后，靶向代谢组学分析表明，糖磷酸盐中的碳可用于 FA 竞争途径，例如淀粉和细胞壁多糖，从而有助于限制油脂积累。这些结果使得能够识别关键的细胞过程，需要考虑这些过程来打破胚胎对不受控制的种子脂质增加的自然限制。