Yellow nutsedge is a specific plant species that contains significant amounts of both starch and oil as the main reserves in storage tuber. Its tuber can accumulate up to 35% oil of dry weight, perhaps the highest level observed in the tuber tissues of plant kingdom. To gain insight into the molecular mechanism that leads to high oil accumulation in yellow nutsedge, gene expression profiles of oil production pathways involved carbon metabolism, fatty acid synthesis, triacylglycerol synthesis, and triacylglycerol storage during tuber development were compared with purple nutsedge, a very close relative of yellow nutsedge that is poor in oil accumulation. Compared with purple nutsedge, the high oil content in yellow nutsedge was associated with much higher transcripts for seed-like oil-body proteins, almost all fatty acid synthesis enzymes, and specific key enzymes of plastid Rubisco bypass as well as malate and pyruvate metabolism. However, transcript levels for carbon metabolism toward pyruvate generation were comparable and for triacylglycerol synthesis were similar in both species. Two seed-like master transcription factors ABI3 and WRI1 were found to display similar temporal transcript patterns but be expressed at 6.5- and 14.3-fold higher levels in yellow nutsedge than in purple nutsedge, respectively. A weighted gene co-expression network analysis revealed that ABI3 is in strong transcriptional coordination with WRI1 and other key oil-related genes. Together, these results implied that plastidial pyruvate availability and fatty acid synthesis, along with triacylglycerol storage in oil body, rather than triacylglycerol synthesis in endoplasmic reticulum, are the major factors responsible for high oil production in tuber of yellow nutsedge, and ABI3 is most likely to play a critical role in regulating oil accumulation. This study will aid understanding in underlying molecular mechanism controlling carbon partitioning toward oil production in oil-rich tuber and provide valuable reference for enhancing oil accumulation in non-seed tissues of crops through genetic breeding or metabolic engineering.

中文翻译：

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与紫色紫苏相比，黄色紫苏的块茎中积累的油高，与参与脂肪酸合成和三酰甘油存储的基因的更丰富表达有关

黄nuts是一种特殊的植物物种，其中含有大量的淀粉和油脂，是块茎的主要储备。它的块茎最多可积累35％的干重油，这也许是植物界块茎组织中观察到的最高水平。为了深入了解导致黄色坚果中高油积累的分子机制，将与块茎发育过程中的碳代谢，脂肪酸合成，三酰甘油合成和三酰甘油贮藏有关的石油生产途径的基因表达谱与紫色坚果进行了比较，非常接近黄色积雪的亲戚，积油少。与紫色小坚果相比，黄色小坚果中的高油含量与种子状油体蛋白（几乎所有的脂肪酸合成酶）的转录本高得多有关，和质体Rubisco旁路的关键酶以及苹果酸和丙酮酸的代谢。然而，在两个物种中，碳代谢向丙酮酸生成的转录水平是可比较的，而三酰基甘油合成的转录水平是相似的。发现两个种子样的主转录因子ABI3和WRI1表现出相似的时间转录模式，但在黄色果中的表达水平分别比在紫色果中高6.5倍和14.3倍。加权基因共表达网络分析表明，ABI3与WRI1和其他关键的与油有关的基因处于强转录协调状态。总之，这些结果表明质体丙酮酸的可用性和脂肪酸的合成，以及三酰基甘油在油体中的储存，而不是内质网中的三酰基甘油的合成，是造成黄nuts块茎高产的主要因素，而ABI3最有可能在调节油的积累中起关键作用。这项研究将有助于理解控制富含碳的块茎中碳向油生产分配的分子机制，并为通过基因育种或代谢工程提高作物非种子组织中的油积累提供有价值的参考。