Styrax tonkinensis (Pierre) Craib ex Hartwich has great potential as a woody biodiesel species having seed kernels with high oil content, excellent fatty acid composition and good fuel properties. However, no transcriptome information is available on the molecular regulatory mechanism of oil accumulation in developing S. tonkinensis kernels. The dynamic patterns of oil content and fatty acid composition at 11 time points from 50 to 150 days after flowering (DAF) were analyzed. The percent oil content showed an up-down-up pattern, with yield and degree of unsaturation peaking on or after 140 DAF. Four time points (50, 70, 100, and 130 DAF) were selected for Illumina transcriptome sequencing. Approximately 73 million high quality clean reads were generated, and then assembled into 168,207 unigenes with a mean length of 854 bp. There were 5916 genes that were differentially expressed between different time points. These differentially expressed genes were grouped into 9 clusters based on their expression patterns. Expression patterns of a subset of 12 unigenes were confirmed by qRT-PCR. Based on their functional annotation through the Basic Local Alignment Search Tool and publicly available protein databases, specific unigenes encoding key enzymes, transmembrane transporters, and transcription factors associated with oil accumulation were determined. Three main patterns of expression were evident. Most unigenes peaked at 70 DAF, coincident with a rapid increase in oil content during kernel development. Unigenes with high expression at 50 DAF were associated with plastid formation and earlier stages of oil synthesis, including pyruvate and acetyl-CoA formation. Unigenes associated with triacylglycerol biosynthesis and oil body development peaked at 100 or 130 DAF. Transcriptome changes during oil accumulation show a distinct temporal trend with few abrupt transitions. Expression profiles suggest that acetyl-CoA formation for oil biosynthesis is both directly from pyruvate and indirectly via acetaldehyde, and indicate that the main carbon source for fatty acid biosynthesis is triosephosphate originating from phosphohexose outside the plastid. Different sn-glycerol-3-phosphate acyltransferases are implicated in diacylglycerol biosynthesis at early versus late stages of oil accumulation. Triacylglycerol biosynthesis may be accomplished by both diacylglycerol and by phospholipid:diacylglycerol acyltransferases.

中文翻译：

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转录的转录途径分析与油脂积累相关的发育种子的圆柏（Styrax tonkinensis），一种木本生物柴油物种。

产自东北哈特威奇（Syryrax tonkinensis（Pierre）Craib）的木质生物柴油品种具有很大的潜力，其籽粒具有高油含量，出色的脂肪酸组成和良好的燃料特性。但是，尚无转录组信息可了解发育中的S. tonkinensis仁中油积累的分子调控机制。分析了开花后50至150天（DAF）在11个时间点的油含量和脂肪酸组成的动态模式。含油百分率呈自上而下的模式，产量和不饱和度在140 DAF或之后达到峰值。选择了四个时间点（50、70、100和130 DAF）进行Illumina转录组测序。产生了约7300万个高质量的纯净读段，然后组装成168207个单基因，平均长度为854 bp。有5916个基因在不同时间点之间差异表达。这些差异表达的基因根据其表达模式分为9个簇。通过qRT-PCR确认了12个单基因的子集的表达模式。基于它们通过基本局部比对搜索工具的功能注释和可公开获得的蛋白质数据库，确定了编码关键酶，跨膜转运蛋白和与油积累相关的转录因子的特定单基因。三种主要的表达方式是显而易见的。大多数单基因在70 DAF达到峰值，这与籽粒发育过程中油含量的快速增加相吻合。在50 DAF时高表达的单基因与质体形成和油合成的早期阶段（包括丙酮酸和乙酰辅酶A形成）相关。与三酰基甘油生物合成和油体发育相关的单基因在100或130 DAF达到峰值。石油积累过程中的转录组变化表现出明显的时间趋势，几乎没有突变。表达谱表明，用于油类生物合成的乙酰辅酶A既直接来自丙酮酸，也间接通过乙醛形成，表明脂肪酸生物合成的主要碳源是源自质体外部磷酸己糖的磷酸三糖。在油积累的早期与晚期，不同的sn-甘油-3-磷酸酰基转移酶与二酰基甘油的生物合成有关。三酰基甘油的生物合成可以通过二酰基甘油和磷脂：二酰基甘油酰基转移酶来完成。石油积累过程中的转录组变化表现出明显的时间趋势，几乎没有突变。表达谱表明，用于油类生物合成的乙酰辅酶A既直接来自丙酮酸，也间接通过乙醛形成，表明脂肪酸生物合成的主要碳源是源自质体外部磷酸己糖的磷酸三糖。在油积累的早期与晚期，不同的sn-甘油-3-磷酸酰基转移酶与二酰基甘油的生物合成有关。三酰基甘油的生物合成可以通过二酰基甘油和磷脂：二酰基甘油酰基转移酶来完成。石油积累过程中的转录组变化表现出明显的时间趋势，几乎没有突变。表达谱表明，用于油类生物合成的乙酰辅酶A既直接来自丙酮酸，也间接通过乙醛形成，表明脂肪酸生物合成的主要碳源是源自质体外部磷酸己糖的磷酸三糖。在油积累的早期与晚期，不同的sn-甘油-3-磷酸酰基转移酶与二酰基甘油的生物合成有关。三酰基甘油的生物合成可以通过二酰基甘油和磷脂：二酰基甘油酰基转移酶来完成。表达谱表明，用于油类生物合成的乙酰辅酶A既直接来自丙酮酸，也间接通过乙醛形成，表明脂肪酸生物合成的主要碳源是源自质体外部磷酸己糖的磷酸三糖。在油积累的早期与晚期，不同的sn-甘油-3-磷酸酰基转移酶与二酰基甘油的生物合成有关。三酰基甘油的生物合成可以通过二酰基甘油和磷脂：二酰基甘油酰基转移酶来完成。表达谱表明，用于油类生物合成的乙酰辅酶A既直接来自丙酮酸，也间接通过乙醛形成，表明脂肪酸生物合成的主要碳源是源自质体外部磷酸己糖的磷酸三糖。在油积累的早期与晚期，不同的sn-甘油-3-磷酸酰基转移酶与二酰基甘油的生物合成有关。三酰基甘油的生物合成可以通过二酰基甘油和磷脂：二酰基甘油酰基转移酶来完成。在油积累的早期与晚期，不同的sn-甘油-3-磷酸酰基转移酶与二酰基甘油的生物合成有关。三酰基甘油的生物合成可以通过二酰基甘油和磷脂：二酰基甘油酰基转移酶来完成。在油积累的早期与晚期，不同的sn-甘油-3-磷酸酰基转移酶与二酰基甘油的生物合成有关。三酰基甘油的生物合成可以通过二酰基甘油和磷脂：二酰基甘油酰基转移酶来完成。