Collage of Life Sciences, Chongqing Normal University, Chongqing, 401331, China.
BMC Genomics. 2018 Mar 21;19(1):213. doi: 10.1186/s12864-018-4595-z.
Perilla frutescens is well known for its high α-linolenic acid (ALA) accumulation in seeds and medicinal values as well as a source of edible and general-purpose oils. However, the regulatory mechanisms of the biosynthesis of fatty acid in its seeds remain poorly understood due to the lacking of sequenced genome. For better understanding the regulation of lipid metabolism and further increase its oil content or modify oil composition, time-course transcriptome and lipid composition analyses were performed.
Analysis of fatty acid content and composition showed that the α-linolenic acid and oleic acid accumulated rapidly from 5 DAF to 15 DAF and then kept relatively stable. However, the amount of palmitic acid and linoleic acid decreased quickly from 5 DAF to 15DAF. No significant variation of stearic acid content was observed from 5 DAF to 25DAF. Our transcriptome data analyses revealed that 110,176 unigenes were generated from six seed libraries at 5, 10, 20 DAF. Of these, 53 (31 up, 22 down) and 653 (259 up, 394 down) genes showed temporal and differentially expression during the seed development in 5 DAF vs 10 DAF, 20 vs 10 DAF, respectively. The differentially expressed genes were annotated and found to be involved in distinct functional categories and metabolic pathways. Deep mining of transcriptome data led to the identification of key genes involved in fatty acid and triacylglycerol biosynthesis and metabolism. Thirty seven members of transcription factor family AP2, B3 and NFYB putatively involved in oil synthesis and deposition were differentially expressed during seed development. The results of qRT-PCR for selected genes showed a strong positive correlation with the expression abundance measured in RNA-seq analysis.
The present study provides valuable genomic resources for characterizing Perilla seed gene expression at the transcriptional level and will extend our understanding of the complex molecular and cellular events of oil biosynthesis and accumulation in oilseed crops.
紫苏以其种子中高含量的α-亚麻酸（ALA）、药用价值以及食用和通用油源而闻名。然而，由于缺乏测序基因组，其种子中脂肪酸生物合成的调控机制仍知之甚少。为了更好地了解脂质代谢的调控，进一步提高其油含量或改变油的组成，进行了时间过程转录组和脂质组成分析。
脂肪酸含量和组成的分析表明，α-亚麻酸和油酸从 5 DAF 到 15 DAF 迅速积累，然后保持相对稳定。然而，棕榈酸和亚油酸的量从 5 DAF 到 15DAF 迅速减少。从 5 DAF 到 25DAF，硬脂酸的含量没有明显变化。我们的转录组数据分析显示，从六个种子文库中生成了 110176 个基因。其中，53 个（31 个上调，22 个下调）和 653 个（259 个上调，394 个下调）基因在 5 DAF 与 10 DAF、20 DAF 与 10 DAF 的种子发育过程中表现出时间和差异表达。差异表达基因被注释，并发现它们参与了不同的功能类别和代谢途径。对转录组数据的深入挖掘导致鉴定出参与脂肪酸和三酰基甘油生物合成和代谢的关键基因。在种子发育过程中，37 个假定参与油脂合成和沉积的转录因子家族 AP2、B3 和 NFYB 的成员差异表达。选定基因的 qRT-PCR 结果与 RNA-seq 分析中测量的表达丰度具有很强的正相关性。
本研究为在转录水平上表征紫苏种子基因表达提供了有价值的基因组资源，并将扩展我们对油料作物油脂生物合成和积累的复杂分子和细胞事件的理解。
