莲藕酚类物质组成分析及合成机制研究

Analysis of phenolic composition and synthesis mechanism of Nelumbo nucifera

中文关键词:  莲藕  酚类物质  组成  基因表达

英文关键词:Nelumbo nucifera  phenolic composition  composition  gene expression

中文摘要:

      目的 分析莲藕采前不同时期酚类物质的组成, 筛选莲藕特征酚类物质代谢相关基因及转录因子。方法 本研究以“鄂莲五号”为试材, 基于高效液相色谱及转录组学解析莲藕采前特征酚类物质代谢及转录组调控相关基因。结果 不同生长期莲藕褐变度呈上升趋势, 其总酚含量先增加后减少, S3(生长期3)时期总酚含量达到最高峰为16.59 mg GAE/100 g。其中酚类物质含量最高的是天麻素, 在S4时期含量达到最高峰为191.44 μg/g。苯丙烷和类黄酮代谢途径中参与天麻素、没食子儿茶素、儿茶素合成的基因在莲藕根茎膨大早期和中期高表达。利用实时荧光定量聚合酶链式反应验证转录组分析检测到的酚类化合物生物合成所需的几个差异表达基因。27个转录因子家族在莲藕生长期显著差异表达, 其中Nn_104608167(AP2-EREBP)、Nn_104608008(MYB)、Nn_104593222(bHLH)、Nn_104594756(C2C2-Dof)表达变化与生长期莲藕酚类物质含量变化模式相一致。结论 莲藕生长期酚类物质的不断积累, 导致褐变度呈现出不断上升趋势。27个转录因子家族的部分基因表达量与生长期莲藕酚类物质变化趋势相一致, 可能参与了酚类物质的转录调控。本实验为进一步研究莲藕酚类物质变化提供分子水平的理论基础。

英文摘要:

      Objective To analyze the phenolic composition of Nelumbo nucifera at different pre-harvest periods and to screen for genes and transcription factors related to the metabolism of characteristic phenolic substances in Nelumbo nucifera. Methods In this study, the genes related to the metabolism of phenolics and transcriptome regulation of Nelumbo nucifera before harvest were analyzed by high performance liquid chromatography and transcriptomics using Nelumbo nucifera of Elian No.5 as the test material. Results The browning degree of Nelumbo nucifera showed an increasing trend at different growth stages, and its total phenolic content first increased and then decreased, reaching a peak of 16.59 mg GAE/100 g at S3 (growth stage 3). The highest phenolic content was found in asparagine, which peaked at 191.44 μg/g during the S4 period. Genes involved in the synthesis of gastrodin, epigallocatechin and catechin in the phenylpropane and flavonoid metabolic pathways were highly expressed in the early and middle stages of rhizome enlargement of Nelumbo nucifera. Several differentially expressed genes required for phenolic compound biosynthesis detected by transcriptome analysis were validated using quantitative real-time polymerase chain reaction. Twenty-seven transcription factor families were significantly differentially expressed during the growing phase of Nelumbo nucifera, including Nn_104608167(AP2-EREBP), Nn_104608008(MYB), Nn_104593222(bHLH), Nn_104594756(C2C2-Dof) expression changes were consistent with the pattern of phenolic content changes in Nelumbo nucifera during the growth period. Conclusion The accumulation of phenolics in Nelumbo nucifera during the growing period lead to a rising trend of browning. The expression of some genes of 27 transcription factor families is consistent with the changing trend of phenolics in Nelumbo nucifera during the growing period and may be involved in the transcriptional regulation of phenolics. This experiment provides a theoretical basis for further study of phenolic substance changes in Nelumbo nucifera at the molecular level.