Engineering Research Centre of Ecology and Agricultural Use of Wetland, Ministry of Education/Hubei Collaborative Innovation Center for Grain Industry, Yangtze University, Jingzhou, China.
Food Crops Institute, Hubei Academy of Agricultural Sciences/Hubei Engineering and Technology Research Centre of Sweet Potato/Hubei Key Laboratory of Food Crop Germplasm and Genetic Improvement, Wuhan, China.
PLoS One. 2021 Jan 22;16(1):e0245266. doi: 10.1371/journal.pone.0245266. eCollection 2021.
Leafy sweet potato is rich in total phenolics (TP) which play key roles in health protection, the chlorogenic acid (CGA) constitutes the major components of phenolic compounds in leafy sweet potato. Unfortunately, the mechanism of CGA biosynthesis in leafy sweet potato is unclear. To dissect the mechanisms of CGA biosynthesis, we performed transcriptome, small RNA (sRNA) and degradome sequencing of one low-CGA content and one high-CGA content genotype at two stages. A total of 2,333 common differentially expressed genes (DEGs) were identified, and the enriched DEGs were related to photosynthesis, starch and sucrose metabolism and phenylpropanoid biosynthesis. The functional genes, such as CCR, CCoAOMT and HCT in the CGA biosynthetic pathway were down-regulated, indicating that the way to lignin was altered, and two possible CGA biosynthetic routes were hypothesized. A total of 38 DE miRNAs were identified, and 1,799 targets were predicated for 38 DE miRNAs by using in silico approaches. The target genes were enriched in lignin and phenylpropanoid catabolic processes. Transcription factors (TFs) such as apetala2/ethylene response factor (AP2/ERF) and Squamosa promoter binding protein-like (SPL) predicated in silico were validated by degradome sequencing. Association analysis of the DE miRNAs and transcriptome datasets identified that miR156 family negatively targeted AP2/ERF and SPL. Six mRNAs and six miRNAs were validated by qRT-PCR, and the results showed that the expression levels of the mRNAs and miRNAs were consistent with the sequencing data. This study established comprehensive functional genomic resources for the CGA biosynthesis, and provided insights into the molecular mechanisms involving in this process. The results also enabled the first perceptions of the regulatory roles of mRNAs and miRNAs, and offered candidate genes for leafy sweet potato improvements.
叶用甘薯富含总酚（TP），TP 在保护健康方面起着关键作用，绿原酸（CGA）构成叶用甘薯中酚类化合物的主要成分。不幸的是，叶用甘薯中 CGA 生物合成的机制尚不清楚。为了剖析 CGA 生物合成的机制，我们在两个阶段对一个低 CGA 含量和一个高 CGA 含量基因型进行了转录组、小 RNA（sRNA）和降解组测序。总共鉴定了 2333 个共同差异表达基因（DEGs），富集的 DEGs 与光合作用、淀粉和蔗糖代谢以及苯丙烷生物合成有关。CGA 生物合成途径中的功能基因，如 CCR、CCoAOMT 和 HCT 下调，表明木质素的途径发生了改变，并假设了两种可能的 CGA 生物合成途径。总共鉴定了 38 个差异表达 miRNA，通过计算方法预测了 38 个 DE miRNA 的 1799 个靶标。靶基因富集在木质素和苯丙烷代谢过程中。通过计算方法预测的转录因子（TFs），如 AP2/乙烯响应因子（AP2/ERF）和 Squamosa 启动子结合蛋白样（SPL）在降解组测序中得到了验证。DE miRNA 和转录组数据集的关联分析表明，miR156 家族负向靶向 AP2/ERF 和 SPL。通过 qRT-PCR 验证了 6 个 mRNA 和 6 个 miRNA，结果表明这些 mRNA 和 miRNA 的表达水平与测序数据一致。本研究为 CGA 生物合成建立了全面的功能基因组资源，为该过程涉及的分子机制提供了新的见解。研究结果还首次认识到 mRNA 和 miRNA 的调控作用，为叶用甘薯的改良提供了候选基因。
