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标题：Transcriptome Sequencing and Metabolism Analysis Reveals the role of Cyanidin Metabolism in Dark-red Onion (Allium cepa L.) Bulbs
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作者：Chunsha Zhang ; Xiaojie Li ; Zongxiang Zhan 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2018
卷号：8
期号：1
页码：14109
DOI：10.1038/s41598-018-32472-5
语种：English
出版社：Springer Nature
摘要：Onion ( Allium cepa L.) is an important bulbous vegetable crop that possesses important properties related to health as well as extraordinary colors. Naturally white onion bulbs were used in this study to reveal the complex metabolic mechanisms that underlie phenotypic traits, especially bulb pigmentation. Six libraries (three dark-red and three white) were constructed and analyzed to elucidate differences in cyanidin (Cy) metabolism between dark-red and white onion bulbs. Libraries were screened using RNA-sequencing (RNA-seq) to reveal the differentially expressed genes (DEGs) involved in anthocyanin biosynthesis at the transcriptional level. Comparison with the Kyoto Encyclopedia of Genes and Genomes (KEGG) database shows that a total of 27 unigenes participate in onion anthocyanin biosynthesis and 16 DEGs perform critical roles in flavonoid biosynthesis. Expression patterns of color-related flavonoid compounds associated with the onion anthocyanin biosynthesis pathway (ABP) show that flavonoid 3′,5′-hydroxylase (F3′5′H) and dihydroflavonol 4-reductase (DFR) genes play crucial roles in the biosynthesis of dark-red bulbs, the expression levels of flavonol synthase (FLS) and DFR genes may act to block blue pigmentation, and the loss of Cy from white onion bulbs might explain multibranching in the synthesis of this compound. Positive variation in the F3′5′H/F3′H ratio also affects onion bulb color diversity. The transcriptome presented here provides a basis for future onion molecular breeding based on variations in the diversity of ornamental plant pigmentation.