Yamada Yasuyuki, Shimada Tomoe, Motomura Yukiya, Sato Fumihiko
Department of Plant Gene and Totipotency, Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan.
PLoS One. 2017 Oct 27;12(10):e0186953. doi: 10.1371/journal.pone.0186953. eCollection 2017.
Transcription factors control many processes in plants and have high potentials to manipulate specialized metabolic pathways. Transcriptional regulation of the biosynthesis of monoterpenoid indole alkaloids (MIAs), nicotine alkaloids, and benzylisoquinoline alkaloids (BIAs) has been characterized using Catharanthus roseus, Nicotiana and Coptis plants. However, metabolic engineering in which specific transcription factors are used in alkaloid biosynthesis is limited. In this study, we characterized the effects of ectopic expression of CjWRKY1, which is a transcriptional activator with many targets in BIA biosynthesis in Coptis japonica (Ranunculaceae) and Eschscholzia californica (California poppy, Papaveraceae). Heterologous expression of CjWRKY1 in cultured California poppy cells induced increases in transcripts of several genes encoding BIA biosynthetic enzymes. Metabolite analyses indicated that the overexpression of the CjWRKY1 gene also induced increases in the accumulation of BIAs such as sanguinarine, chelerythrine, chelirubine, protopine, allocryptopine, and 10-hydroxychelerythrine in the culture medium. Previous characterization of EcbHLH1 and current results indicated that both transcription factors, WRKY1 and bHLH1, are substantially involved in the regulation of BIA biosynthesis. We discuss the function of CjWRKY1 in E. californica cells and its potential for metabolic engineering in BIA biosynthesis.
转录因子控制植物中的许多过程，并且在操纵特殊代谢途径方面具有很高的潜力。利用长春花、烟草和黄连属植物，已对单萜吲哚生物碱（MIAs）、烟碱生物碱和苄基异喹啉生物碱（BIAs）生物合成的转录调控进行了表征。然而，在生物碱生物合成中使用特定转录因子的代谢工程是有限的。在本研究中，我们表征了CjWRKY1异位表达的影响，CjWRKY1是一种转录激活因子，在毛茛科的日本黄连和罂粟科的加州罂粟的BIA生物合成中有许多靶标。CjWRKY1在培养的加州罂粟细胞中的异源表达导致几个编码BIA生物合成酶的基因转录本增加。代谢物分析表明，CjWRKY1基因的过表达还导致培养基中诸如血根碱、白屈菜红碱、白屈菜玉红碱、原阿片碱、别隐品碱和10-羟基白屈菜红碱等BIA积累增加。先前对EcbHLH1的表征和当前结果表明，WRKY1和bHLH1这两种转录因子都大量参与了BIA生物合成的调控。我们讨论了CjWRKY1在加州罂粟细胞中的功能及其在BIA生物合成中的代谢工程潜力。
