a Nara Institute of Science and Technology , Graduate School of Biological Sciences , Takayama , Ikoma , Nara , Japan.
b Philip Morris International R&D , Philip Morris Products , Neuchâtel , Switzerland.
Plant Signal Behav. 2017 Jun 3;12(6):e1338225. doi: 10.1080/15592324.2017.1338225. Epub 2017 Jun 14.
In tobacco, the defense alkaloid nicotine is produced in roots and accumulates mainly in leaves. Signaling mediated by jasmonates (JAs) induces the formation of nicotine via a series of structural genes that constitute a regulon and are coordinated by JA-responsive transcription factors of the ethylene response factor (ERF) family. Early steps in the pyrrolidine and pyridine biosynthesis pathways likely arose through duplication of the polyamine and nicotinamide adenine dinucleotide (NAD) biosynthetic pathways, respectively, followed by recruitment of duplicated primary metabolic genes into the nicotine biosynthesis regulon. Transcriptional regulation of nicotine biosynthesis by ERF and cooperatively-acting MYC2 transcription factors is implied by the frequency of cognate cis-regulatory elements for these factors in the promoter regions of the downstream structural genes. Indeed, a mutant tobacco with low nicotine content was found to have a large chromosomal deletion in a cluster of closely related ERF genes at the nicotine-controlling NICOTINE2 (NIC2) locus.
在烟草中，防御生物碱尼古丁在根部产生，主要在叶片中积累。茉莉酸（JAs）介导的信号通过一系列构成调控子的结构基因诱导尼古丁的形成，这些基因受乙烯反应因子（ERF）家族的 JA 反应转录因子协调。吡咯烷和吡啶生物合成途径的早期步骤可能分别通过多胺和烟酰胺腺嘌呤二核苷酸（NAD）生物合成途径的重复产生，然后将重复的初级代谢基因招募到尼古丁生物合成调控子中。ERF 和协同作用的 MYC2 转录因子对尼古丁生物合成的转录调控暗示了这些因子在下游结构基因启动子区域的同源顺式调控元件的频率。事实上，发现一种尼古丁含量低的突变烟草在尼古丁调控基因 NICOTINE2（NIC2）位点的一个紧密相关的 ERF 基因簇中发生了一个大的染色体缺失。
