Molecular identification of the master regulators for nicotine biosynthesis in tobacco

烟草（Nicotiana tabacum）在根中合成尼古丁和相关的吡啶类生物碱，并通过茉莉酸介导的信号级联在叶片上的草食过程中增加它们的合成。目前已鉴定出尼古丁生物合成正向调控的NIC基因座，并利用其突变等位基因培育低尼古丁烟草品种。在这里，我们研究了NIC2基因座，包括乙烯反应因子（ERF）亚家族的聚集转录因子基因；在nic2突变体中，至少有7个ERF基因被完全删除。NIC2基因座ERF与花楸中吲哚类生物碱合成的转录激活因子ORCA3是同源的，这表明NIC2/ORCA3 ERF亚家族在不同植物谱系中被独立募集来调节茉莉素诱导的次生代谢。

Tobacco (Nicotiana tabacum) synthesizes nicotine and related pyridine alkaloids in the root, and their synthesis increases upon herbivory on the leaf via a jasmonate-mediated signaling cascade. Regulatory NIC loci that positively regulate nicotine biosynthesis have been genetically identified, and their mutant alleles have been used to breed low-nicotine tobacco varieties. Here, we studied that the NIC2 locus, comprises clustered transcription factor genes of an ethylene response factor (ERF) subfamily; in the nic2 mutant, at least seven ERF genes are deleted altogether. The NIC2-locus ERFs are close homologs of ORCA3, a jasmonate-responsive transcriptional activator of indole alkaloid biosynthesis in Catharanthus roseus, indicating that the NIC2/ORCA3 ERF subfamily was recruited independently to regulate jasmonate-inducible secondary metabolism in distinct plant lineages.