In Solanaceae plants, the major phytoalexins produced during the induction of plant defense are sesquiterpenoids, such as capsidiol for Nicotiana species and rishitin for Solanum species, which are produced via the mevalonate (MVA) pathway. Eight enzymes are involved in the production of farnesyl pyrophosphate (FPP), the common precursor of phytosterols for maintaining membrane integrity and sesquiterpenoid phytoalexins for plant defense. In this study, expression profiles of N. benthamiana genes for the production of capsidiol during the induction of disease resistance were investigated. In the genome of N. benthamiana, multiple copies of genes for each enzyme in the MVA pathway were identified, and the expression of some, but not all MVA genes, was significantly upregulated after inoculation with Phytophthora infestans, or treatment with the INF1 elicitor, a secretory protein of P. infestans. For genes encoding enzymes involved in capsidiol production, 10 copies of 5-epi-aristolochene synthase (NbEAS) and six copies of 5-epi-aristolochene dihydroxylase (NbEAH) were identified, and all copies were significantly upregulated during the induction of disease resistance. Gene silencing of MAP kinase genes NbWIPK, NbSIPK, and NbNTF4 compromised INF1-induced production of phytoalexins. Expression analysis of control and NbWIPK/SIPK/NTF4-silenced plants indicated that most of the MVA genes are not under the control of these MAP kinases. In contrast, the expression pattern of NbWIPK/SIPK/NTF4 and all copies of NbEAH genes showed significant correlation, suggesting that MAP kinases are critical regulators of transcriptional upregulation of specific genes for capsidiol production.

中文翻译：

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烟草中产辣椒素中涉及的酶基因的表达谱

在茄科植物中，诱导植物防御过程中产生的主要植物抗毒素是倍半萜类，例如通过甲羟戊酸（MVA）途径产生的用于烟草属物种的辣椒素和用于茄属植物的rishitin 。八种酶参与了法呢基焦磷酸酯（FPP）的生产，FPP是用于维持膜完整性的植物甾醇的常见前体，以及用于植物防御的倍半萜类植物抗毒素。在这项研究中，调查了本氏烟草基因在诱导抗病性过程中产生辣椒素的表达谱。在本氏烟草的基因组中，鉴定了MVA途径中每种酶的基因的多个副本，在接种疫霉疫霉菌或感染致病疫霉的分泌蛋白INF1激发子后，某些（而非全部）MVA基因的表达明显上调。。对于编码参与辣椒素生产的酶的基因，已鉴定出10个拷贝的5-表位-茴香醚合酶（NbEAS）和6个拷贝的5个表位-茴香醚二羟化酶（NbEAH），并且在诱导抗病性时所有拷贝均显着上调。MAP激酶基因NbWIPK，NbSIPK和NbNTF4的基因沉默破坏了INF1诱导的植物抗毒素的产生。对照和NbWIPK / SIPK / NTF4沉默的植物的表达分析表明，大多数MVA基因不受这些MAP激酶的控制。与此相反，表达模式NbWIPK / SIPK / NTF4和的所有副本NbEAH基因显示显著相关性，这表明MAP激酶对于生产capsidiol特定基因的转录上调的关键调节剂。