Comprehensive transcriptome analysis suggested that the primary metabolism is modulated to augment the supply of substrates towards secondary metabolism operating in the glandular trichomes of Nicotiana tabacum. The comparative gene expression and co-expression network analysis revealed that certain members of transcription factor genes belonging to the MYB, HD-ZIP, ERF, TCP, SRS, WRKY and DOF families may be involved in the regulation of metabolism and/other aspects in the glandular trichomes of N. tabacum The glandular trichomes of Nicotiana tabacum are highly productive in terms of secondary metabolites and therefore have been projected to be used as a prognostic platform for metabolic engineering of valuable natural products. For obvious reasons, detailed studies pertaining to the metabolic and gene regulatory networks operating in the glandular trichomes of N. tabacum are of pivotal significance to be undertaken. We have carried out next-generation sequencing of glandular trichomes of N. tabcaum and investigated differential gene expression among different tissues, including trichome-free leaves. We identified a total of 37,269 and 37,371 genes, expressing in trichome free leaf and glandular trichomes, respectively, at a cutoff of FPKM ≥ 1. The analysis revealed that different pathways involved with the primary metabolism are modulated in glandular trichomes of N. tabacum, providing a plausible explanation for the enhanced biosynthesis of secondary metabolism in the glandular trichomes. Further, comparative gene expression analysis revealed several genes, which display preferential expression in the glandular trichomes and thereby seem to be potential candidate genes for future studies in connection to the discovery of novel trichome specific promoters. The present study also led to the comprehensive identification of 1750 transcription factor genes expressing at a cutoff of FPKM ≥ 1 in the glandular trichomes of N. tabacum. The clustering and co-expression analysis suggested that transcription factor genes belonging to HD-ZIP, ERF, WRKY, MYB, TCP, SRS and DOF families may be the major players in the regulation of gene expression in the glandular trichomes of N. tabacum. To the best of our knowledge, the present work is the first effort towards detailed identification of genes, especially regulatory genes expressing in the glandular trichomes of N. tabacum. The data resource and the empirical findings from present work in all probability must, therefore, provide a reference and background context for future work aiming at deciphering molecular mechanism of regulation of secondary metabolism and gene expression in the glandular trichomes of N. tabacum.

中文翻译：

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全面的转录组分析提供了对烟草毛状体中代谢和基因调控网络的深入了解。

综合转录组分析表明，初级代谢被调节以增加对在烟草腺毛中进行的次级代谢的底物供应。比较基因表达和共表达网络分析表明，属于 MYB、HD-ZIP、ERF、TCP、SRS、WRKY 和 DOF 家族的转录因子基因的某些成员可能参与调控代谢和/其他方面。普通烟草的腺毛 烟草的腺毛在次生代谢物方面具有很高的生产力，因此预计将用作有价值的天然产物代谢工程的预后平台。由于显而易见的原因，有关在烟草腺毛中运作的代谢和基因调控网络的详细研究具有关键意义。我们对烟草腺毛进行了新一代测序，并研究了不同组织之间的差异基因表达，包括无毛叶。我们确定了总共 37,269 和 37,371 个基因，分别在无毛叶和腺毛中表达，截止 FPKM ≥ 1。分析表明，与初级代谢有关的不同途径在普通烟草的腺毛中受到调节，为腺毛中次生代谢的生物合成增强提供了一个合理的解释。此外，比较基因表达分析揭示了几个基因，它们在腺毛中表现出优先表达，因此似乎是未来研究与发现新的毛状体特异性启动子相关的潜在候选基因。本研究还导致在烟草腺毛中以 FPKM ≥ 1 的截止值表达的 1750 个转录因子基因的全面鉴定。聚类和共表达分析表明，属于 HD-ZIP、ERF、WRKY、MYB、TCP、SRS 和 DOF 家族的转录因子基因可能是烟草腺毛中基因表达调控的主要参与者。据我们所知，目前的工作是详细鉴定基因的第一次努力，特别是在普通烟草腺毛中表达的调节基因。