Identification of Key Genes Involved in Sesquiterpene Synthesis in Nardostachys jatamansi Based on Transcriptome and Component Analysis

<b>Background:</b><i>Nardostachys jatamansi</i> (D. Don) DC. (<i>N. jatamansi</i>.) is an endangered medicinal plant native to the Himalayas that is widely used in traditional medicine due to its terpenoid compounds, especially sesquiterpenes, which are abundant in <i>N. jatamansi</i>. However, the mechanism of sesquiterpene metabolism remains unclear. <b>Methods:</b> Transcriptome sequencing analyses of different parts (roots and rhizomes, leaves, anthocaulus and flowers) and developmental stages (rejuvenation, budding, flowering, fruiting and withering) of cultivated <i>N. jatamansi</i> were conducted using the Illumina platform. Key genes involved in regulating the sesquiterpene metabolism pathway in <i>N. jatamansi</i> were identified by combining component analyses of various tissues and developmental stages. Furthermore, these key genes were validated through MeJA treatment and a chemical composition analysis. <b>Results:</b> A transcriptome sequencing analysis was performed on 24 samples from four tissues and in five developmental stages, yielding 183.18 Gb of clean data with a Q30 base percentage of 92% or above. A total of 269,136 UniGenes were obtained and annotated. Genes related to sesquiterpene synthesis were screened and validated by RT-qPCR using annotation results from various databases. Twelve candidate genes involved in sesquiterpene synthase were identified. Following MeJA treatment, an RT-qPCR analysis revealed that the expression of the <i>NjTPS-49, NjTPS-54, NjTPS-56, NjTPS-57</i> and <i>NjTPS-59</i> genes was positively regulated. Additionally, an HPLC analysis indicated an increase in the nardosinone content after MeJA treatment. This study demonstrates that <i>NjTPS-49, NjTPS-54, NjTPS-56, NjTPS-57</i> and <i>NjTPS-59</i> are potential candidate genes for sesquiterpene synthesis. <b>Conclusion:</b> The obtained findings establish the groundwork for elucidating the mechanism of sesquiterpene synthesis in <i>N. jatamansi</i> and contribute to the conservation of <i>N. jatamansi</i> resources.