Integrative Analysis of the steroidal alkaloids distribution and biosynthesis of Fritillaria cirrhosa and Fritillaria thunbergii through Metabolome and Transcriptome Analyses

<em>Fritillaria cirrhosa is high-altitude endangered medicinal and edible homologous plant with antitussive and anti-inflammatory activities as it contains a variety of active ingredients, especially steroidal alkaloids. Therefore, understanding the distribution of steroidal alkaloids in F.cirrhosa to elucidate their synthesis pathway is essential for sustainable bioengineering production. Here, non-target metabolomics and transcriptome of F.cirrhosa and Fritillaria thunbergii were performed to identify the genes responsible for steroidal alkaloids synthesis. Metabolomics data showed that 1288 metabolites were identified in F. cirrhosa and Fritillaria thunbergii, of which steroidal alkaloids were most abundant alkaloids, including peimine, peimisine, peiminine, jervine, tomatidine, solanine, solasonine, solamargine, solasodine, and veratramine as well as newly found edpetiline and khasianine. The majority of steroidal alkaloids (solamargine, jervine, solanine, solasonine, solasodine, edpetiline, khasianine, veratramine and tomatidine) content in F. cirrhosa were significantly highly than those in Fritillaria thunbergii, while the content of peimine and peimisine are lower than in Fritillaria thunbergii. Moreover, the contents of these compounds were the highest in Fritillaria delavayi (SS). Additionally, differential gene expression analysis indicated that genes associated with MEP pathway and MVA pathway regulating 5C intermediate (IPP &amp; DMAPP) biosynthesis in F. cirrhosa and Fritillaria thunbergii, respectively. (we firstly found that genes associated with the MVA pathway regulated steroidal alkaloids biosynthesis in Fritillaria thunbergia, as the genes related this pathway highly expressed in Fritillaria thunbergia.). Furthermore, the structural genes (CYP90B1, CYP734A6, CYP94N2, CYP90A4, GAME12 and GAME17) and transcription factor (3AP2, 3MYB, 2C2H2, 1NAC, 1bHLH and 1C3H) associated with steroidal alkaloids biosynthesis were identified based on their high expression in F. cirrhosa.</em>