Combined metabolome and transcriptome to analyze the regulatory network of key enzymes in the synthesis of Senkirkine in Emilia sonchifolia

Emilia sonchifolia (L.) DC. is a commonly used medicinal and edible plant in the folk, and its toxic component of Senkirkine (Sek) has hepatotoxicity, which can lead to sinusoidal obstruction syndrome if exposed in large amounts, and will cause hepatic megaloblastosis and hepatic fibrosis if ingested in small amounts over a long period of time. This study was based on the metabolomics of Emilia sonchifolia , which analysed and identified the alkaloid constituents of 4 parts of Emilia sonchifolia , namely, the root, stem, leaf and flower. A total of 91 differential metabolites were detected, belonging to 10 alkaloids, among which pyrrolizidine alkaloids accounted for 13%. The relative content of Senkirkine differed most significantly between the group of root and flower comparison, and the relative content of Senkirkine in root was significantly higher than in flower. A total of 119,886 unigenes and 32,797 differentially expressed genes were identified in the transcriptome data, and the 45 key enzymes of the biological synthesis pathway of Senkirkine were selected, which belonged to 7 categories. There are a total of 172 candidate enzyme genes in it, of which methyltransferase, alcohol dehydrogenase, acyltransferase, and cyclooxygenase genes were significantly more expressed in roots than in flowers, and the metabolome and transcriptome expression patterns were basically the same. The 5 key enzyme gene sequences of the biological synthesis pathway of Senkirkine were selected for qRT-PCR. The results showed that, using flowers as the control group, 4 key enzyme genes ( BAHD-Ats , CCoAOMT , BOMT , 3AT ) were all highest in roots, while the relative expression of CAD was highest in stems, which was basically consistent with the transcriptome pattern. This study provided a reference for the functional expression analysis of the genes of Emilia sonchifolia , and laid a foundation for the future analysis of the Senkirkine synthesis pathway and the regulation of the key enzyme genes of the toxic components, so as to obtain the low-toxic raw materials of Emilia sonchifolia .