Analysis of floral differences in terpenoids between two genotypes of Jerusalem artichoke (Helianthus tuberosus L.) by HS-SPME-GC/MS-based on the metabolome and transcriptome

Jerusalem artichoke (Helianthus tuberosus L.) bears flowers with bright colors and diverse fragrances. It can be used for greening, and brewing flower tea, and has great ornamental and edible values. However, little is known about the floral components and genetic differences in their biosynthetic processes. In this study, we detected the floral components of two Jerusalem artichoke flowers having different fragrances by headspace solid-phase microextraction gas chromatography/mass spectrometry (HS-SPME-GC/MS), along with the analysis of related pathways of differential metabolites, differential expression genes (DEGs) and terpenoid biosynthesis. The results showed that 201 metabolites, primarily monoterpenoids and sesquiterpenoids, were detected in JA192 and JA399. Among them, most terpenoids were found in metabolites and their relative contents of JA399 were significantly higher than those of JA192. Safranal and rimuene were unique components of JA399. The combined transcriptomic and metabolomic analyses showed that among the JA192 and JA399, gcpE1, gcpE2, IDI1, and IDI2 genes were the key genes in the biosynthetic pathway of (+)-α-pinene, (-)-β-pinene and safranal. DXS1 gene played an important role in the biosynthetic pathway of rimuene. IDI1, IDI2, HMGR3, and HMGS1 genes played positive roles in the biosynthetic pathway of β-copaene and (+)-δ-cadinene. In summary, differences in terpenoids and their contents were the major factors responsible for the differences in floral components between the two genotypes of Jerusalem artichoke. These were associated with DEGs related to terpenoid synthesis.