HMGR regulates floral fragrance through terpene synthesis pathway in Paeonia suffruticosa

Tree peony is an aromatic plant that is rich in terpenoids. However, there are fewer studies on terpene synthesis related genes. In this study, the molecular mechanism of terpene synthesis in Paeonia suffruticosa was investigated by bulked segregant analysis sequencing (BSA-seq) and bulked segregant RNA sequencing (BSR-seq) using F 1 segregant progeny. Four genes ( HMGR1, HMGR, TPS14, BEAT ) and two genes ( TPS, HMGR ) potentially related to floral fragrance synthesis were annotated by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of BSA-seq and BSR-seq, respectively. An HMGR gene, which is closely related to terpene synthesis, was obtained by BSA-seq and BSR-seq conjoint analysis. For the first time, PsHMGR gene was cloned in Paeonia suffruticosa . The open reading frame (ORF) frame of the PsHMGR gene is 1767 bp in length and 588 amino acids were encoded. The evolution of HMGR in Cornus florida is most closely linked to the PsHMGR protein, according to phylogenetic analysis. Among the 50 terpenoids detected in the transiently transformed P. suffruticosa ‘High Noon’ by headspace solid-phase microextraction-gas chromatograph-mass spectrometer (HS-SPME-GC-MS), the most abundant terpenoids were linalool, epizonarene, and cis-calamenene, in that order. Compared to the empty vector-infected plants, the three most abundant terpenoids increased in the overexpression plants, whereas they decreased significantly in the silenced plants ( P < 0.05). Changes in the content of 32 terpenoids (12 monoterpenes and 20 sesquiterpenes), monoterpenes, sesquiterpenes, total terpenoids and HMGR enzyme activity followed the same trend. There was a substantial positive connection between the total terpenoids content and the relative expression of PsHMGR . The above results showed that PsHMGR is essential for controlling the terpene synthesis in tree peony, and laid the groundwork for the cultivation of aromatic tree peony. • Combined BSA-seq and BSR-seq analyses of F 1 progeny yielded an HMGR gene. • The HMGR gene is a key enzyme gene that was identified, described and cloned in Paeonia suffruticosa ‘Chunguihuawu’. • PsHMGR regulated 32 terpenoids including linalool, epizonarene and cis-calamenene in Paeonia suffruticosa ‘High Noon’. • PsHMGR played an important role in floral fragrance synthesis pathway in tree peony.