Contents of paeoniflorin and albiflorin in two Korean landraces of Paeonia lactiflora and characterization of paeoniflorin biosynthesis genes in peony.

Background and research purpose: Paeoniflorin and albiflorin are monoterpene glycosides that exhibit various medicinal properties in Paeonia species. This study explored the terpene biosynthesis pathway and analyzed the distribution of these compounds in different tissues of two Korean landraces of Paeonia lactiflora to gain insights into the biosynthesis of monoterpene glycosides in P. lactiflora and their potential applications.

Materials and methods: Two Korean landraces, Hongcheon var. and Hwacheon var, of P. lactiflora were used for the analyses. Contents of the paeoniflorin and albiflorin were analyzed using HPLC. RNA was extracted, sequenced, and subjected to transcriptome analysis. Differential gene expression, KEGG, and GO analyses were performed. Paeoniflorin biosynthesis genes were isolated from the transcriptomes using the genes in Euphorbia maculata with the NBLAST program. Phylogenetic analysis of of 1-Deoxy-D-xylulose 5-phosphate synthase (DOXPS), geranyl pyrophosphate synthase (GPPS), and pinene synthase (PS) was carried out with ClustalW and MEGA v5.0.

Results and discussion: Analysis of paeoniflorin and albiflorin content in different tissues of the two P. lactiflora landraces revealed significant variation. Transcriptome analysis yielded 36,602 unigenes, most of which were involved in metabolic processes. The DEG analysis revealed tissue-specific expression patterns with correlations between landraces. The isolation of biosynthetic genes identified 173 candidates. Phylogenetic analysis of the key enzymes in these pathways provides insights into their evolutionary relationships. The sequencing and analysis of DOXPS, GPPS, PS revealed distinct clades and subclades, highlighting their evolutionary divergence and functional conservation. Our findings highlight the roots as the primary sites of paeoniflorin and albiflorin accumulation in P. lactiflora, underscoring the importance of tissue-specific gene expression in their biosynthesis.

Conclusion: this study advances our understanding of monoterpene glycoside production and distribution in Paeonia, thereby guiding further plant biochemistry investigations.