Full-Length Transcript Sequencing and Comparative Transcriptomic Analysis of Paeonia lactiflora Reveals Tissue- and Ecotype-Specific Expression of Paeoniflorin Biosynthesis-Related Genes.

Paeonia lactiflora Pall., a Paeoniaceae family member, is a herbaceous perennial flower of significant horticultural importance. It holds prominence in traditional Chinese medicine due to its therapeutic applications in pain relief, inflammation reduction, and immune disorder treatment. Paeoniflorin, the active monoterpene compound in P. lactiflora, exhibits diverse biological activities, such as anti-inflammatory and immune-regulatory effects. Although the pharmacological effects of paeoniflorin have been extensively studied, its biosynthetic pathway remains elusive. Here, we combined PacBio Iso-Seq and RNA-seq techniques to investigate three distinct tissues from two different P. lactiflora ecotypes with varying paeoniflorin contents. The primary objective was to identify candidate genes involved in the biosynthesis of paeoniflorin and related monoterpenes. Differentially expressed unigenes encoding cytochrome P450s, UDP-glucoronosyl and UDP-glucosyl transferases, and transcription factors, which might be associated with monoterpene diversity in P. lactiflora, were identified. In addition, we analyzed genetic differentiation between the two P. lactiflora ecotypes. Notably, gene expression in the terpene pathway within root and rhizome tissues was downregulated compared to leaf tissues. This intriguing observation led us to speculate that paeoniflorin synthesis primarily occurs in the leaves and is subsequently transported to the roots. However, further experimentation is required to provide substantial evidence and verify this hypothesis. [ABSTRACT FROM AUTHOR]