Abstract

Rhynchophylline (RIN) and isorhynchophylline (IRN), two of the representative types of indole alkaloids, showed the unique spiroindole structures produced inUncaria rhynchophylla. As the bioactive constituent ofU. rhynchophylla, IRN has recently drawn extensive attention toward antihypertensive and neuroprotective activities. Despite their medicinal importance and unique chemical structure, the biosynthetic pathways of plant spiroindole alkaloids are still largely unknown. In this study, we usedU. rhynchophylla, extensively used in traditional Chinese medicine (TCM), a widely cultivated plant of theUncariagenus, to investigate the biosynthetic genes and characterize the functional enzymes in the spiroindole alkaloids. We aim to use the transcriptome platform to analyse the tissue-specific gene expression in spiroindole alkaloids-producing tissues, including root, bud, stem bark and leaf. The critical genes involved in the biosynthesis of precursors and scaffold formation of spiroindole alkaloids were discovered and characterized. The datasets from this work provide an essential resource for further investigating metabolic pathways inU. rhynchophyllaand facilitate novel functional enzyme characterization and a good biopharming approach to spiroindole alkaloids.Keywords:Uncaria rhynchophylla;spiroindole alkaloids;biosynthetic pathway;transcriptome;rhynchophylline and isorhynchophylline