Identification of candidate genes related to calanolide biosynthesis by transcriptome sequencing of Calophyllum brasiliense (Calophyllaceae).

BACKGROUND: Calophyllum brasiliense is highlighted as an important resource of calanolides, which are dipyranocoumarins that inhibit the reverse transcriptase of human immunodeficiency virus type 1 (HIV-1 RT). Despite having great medicinal importance, enzymes involved in calanolide, biosynthesis and the pathway itself, are still largely unknown. Additionally, no genomic resources exist for this plant species. RESULTS: In this work, we first analyzed the transcriptome of C. brasiliense leaves, stem, and roots using a RNA-seq strategy, which provided a dataset for functional gene mining. According to the structures of the calanolides, putative biosynthetic pathways were proposed. Finally, candidate unigenes in the transcriptome dataset, potentially involved in umbelliferone and calanolide (angular pyranocoumarin) biosynthetic pathways, were screened using mainly homology-based BLAST and phylogenetic analyses. CONCLUSIONS: The unigene dataset that was generated in this study provides an important resource for further molecular studies of C. brasiliense, especially for functional analysis of candidate genes involved in the biosynthetic pathways of linear and angular pyranocoumarins.