Transcriptomic profiling of Gloriosa superba for the discovery of colchicine biosynthesis
Gloriosa superba produces colchicine, an alkaloid that binds microtubules and is utilized as an anti-inflammatory pharmaceutical. Despite the historical use of colchicine in medicine, no biosynthetic genes had previously been identified for the production of this molecule. Colchicine accumulates to differential levels in various Gloriosa superba tissue types, suggesting that comparative transcriptomic analyses of these tissues could guide discovery of putative biosynthetic genes. We have performed RNA sequencing of four different tissues (leaf, stem, root, and rhizome) from Gloriosa superba. By leveraging this transcriptomic data set with metabolomic data and chemical logic, we have elucidated a near complete biosynthetic pathway to colchicine and have illuminated the processes by which plant synthesize the complex carbon scaffold of this alkaloid class.