Abstract
Background
The continued emergence of side-effects caused by synthetic drugs underscores the need for plant-based drugs in human medicine. Medicinal rhizomatous crops are a “goldmine for modern drugs”, and include such species as Gloriosa superba L. and Colchicum autumnale L., the producers of colchicine, a plant-based medicine. The natural isomer of bioactive colchicine is used to effectively treat major diseases such as cancer, cardiovascular disease, and gout. The medicinal properties of colchicine are well characterized, however, almost nothing is known about its biosynthesis. The paucity of information on the colchicine biosynthetic pathway is a significant barrier to biomanufacturing of this biomedicine. A comparative transcriptome study of G. superba and C. autumnale serves as a sequence resource to aid with identification of this biomedicine pathway and rhizome development genes for synthetic biotechnology toolbox, which will enable improved colchicine biomanufacturing.
Result
Transcriptomes of two colchicine synthesizing monocots G. superba and C. autumnale were interrogated to identify putative cDNAs encoding enzymes and transcription factors involved in the colchicine biosynthetic pathway and rhizome development. Mining of the transcriptomes using Blast2GO led to the identification from G. superba and C. autumnale, respectively, of 20 and 29 candidate colchicine biosynthetic genes N-methyltransferases, 3-O-methyltransferases, cytochrome P450s, a class that could catalyze several steps in the pathway, and N-acetyltransferases. Similarly, 19 and 15 candidate rhizome developmental genes, which belongs to several classes including GIGANTEA, CONSTANS, Phytochrome B, Sucrose Synthase), Flowering Locus T, and REVOLUTA. Likewise, about 16 and 12 transcription factors involved in regulating rhizome development and secondary metabolic pathways in rhizomes such as MADS-box, AP2-EREBP, bHLH, MYB, NAC, and WRKY were also found in G. superba and C. autumnale, respectively.
Conclusion
The predicted genes in G. superba and C. autumnale encode colchicine pathway enzymes that provide fundamental information for plant-based biomedicine engineering in biorhizomes and microorganisms, a potentially important area of synthetic biotechnology. Additionally, increasing our understanding of rhizome functional genomics will lead to improved colchicine biomanufacturing, and generate important knowledge that can be applied to many other medicinal plant species, allowing for the engineered production of additional biomedicines in medicinal rhizomes.
About polemohoral populations of Colchicum autumnale
