Mandrakes (Mandragora spp., Solanaceae) are known to contain tropane alkaloids and have been used since antiquity in traditional medicine. Tropane alkaloids such as scopolamine and hyoscyamine are used in modern medicine to treat pain, motion sickness, as eye pupil dilators and antidotes against organo-phosphate poisoning. Hyoscyamine is converted to 6β-hydroxyhyoscyamine (anisodamine) and scopolamine by hyoscyamine 6β-hydroxylase (H6H), a 2-oxoglutarate dependent dioxygenase. We describe here a marked chemo-diversity in the tropane alkaloid content in Mandragora spp. M. officinarum and M. turcomanica lack anisodamine and scopolamine but display up to 10 fold higher hyoscyamine levels as compared with M. autumnalis. Transcriptomic analyses revealed that H6H is highly conserved among scopolamine-producing Solanaceae. MoH6H present in M. officinarum differs in several amino acid residues including a homozygotic mutation in the substrate binding region of the protein and its prevalence among accessions was confirmed by Cleaved-Amplified-Polymorphic-Sequence analyses. Functional expression revealed that MaH6H, a gene isolated from M. autumnalis encodes an active H6H enzyme while the MoH6H sequence isolated from M. officinarum was functionally inactive. A single G to T mutation in nucleotide 663 of MoH6H is associated with the lack of anisodamine and scopolamine in M. officinalis.
Bibliographical noteFunding Information:
The research leading to these results has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement n° 613513. We thank Prof. Shimon Ben Shabat, BGU University and Dr. Yaakov Tadmor, Newe Yaar Center for helpful discussions and teaching the CAPS methodologies. We also thank Galil Tzuri for helping with the Sanger sequencing.
© 2019 Elsevier B.V.
- 2-Oxoglutarate-dependent dioxygenases
- Cleaved-amplified-polymorphic-sequence (CAPS) analyses
- Tropane alkaloids
ASJC Scopus subject areas
- Agronomy and Crop Science
- Plant Science