Biosynthesis of α-solanine and α-chaconine in potato leaves (Solanum tuberosum L.) – A 13CO2 study

Sebastian Baur, Oliver Frank, Hans Hausladen, Ralph Hückelhoven, Thomas Hofmann, Wolfgang Eisenreich, Corinna Dawid

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

α-Solanine and α-chaconine are the major glycoalkaloids (SGAs) in potatoes, but up to now the biosynthesis of these saponins is not fully understood. In planta 13CO2 labeling experiments monitored by nuclear magnetic resonance spectroscopy (NMR) and high-resolution mass spectrometry (HRMS) unraveled the SGA biosynthetic pathways from CO2 photosynthates via early precursors to the SGAs. After a pulse of ~ 700 ppm 13CO2 for four hours, followed by a chase period for seven days, specific 13C-distributions were detected in SGAs from the leaves of the labeled plant. NMR analysis determined the positional 13C-enrichments in α-solanine and α-chaconine characterized by 13C2–pairs in their aglycones. These patterns were in perfect agreement with a mevalonate-dependent biosynthesis of the isopentenyl diphosphate and dimethylallyl diphosphate precursors. The 13C-distributions also suggested cyclization of the 2,3-oxidosqualene precursor into the solanidine aglycone backbone involving a non–stereoselective hydroxylation step of the sterol a mixture of 25S-/25R-epimers of the SGAs.

Original languageEnglish
Article number130461
JournalFood Chemistry
Volume365
DOIs
StatePublished - 15 Dec 2021

Keywords

  • CO
  • Isotopologue profiling
  • Potato
  • Solanum tuberosum L.
  • Steroidal glycoalkaloids, α-solanine
  • α-Chaconine

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