Abstract
Strigolactone are plant secondary metabolites which function as host recognition signals for arbuscular mycorrhizal fungi and root parasitic plants, Striga and Orobanche. Recently, strigolactones have been identified as a novel class of plant hormones inhibiting shoots branching. In this study, characterization of strigolactones in cucumber (Cucumis sativus L.) root exudate was conducted. Cucumber was found to produce at least 9 germination stimulants including orobanchol, orobanchyl acetate, 7-oxoorobanchyl acetate, and 7-oxoorobanchol. In addition to these, two novel strigolactones were isolated and their structures were determined as 7α-hydroxy-orobanchyl acetate and 7β-hydroxy-orobanchyl acetate by 1D and 2D NMR spectroscopy, CD, and ESI- and EI-MS spectrometries.
