Abstract
Strigolactones (SLs) function in the rhizosphere as host detection signals for both symbionts arbuscular mycorrhizal (AM) fungi and root parasitic plants, and in the plants they act as a class of plant hormones inhibiting shoot branching. In this study, characterization of SLs produced by rice (Oryza sativa L. cv. Nipponbare) was conducted by comparing retention times of germination stimulants on reversed phase HPLC with those of synthetic standards and by LC-MS/MS. In the roots exudates collected from rice plants grown hydroponically, known SLs including 7-oxoorobanchyl acetate, 2'-epiorobanchol, orobanchol, orobanchyl acetate, and 2'-epi-5-deoxystrigol were detected. An unknown peak was detected in the channel for 7-oxoorobanchol (m/z 383>286) with distinct germination stimulation on Orobanche minor and Striga hermonthica seeds. LC-MS/MS and GC/MS analyses indicated that this is a novel SL. Purification and structural elucidation of the novel SL will be presented.
