title: Confirming stereochemical structures of strigolactones produced by rice and tobacco.
abstract: Major strigolactones (SLs) produced by rice (Oryza sativa L. cv. Nipponbare) and tobacco (Nicotiana tabacum L. cv. Michinoku No. 1) were purified and their stereochemical structures were determined by comparing with optically pure synthetic standards for their NMR and CD data and retention times and mass fragmentations in ESI-LC/MS and GC-MS. SLs purified from root exudates of rice plants were orobanchol, orobanchyl acetate, and ent-2'-epi-5-deoxystrigol. In addition to these SLs, 7-oxoorobanchyl acetate and the putative three methoxy-5-deoxystrigol isomers were detected by LC-MS/MS. The production of 7-oxoorobanchyl acetate seemed to occur in the early growth stage, as it was detected only in the root exudates collected during the first week of incubation. The root exudates of tobacco contained at least 11 SLs, including solanacol, solanacyl acetate, orobanchol, ent-2'-epi-orobanchol, orobanchyl acetate, ent-2'-epi-orobanchyl acetate, 5-deoxystrigol, ent-2'-epi-5-deoxystrigol, and three isomers of putative didehydro-orobanchol whose structures remain to be clarified. Furthermore, two sorgolactone isomers but not sorgolactone were detected as minor SLs by LC-MS/MS analysis. It is intriguing to note that rice plants produced only orobanchol-type SLs, derived from ent-2'-epi-5-deoxystrigol, but both orobanchol-type and strigol-type SLs, derived from 5-deoxystrigol were detected in tobacco plants.
authors.affiliation: Weed Science Center, Utsunomiya University, 350 Mine-machi, Utsunomiya 321-8505,  Japan.
authors.forename: Xiaonan
authors.initials: X
authors.lastname: Xie
authors.forename: Kaori
authors.initials: K
authors.lastname: Yoneyama
authors.forename: Takaya
authors.initials: T
authors.lastname: Kisugi
authors.forename: Kenichi
authors.initials: K
authors.lastname: Uchida
authors.forename: Seisuke
authors.initials: S
authors.lastname: Ito
authors.forename: Kohki
authors.initials: K
authors.lastname: Akiyama
authors.forename: Hideo
authors.initials: H
authors.lastname: Hayashi
authors.forename: Takao
authors.initials: T
authors.lastname: Yokota
authors.forename: Takahito
authors.initials: T
authors.lastname: Nomura
authors.forename: Koichi
authors.initials: K
authors.lastname: Yoneyama
mesh_terms: D002853:Chromatography, Liquid; D007783:Lactones / Q000737:chemistry* / Q000378:metabolism; D013058:Mass Spectrometry; D012275:Oryza / Q000378:metabolism*; D053147:Plant Exudates / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D015203:Reproducibility of Results; D013237:Stereoisomerism; D014026:Nicotiana / Q000378:metabolism*
chemical_list: C528323:5-deoxystrigol; D007783:Lactones; D053147:Plant Exudates; C472678:orobanchol