The bioconversion of 5-deoxystrigol to sorgomol by the sorghum, Sorghum bicolor (L.) Moench

• Published in: Phytochemistry (Oxford) 2013-09, Vol.93, p.41-48
• Main Authors: Motonami, Noriko, Ueno, Kotomi, Nakashima, Hitomi, Nomura, Saki, Mizutani, Masaharu, Takikawa, Hirosato, Sugimoto, Yukihiro
• Format: Article
• Language: English
• Subjects: 5-Deoxystrigol; Bioconversion; biotransformation; Chromatography, Liquid; cultivars; cytochrome P-450; hydroxylation; Lactones - chemistry; Lactones - metabolism; Mass Spectrometry; Molecular Structure; plant hormones; Plant Roots - chemistry; Plant Roots - metabolism; Poaceae; rhizosphere; roots; shoots; Sorghum; Sorghum - chemistry; Sorghum - metabolism; Sorghum bicolor; Sorgomol; Stereoisomerism; stereoisomers; Strigolactone
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2013.02.017

5-Deoxystrigol and its ent-2′-epimer were absorbed by sorghum roots, converted to sorgomol and ent-2′-epi-sorgomol, respectively, and exuded out of the roots. The conversion involves cytochrome P450. [Display omitted] ► The bioconversion of 5-deoxystrigol (5-DS) in sorghum (Sorghum bicolor) to sorgomol was established. ► The LC–MS/MS analyses established conversion of 5-DS and ent-2′-epi-5-DS to sorgomol and ent-2′-epi-sorgomol, respectively. ► The conversion is most likely catalyzed by a cytochrome P450. Strigolactones, important rhizosphere signalling molecules and a class of phytohormones that control shoot architecture, are apocarotenoids of plant origin. They have a structural core consisting of a tricyclic lactone connected to a butyrolactone group via an enol ether bridge. Deuterium-labelled 5-deoxystrigol stereoisomers were administered to aquacultures of a high sorgomol-producing sorghum cultivar, Sorghum bicolor (L.) Moench, and conversion of these substrates to sorgomol stereoisomers was investigated. Liquid chromatography–mass spectrometry analyses established that 5-deoxystrigol (5-DS) and ent-2′-epi-5-deoxystrigol were absorbed by sorghum roots, converted to sorgomol and ent-2′-epi-sorgomol, respectively, and exuded out of the roots. The conversion was inhibited by uniconazole-P, implying the involvement of cytochrome P450 in the hydroxylation. These results provide experimental evidence for the postulated biogenetic scheme for formation of strigolactones, in which hydroxylation at C-9 of 5-DS can generate sorgomol.