Bioconversion of 5-deoxystrigol stereoisomers to monohydroxylated strigolactones by plants

Abstract

The bioconversion of 5-deoxystrigol (5DS) and 4-deoxyorobanchol (4DO), the simplest canonical strigolactones (SLs), into monohydroxylated SLs such as strigol, sorgomol and orobanchol was confirmed by administering of stable isotope-labeled substrates to hydroponically grown plants. Liquid chromatography-mass spectrometry analyses established that 5DS was stereoselectively converted into strigol and sorgomol by cotton (<i>Gossypium hirsutum</i>) and Chinese milk vetch (<i>Astragalus sinicus</i>), respectively. 4DO was converted into orobanchol by rice (<i>Oryza sativa</i>). However, the red bell pepper (<i>Capsicum annuum</i>), red clover (<i>Trifolium pratense</i>), and pea (<i>Pisum sativum</i>) negligibly converted 4DO into orobanchol. The red bell pepper converted <i>ent</i>-4DO into 2',8-bis<i>epi</i>-sorgomol. These results suggest that some plants generate orobanchol without passing through 4DO.