A unique sulfotransferase-involving strigolactone biosynthetic route in Sorghum

Abstract

LOW GERMINATION STIMULANT 1 (LGS1) plays an important role in strigolactones (SLs) biosynthesis and Striga resistance in sorghum but the catalytic function remains unclear. Using the recently developed SL-producing microbial consortia, we examined the activities of sorghum MAX1 analogs and LGS1. Surprisingly, SbMAX1d (accession # XP_002458367) synthesized 18-hydroxy-carlactonoic acid (18-hydroxy-CLA) directly from carlactone (CL) through four-step oxidations, and addition of LGS1 led to the synthesis of both 5-deoxystrigol (5DS) and 4-deoxyorobanchol (4DO). Further biochemical characterization found that LGS1 functions after SbMAX1d by converting 18-hydroxy-CLA to 18-sulphate-CLA to provide an easier leaving group to afford a spontaneous formation of 5DS and 4DO. The unique functions of SbMAX1 and LGS1 imply a previously unknown synthetic route towards strigolactones. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=81 SRC="FIGDIR/small/459372v1_ufig1.gif" ALT="Figure 1"> View larger version (12K): org.highwire.dtl.DTLVardef@2252eeorg.highwire.dtl.DTLVardef@172a0f8org.highwire.dtl.DTLVardef@a630e4org.highwire.dtl.DTLVardef@d3e2b6_HPS_FORMAT_FIGEXP M_FIG C_FIG