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.
Competing Interest Statement
The authors have declared no competing interest.
ABBREVIATIONS
- 5DS
- 5-deoxystrigol
- 4DO
- 4-deoxyorobanchol
- OB
- orobanchol
- SL
- Strigolactone
- CL
- carlactone
- CLA
- carlactonoic acid
- SOT or SULT
- sulfotransferase
- PAPS
- 3′-phosphoadenosine 5′-phosphosulfate
- CYP
- cytochrome P450
- MAX1
- MORE AXILLARY GROWTH 1
- LGS1
- LOW GERMINATION STIMULANT 1
- HRMS
- high-resolution mass spectrometry