Figure 3.

Strigolactones biosynthesis pathway. The conversion of all-trans-β-carotene into carlactone is successively catalyzed by the cis/trans-β-carotene isomerase D27 that reversibly converts all-trans-β-carotene into 9-cis-β-carotene, which is subsequently cleaved by CCD7 into 9-cis-β-apo-10′-carotenal and β-ionone. The next enzyme, CCD8, transforms 9-cis-β-apo-10′-carotenal into carlactone and ω-OH-(4-CH3) heptanal. Carlactone is then oxidized, catalyzed by CYP711 enzymes [Arabidopsis MAX1, rice carlactone oxidase (CO), and orobanchol synthase (OS)] into carlactonoic acid and other SLs. After methylation, carlactonoic acid is oxidized by the oxidoreductase LBO into yet unidentified product. See text for abbreviations. Created with ‘Biorender’.