シトクロムP450が関与する典型的ストリゴラクトン生合成に関する研究

抄録

In the canonical strigolactone (SL) biosynthesis, the ring-closing reaction of carlactonoic acid (CLA) and subsequent modification of the A- and B-ring are thought to generate structurally diverse SLs. It was found that VuCYP722C and SlCYP722C in cowpea and tomato, respectively, are involved in the direct conversion of CLA to orobanchol without passing through 4-deoxyorobanchol. Knocking out this gene in tomato resulted in no detection of canonical SLs in root exudates, whereas the knockout plants did not show the branching phenotypes, suggesting that an active hormone that inhibits shoot branching is derived from non-canonical SLs. The study also revealed that GaCYP722C of cotton catalyzes the conversion of CLA to 5-deoxystrigol (5DS). Therefore, members of CYP722C subfamily, which is widely conserved in dicot plants, are key enzymes involved in the canonical SL biosynthesis. Additionally, the enzymes responsible for the structural diversification of canonical SLs in sorghum were investigated, and SbCYP728B35 was identified as sorgomol synthase that introduces a hydroxy group at C-9 of 5DS. These results indicate that cytochrome P450 is deeply involved in the canonical SL biosynthesis and reveal a part of the structural diversification mechanism in SL biosynthesis.