CYP722C from cotton, a homolog of the enzyme involved in orobanchol synthesis in cowpea and tomato, catalyzes the conversion of carlactonoic acid to 5-deoxystrigol. Strigolactones (SLs) are important phytohormones with roles in the regulation of plant growth and development. These compounds also function as signaling molecules in the rhizosphere by interacting with beneficial arbuscular mycorrhizal fungi and harmful root parasitic plants. Canonical SLs, such as 5-deoxystrigol (5DS), consist of a tricyclic lactone ring (ABC-ring) connected to a methylbutenolide (D-ring). Although it is known that 5DS biosynthesis begins with carlactonoic acid (CLA) derived from β-carotene, the enzyme that catalyzes the conversion of CLA remains elusive. Recently, we identified cytochrome P450 (CYP) CYP722C as the enzyme that catalyzes direct conversion of CLA to orobanchol in cowpea and tomato (Wakabayashi et al., Sci Adv 5:eaax9067, 2019). Orobanchol has a different C-ring configuration from that of 5DS. The present study aimed to characterize the homologous gene, designated GaCYP722C, from cotton (Gossypium arboreum) to examine whether this gene is involved in 5DS biosynthesis. Expression of GaCYP722C was upregulated under phosphate starvation, which is an SL-producing condition. Recombinant GaCYP722C was expressed in a baculovirus-insect cell expression system and was found to catalyze the conversion of CLA to 5DS but not to 4-deoxyorobanchol. These results strongly suggest that GaCYP722C from cotton is a 5DS synthase and that CYP722C is the crucial CYP subfamily involved in the generation of canonical SLs, irrespective of the different C-ring configurations.

中文翻译：

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来自 Gossypium arboreum 的 CYP722C 催化 carlactonic acid 转化为 5-deoxystrigol

来自棉花的 CYP722C 是一种参与豇豆和番茄中奥罗班酚合成的酶的同源物，可催化将 carlactonoic acid 转化为 5-deoxystrigol。独脚金内酯（SLs）是重要的植物激素，在植物生长发育的调节中发挥作用。这些化合物还通过与有益的丛枝菌根真菌和有害的根部寄生植物相互作用，在根际起到信号分子的作用。典型的 SLs，例如 5-deoxystrigol (5DS)，由连接到甲基丁烯内酯 (D-ring) 的三环内酯环 (ABC-ring) 组成。虽然已知 5DS 的生物合成始于源自 β-胡萝卜素的卡拉内酯酸 (CLA)，但催化 CLA 转化的酶仍然难以捉摸。最近，我们将细胞色素 P450 (CYP) CYP722C 鉴定为在豇豆和番茄中催化 CLA 直接转化为 orobanchol 的酶（Wakabayashi 等人，Sci Adv 5:eaax9067, 2019）。Orobanchol 具有与 5DS 不同的 C 环配置。本研究旨在表征来自棉花（Gossypium arboreum）的同源基因GaCYP722C，以检查该基因是否参与5DS生物合成。GaCYP722C 的表达在磷酸盐饥饿下上调，这是一种产生 SL 的条件。重组 GaCYP722C 在杆状病毒昆虫细胞表达系统中表达，并被发现催化 CLA 转化为 5DS，但不催化转化为 4-脱氧奥班胆。