Evolution of interorganismal strigolactone biosynthesis in seed plants.

Zhou, Anqi; Kane, Annalise; Wu, Sheng; Wang, Kaibiao; Santiago, Michell; Ishiguro, Yui; Yoneyama, Kaori; Palayam, Malathy et al. · Science · 2025

basic_science · Level V

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Abstract

Strigolactones (SLs) are methylbutenolide molecules derived from β-carotene through an intermediate carlactonoic acid (CLA). Canonical SLs act as signals to microbes and plants, whereas noncanonical SLs are primarily plant hormones. The cytochrome P450 CYP722C catalyzes a critical step, converting CLA to canonical SLs in most angiosperms. Using synthetic biology, we investigated the function of <i>CYP722A</i>, an evolutionary predecessor of <i>CYP722C</i>. CYP722A converts CLA into 16-hydroxy-CLA (16-OH-CLA), a noncanonical SL detected exclusively in the shoots of various flowering plants. 16-OH-CLA application restores control of shoot branching to SL-deficient mutants in <i>Arabidopsis thaliana</i> and is perceived by the SL signaling pathway. We hypothesize that biosynthesis of 16-OH-CLA by CYP722A was a metabolic stepping stone in the evolution of canonical SLs that mediate rhizospheric signaling in many flowering plants.

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