Evolution of interorganismal strigolactone biosynthesis in seed plants
Anqi Zhou, Annalise Kane, Sheng Wu, Kaibiao Wang, Michell Santiago, Yui Ishiguro, Kaori Yoneyama, Malathy Palayam, Nitzan Shabek, Xiaonan Xie, David C. Nelson, Yanran Li
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 CYP722A , an evolutionary predecessor of CYP722C . 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 Arabidopsis thaliana 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.