cis-Cinnamic Acid Is a Novel, Natural Auxin Efflux Inhibitor That Promotes Lateral Root Formation

作者：Ward Steenackers, Petr Klíma, Mussa Quareshy, Igor Cesarino, Robert P. Kumpf, Sander Corneillie, Pedro Araújo, Tom Viaene, Geert Goeminne, Moritz K. Nowack, Karin Ljung, Jiřı́ Friml, Joshua J. Blakeslee, Ondřej Novák, Eva Zažı́malová, Richard Napier, Wout Boerjan, Bartel Vanholme · 发表于：PLANT PHYSIOLOGY · 年份：2016 · DOI：10.1104/pp.16.00943 · 被引用次数：85 · 研究领域：Plant Molecular Biology Research、Light effects on plants、Plant tissue culture and regeneration

Auxin steers numerous physiological processes in plants, making the tight control of its endogenous levels and spatiotemporal distribution a necessity. This regulation is achieved by different mechanisms, including auxin biosynthesis, metabolic conversions, degradation, and transport. Here, we introduce cis-cinnamic acid (c-CA) as a novel and unique addition to a small group of endogenous molecules affecting in planta auxin concentrations. c-CA is the photo-isomerization product of the phenylpropanoid pathway intermediate trans-CA (t-CA). When grown on c-CA-containing medium, an evolutionary diverse set of plant species were shown to exhibit phenotypes characteristic for high auxin levels, including inhibition of primary root growth, induction of root hairs, and promotion of adventitious and lateral rooting. By molecular docking and receptor binding assays, we showed that c-CA itself is neither an auxin nor an anti-auxin, and auxin profiling data revealed that c-CA does not significantly interfere with auxin biosynthesis. Single cell-based auxin accumulation assays showed that c-CA, and not t-CA, is a potent inhibitor of auxin efflux. Auxin signaling reporters detected changes in spatiotemporal distribution of the auxin response along the root of c-CA-treated plants, and long-distance auxin transport assays showed no inhibition of rootward auxin transport. Overall, these results suggest that the phenotypes of c-CA-treated plants are the consequence of a local change in auxin ...