Wound-induced signals regulate root organogenesis in Arabidopsis explants

Abstract

BackgroundReactive oxygen species (ROS) and calcium ions (Ca2+) are representative signals of plant wound responses. Wounding triggers cell fate transition in detached plant tissues and induces de novo root organogenesis. While the hormonal regulation of root organogenesis has been widely studied, the role of early wound signals including ROS and Ca2+ remains largely unknown.ResultsWe identified that ROS and Ca2+ are required for de novo root organogenesis, but have different functions in Arabidopsis explants. The inhibition of the ROS and Ca2+ signals delayed root development in detached leaves. Examination of the auxin signaling pathways indicated that ROS and Ca2+ did not affect auxin biosynthesis and transport in explants. Additionally, the expression of key genes related to auxin signals during root organogenesis was not significantly affected by the inhibition of ROS and Ca2+ signals. The addition of auxin partially restored the suppression of root development by the ROS inhibitor; however, auxin supplementation did not affect root organogenesis in Ca2+-depleted explants.ConclusionsOur results indicate that, while both ROS and Ca2+ are key molecules, at least in part of the auxin signals acts downstream of ROS signaling, and Ca2+ acts downstream of auxin during de novo root organogenesis in leaf explants.