Superoxide anion generation response to wound in Arabidopsis hypocotyl cutting

Cutting is a frequently used model to study the process of adventitious root formation, and excision of cuttings leads to rapid wound response signaling. We recently showed that as a wound signal, reactive oxygen species (ROS, mainly hydrogen peroxide) participate in adventitious root induction of hypocotyl cuttings through regulation of auxin biosynthesis and transport. Here, superoxide anion (O₂^-•), an early type of ROS, exhibited rapid burst at the cutting site immediately in response to wounding in Arabidopsis hypocotyl cuttings. Diphenylene iodonium chloride (DPI, inhibitor of NADPH oxidase) overwhelmingly suppressed O₂^-• propagation through the hypocotyl. Compared to wild type, O₂^-• burst only occur in cut base, and upward transduction were inhibited completely in NADPH oxidase mutant AtRbohD. These results indicate O₂^-• generation and propagation in response to wound and via NADPH oxidase in adventitious root induction of hypocotyl cuttings.