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.