H2O2 participates induction and formation of potato tubers by activating tuberization-related signal transduction pathways

Abstract Reactive oxygen species (ROS, especially hydrogen peroxide, H2O2) act as signaling molecules to mediate growth, development and stress response of plants. However, whether and how H2O2 is involved in induction and formation of potato tubers is little known. The present study showed that there was an obvious accumulation of ROS (including H2O2, O2·- and total ROS) during tuber induction and formation in stolons/tubers, especially in the hook-like subapical part of stolons prior to tuberization detected by staining observation and quantitative measurement. Furthermore, exogenous H2O2 treatment significantly enhanced percentage of tuber formation. By contrast, addition of either the ROS inhibitor diphenyleneiodonium chloride (DPI) or H2O2 scavenger catalase (CAT) resulted in a decline of tuber formation. In addition, expression analysis of 9 key tuberization-related genes demonstrated that the H2O2-induced tuberization could be associated with H2O2-controlled regulation of these tuberization- and signaling pathway-related genes, especially SELF-PRUNING 6A gene (StSP6A), which was dramatically up-regulated during early stage of tuber induction and H2O2 treatment. When StSP6A was knocked out by CRISPR-Cas9-mediated genome editing, the tuberization frequency of StSP6A null-mutants became extremely lower under H2O2 treatments. These findings indicate that H2O2 accumulation in stolons might plays an important role acting as a signaling molecule to initiate tuber induction, H2O2-induced tuber formation is triggered by regulating the tuberization-related gene expression and activating signal transduction pathways, and StSP6A is a pivotal player in the H2O2-induced tuber formation in potato.