Hydrogen-rich water alleviates programmed cell death induced by GA in wheat aleurone layers by modulation of reactive oxygen species metabolism

Hydrogen gas (H2) has been recently regarded as a novel gaseous signaling molecule that performs multiple functional roles in plant. Here, we demonstrate that hydrogen rich water (HRW)-an experimentally tractable reagent to assess the effects of the H2 significantly delays wheat aleurone layer programmed cell death (PCD) induced by gibberellic acid (GA). Endogenous H2 production exhibited lower level in aleurone layers under GA treatment, whereas the H2 production was apparently increased under abscisic acid (ABA) treatment. HRW not only increased H2 production but also delayed GA-induced PCD. We further observed that application of HRW substantially prevented the increases of hydrogen peroxide (H2O2) and superoxide anion radical (O2.-) triggered by GA. HRW also directly react with hydroxyl radical (·OH) to delay GA-induced PCD. Quantitative real-time PCR (qRT-PCR) and biochemical assays showed that HRW induced the transcripts and enzymatic activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) that metabolize reactive oxygen species (ROS); these increases coincided with the observed changes in O2.-, H2O2 and ·OH accumulation upon GA treatment. Our study therefore suggests that HRW-triggered alleviation of wheat aleurone layer PCD induced by GA results from a combination of H2-mediated decreases of ROS levels, including O2.-, H2O2, and ·OH.