Hydrogen peroxide might be a downstream signal molecule of hydrogen sulfide in seed germination of mung bean (Vigna radiata)

Hydrogen sulfide (H2S) and hydrogen peroxide (H2O2) are both plant cell signal molecules, which play a vital role in seed germination. However, signal crosstalk between H2S and H2O2 in seed germination is not completely clear. In this study, H2S and H2O2 interactions in the germination of mung bean seeds was investigated. The results showed that H2S and H2O2 treatment alone promoted the germination of mung bean seeds, while pretreatment with H2O2 scavenger dimethythiourea (DTMU), NADPH oxidase (NOX) inhibitor diphenylene iodonium chloride (DPI) and free radical scavenger tiron eliminated H2S-promoted seed germination, respectively, but pretreatment of seeds with inhibitor of H2S biosynthesis DL-propargylglycine (PAG) and H2S scavenger hydroxylamine (HT) prior to H2O2 did not weaken H2O2-promoted seed germination. In addition, NaHS treatment increased the contents of endogenous H2S and H2O2 in germinating seeds, and H2O2 accumulation lagged behind H2S, indicating that H2S promoted seed germination in the upstream of H2O2 in mung bean seeds. Also, pretreatment of seeds with H2S and H2O2 alone significantly stimulated the increase of protease activity and accumulation of total free amino acids (Aa) in cotyledons as well as the growth of mung bean sprouts, whereas stimulative effects of H2S were removed by supplement of DTMU, DPI and tiron, but pretreatment with PAG and HT did not eliminate seed germination promoted by H2O2 compared with the control without H2O2 treatment. These results suggested that H2S and H2O2 could promote the germination of mung bean seeds by mobilizing reserve protein, and H2O2 may be a downstream signal molecule of H2S.