Salicylic acid-triggered hydrogen sulfide improves maize seed germination under drought stress by bolstering osmoregulatory system.

SA-triggered H2S signaling improves maize seed germination under drought stress by bolstering osmoregulatory system. Salicylic acid (SA) is a plant hormone, whereas hydrogen sulfide (H2S) is a novel signaling molecule, they modulate plant abiotic tolerance including drought tolerance. Their interactions, however, in maize seed germination under drought stress (DS) remains unclear. In this study, maize seeds were primed with SA, H2S, and their inhibitors alone or together, and then germinated under DS. The results showed that SA and H2S priming significantly increased germination rate of maize seeds under DS. The SA-increased germination rate was enhanced by H2S, but abolished by H2S scavenger hypotaurine (HT) and inhibitor DL-propargylglycine (PAG), indicating the cooperative effect of SA and H2S in improving seed germination under DS. Also, SA priming increased L-cysteine desulfhydrase, D-cysteine desulfhydrase, and O-acetyl-serine (thiol) lyase activities and H2S level, up-regulated ZmLCD and ZmOAS-TL expression. These effects were enhanced by H2S, but weakened by HT and PAG. However, H2S was not significant effect on SA and its metabolic enzymes in germinating seeds under DS. These data indicated that H2S functioned as a downstream signaling molecule in SA-improved maize seed germination under DS. Furthermore, SA and H2S alone or together increased ornithine aminotransferase, Δ1-pyrroline-5-carboxylate synthase, and betaine aldehyde dehydrogenase activities and proline, glycine betaine, trehalose, sucrose, and fructose levels, up-regulated ZmOAT expression. These effects were enhanced by H2S, but weakened by HT and PAG. These results implied that SA-triggered H2S signaling improved maize seed germination under DS by bolstering osmoregulatory system.