Hydrogen Sulfide Enhances Alfalfa(Medicago Sativa) Tolerance Against Salinity During Seed Germination And Its Relationship With Nitric Oxide

Hydrogen sulfide (H2S), same as nitric oxide (NO), carbon oxide (CO), is one of gaseous cellular messenger molecules, it plays an important role in relaxing vascular and gastrointestinal smooth muscle, and regulating neuronal excitability, learning, and memory. The molecular mechanisms and signal transduction pathways of hydrogen sulfide in plant biology are still unclear. Here, by using pharmacological and biochemical approaches, we report that H2S promotes alfalfa seeds germination and alleviates salinity damage.Upon100mM NaCl treatment, both H2S donor sodium hydrosulfide (NaHS) and NO donor sodium nitroprusside (SNP) at100μM could significantly attenuate the inhibition of alfalfa (Medicago sativa) seed germination and thereafter seedling growth inhibition. Meanwhile, the ratio of potassium (K) to sodium (Na) in the root parts was increased. Total, isozymatic activities or corresponding transcripts of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (POD), or ascorbate peroxidase (APX) were activated differentially, thus resulting in the alleviation of oxidative damage. While the addition of the specific scavenger of NO2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt(cPTIO)reversed above effects. Therefore, the above protective roles of NaHS might be related to the induction of endogenous NO. Meanwhile, NaHS-triggered NO production was confirmed.Together, our observations indicate that H2S enhances plant responses against salinity stress by reducing oxidative damage, which might have a possible interaction with NO.