| Seeds as special reproductive organ of the seed plants such as maize,which play a very important role in the life of seed plants.Seeds with high vitality can rapidly germinate in normal field cultivation,thus forming robust and neat seedlings.Therefor,the normal germination of seeds is a guarantee for increasing crop yield.With global warming,high temperatures have become one of the major environmental stresses that limit crop yields.Hydrogen sulfide（H2S）is the third gaseous signal molecule following carbon monoxide（CO）and nitric oxide（NO）,which has been confirmed to participate in a variety of physiological and biochemical processes in plants.In this paper,using maize seeds as experimental materials,the effect of H2S signal on seed germination under high temperature environment and the relationship to osmotic adjustment substances and antioxidant system were studied,obtaining the following conclusions:Soaking seeds with different concentrations of exogenous H2S,the germination rate,radicle length and plumule length of germinating maize seed during high temperature stress,indicating that H2S signal can improve the germination of maize seeds under high temperature stress.Using exogenous H2S soaked maize seeds,and germinated for 96 h under high temperature stress,it showed that the contents of osmotic adjustment substances such as proline（Pro）,glycine betaine（GB）and trehalose（Tre）in the radicles and plumules of germinating maize seeds were increased,the determination of the relevant metabolic enzyme activity associated with osmotic adjustment substances also confirmed this phenomenon.Using exogenous Pro,GB and Tre soaked maize seeds respectively,after high temperature stress,it showed that the germination rate,root length,and shoot length of the germinated maize seeds were all increased,and the synthetic inhibitors of Pro,GB,and Tre were applied exogenously gabculine（Gab）and disulfiram（Dis）and sodium pyrophosphate dibasic（Spd）inhibited these effects,suggesting that H2S signaling involved in the improvement of maize seed germination under high temperature stress by the role of osmotic adjustment substance.High-temperature treatment had different degrees of promotion to superoxide dismutase（SOD）,glutathione reductase（GR）,glutathione peroxidase（GPX）,and ascorbate peroxidase（APX）activity in radicles and plumules during the germination of maize seeds,application of exogenous H2S can further increase the activity of these enzymes.This indicates that exogenous H2S can increase the activity of antioxidant enzymes in germinating maize seeds under high temperature stress.Similarly,exogenous H2S treatment could increase the content of antioxidants such as ascorbic acid（AsA）and glutathione（GSH）in radicles and plumules of germinating maize seeds,and increase the germination of maize seed AsA and dehydroascorbic acid（DHA）ratio.The results showed that H2S signaling involved in the improvement of maize seed germination under high temperature stress by the role of antioxidant systems.In summary,H2S signal could improve the germination of corn seeds under high temperature stress,and the important role of osmotic adjustment substances and antioxidant systems in this improvement. |
