Regulation Of Interaction Between Methylglyoxal And Hydrogen Sulfide Signal On Heat Tolerance In Maize Seedlings

High temperature seriously affects growth and development of plants.Maize?Zea mays?is considered as the third largest food crop after rice?Oryza sativa?and wheat?Triticum aestivum?,its yield and distribution are also affected by high temperature stress,so it is of great scientific significance to study the mechanism of heat resistance of maize.In this experiment,maize seedlings were used as materials.The following studies were conducted on the mechanism of interaction between methylglyoxal?MG?signal and hydrogen?H₂S?signal to regulate the heat tolerance of maize seedlings,and the corresponding results were obtained:Treated with 50?M MG and 500?M sodium sulfide?NaHS?alone could significantly improve the survival rate and tissue viability of maize seedlings,and reduced the content of malondialdehyde?MDA?and relative conductivity.These effects were further enhanced by NaHS+MG treatment.In addition,100?M MG scavenger N-acetylcysteine?NAC?and 100?M amino guanidine?AG?,and 100?M H₂S inhibitor propargylglycine?PAG?and 100?M scavenger hypotaurine?HT?down-regulated the MG and H₂S levels,and obtained the opposite experimental results.This suggested that there was an interaction between MG and H₂S signals in the formation of heat tolerance in maize seedlings.In the effect of MG and H₂S signal interaction on the antioxidant system,compared with the control,MG and NaHS alone treatment significantly increased ascorbate peroxidase?APX?,catalase?CAT?,glutathione reductase?GR?and peroxidase?POD?activities,as well as flavonoid and carotenoid content,reduced the rate of superoxide anion?O₂·^-?production.These effects were particularly pronounced in the NaHS combined with MG treatment.In contrast,using NAC,AG,PAG,and HT to down-regulate MG and H₂S levels,respectively,showed opposite results.This indicated that MG and H₂S signals interact to regulate the antioxidant capacity of maize seedlings.In the effect of MG and H₂S signal interaction on the osmotic regulation system,compared with the control,maize seedlings treated with MG and NaHS alone,after high temperature stress,proline?Pro?,soluble sugar,betaine?GB?and the trehalose?Tre?content was significantly increased,and this increase was particularly pronounced in the NaHS combined with MG treatment;while the above-mentioned scavengers and inhibitors were used to reduce the MG and H₂S levels,respectively,the results were reversed.This indicated that the interaction of MG and H₂S signals regulated the accumulation of osmoregulation substances,which in turn improved the heat tolerance of maize seedlings.In the effect of MG and H₂S signal interaction on the MG and H₂S metabolic system,compared with the control,MG and NaHS alone could increase the content of endogenous MG and H₂S,as well as activities and gene expression of glyoxalase I?Gly??,glyoxalase??Gly??,methylglyoxal reductase?MGR?,L-cysteine desulfhydrase?LCD?,and O-acetyl-L-serine?thiol?lyase?OAS-TL?,especially NaHS+MG is more obvious,while using scavengers and inhibitors to down-regulate MG and H₂S levels weakened these effects.Therefore,there was an interaction between MG and H₂S signals in the formation of heat tolerance in maize seedlings,and the acquisition of this heat tolerance was related to the interactions between MG and H₂S that regulated the antioxidant system,osmotic regulation system,MG detoxification system,and H₂S metabolic system of maize seedlings.