红砂幼苗对PEG胁迫下外源NO的生理生化响应

[Objective]Red sand(Reaumuria soongorica)belongs to the super arid small shrub,which has the characteristics of drought resistance and strong stress resistance.It is suitable for growing in arid and semi-arid areas.Due to its ability to prevent wind and fix sand,it is commonly used to maintain the stability of desert ecosystems and is of great significance for vegetation restoration.However,due to the frequent occurrence of extreme weather,the desert plant community of Red Sand faces the risk of degradation or large-scale death,so improving the drought resistance ability of Red Sand is an important measure.Exogenous nitric oxide(NO)can promote plant growth and development,and is widely used in the regulation of plant stress resistance.Polyethylene glycol(PEG)is a macromolecular polymer that can capture water and cause osmotic stress on plants.Due to the different geographical environments in which red sand grows,its response to exogenous substances may also vary under PEG stress.[Methods]Red sand seedlings in Wuwei were treated with 10%polyethylene glycol 6000(PEG 6000)and three concentrations of exogenous NO donor Sodium nitroprusside(SNP)(0.10,0.50,1.00 mmol/L),To provide theoretical basis for improving the drought resistance of red sand seedlings from different sources.[Result]1.Under PEG stress,the plant height,root length,basal diameter,fresh weight,and dry weight of red sand seedlings were significantly reduced.Exogenous NO can significantly improve the various growth indicators of red sand seedlings under PEG stress(P<0.05),especially at 0.10mmol/L,the branch height fraction of red sand increased by 45.13%and the basal diameter increased by 38.66%.After treatment with 0.50 mmol/L,the aboveground biomass of red sand increased by 52.43%,indicating that exogenous NO as a plant growth regulator can alleviate the inhibitory effect of PEG stress on the growth of red sand.SNP significantly increased the content of soluble sugar(SS),soluble protein(SP),and proline(PRO)in red sand under PEG stress at concentrations ranging from 0.10 to 1.0 mmol/L(P<0.05).Under the concentration of 0.10mmol/L SNP,the SS of red sand was 3.4 times higher than that under PEG stress alone;At a concentration of 0.10 mmol/L SNP,the SP of red sand increased by 48.42%.Exogenous NO treatment reduced the Malondialdehyde(MDA)content of red sand under PEG stress,with the largest reduction of 0.10 mmol/L SNP,79.72%;This indicates that although exogenous NO can repair membrane damage caused by drought in red sand,there are differences among different sources.SNP treatment can increase the activity of reactive oxygen species scavenging enzymes(SOD,POD,CAT)in red sand under PEG stress.3.Under PEG stress,the carbon(C),nitrogen(N),and phosphorus(P)of red sand leaves and roots exhibit different changing trends.Exogenous NO can significantly increase the C,N,and P content of red sand leaves and roots under PEG stress,with a concentration of 0.10mmol SNP having the greatest impact on the C content of red sand leaves and roots,with leaves increasing by 60.86%and roots increasing by 34.09%,respectively;The N content of red sand leaves and roots increased by 93.25 and 44.36 at 1.00 mmol/L;The P content of red sand leaves and roots increased at 0.10 mmol/L.The stoichiometry of C:N,C:P,and N:P in red sand is maximum at 0.50 mmol/L.[Conclusion]The comprehensive evaluation results indicate that the most effective concentration of exogenous NO donor SNP to alleviate PEG stress in red sand seedlings is 0.10 mmol/L.It helps to improve the growth of red sand,control its osmotic regulatory substances and membrane lipid peroxidation levels,increase the activity of antioxidant enzymes,and improve the C,N,and P levels of red sand leaves and roots.