混合盐碱胁迫对藜麦种子萌发和幼苗抗氧化特性的影响

Effects of complex saline-alkali stress on seed germination and seedling antioxidant characteristics of Chenopodium quinoa

针对西北地区藜麦栽培土壤限制问题,研究盐碱胁迫对藜麦种子萌发及抗性相关酶特性的影响,探讨藜麦对盐碱土壤的适应机制,为藜麦在盐碱地的栽培实践提供理论依据。将中性盐(NaCl、Na_2SO_4)和碱性盐(NaHCO_3、NaCO_3)按不同比例混合模拟出20种混合盐碱条件对藜麦种子进行胁迫,分析盐碱胁迫下藜麦种子的发芽率、发芽势、发芽指数和抗氧化酶活性及同工酶表达。结果表明:5种盐碱胁迫均引起藜麦种子发芽率,发芽势,发芽指数降低,且随着盐浓度的增加,萌发受到显著抑制(P<0.05),对藜麦种子萌发影响较大。A,B处理组各浓度盐碱胁迫下超氧化物歧化酶(superoxide dismutase,SOD)和谷光甘肽还原酶(glutathione reductase,GR)活性均高于CK;C,D,E处理组SOD活性均低于CK,但GR活性在50mmol·L-1盐碱浓度时高于CK。过氧化物酶(peroxidase,POD)活性在盐碱浓度为50mmol·L-1时最高,随盐浓度增加POD活性比CK降低4倍,过氧化氢酶(catalase,CAT)活性随盐碱浓度的增加而下降。SDS-PAGE分析发现,盐碱胁迫可诱导SOD,POD,CAT,GR同工酶出现新的条带,但随着盐碱浓度的增加,酶带的表达量降低。上述结果说明,盐碱胁迫抑制藜麦种子萌发,其中Na_2SO_4和NaHCO_3对藜麦种子萌发抑制效应明显。本试验条件下,藜麦的耐盐碱阈值为50mmol·L-1,其中盐碱浓度是影响藜麦种子萌发的主要因素,盐组分值对藜麦种子萌发影响次之。

The saline-alkali conditions in many parts of Northern China constitute a soil factor causing significant restrictions to quinoa development.In order to better understand the adaptive physiology of quinoa under saline-alkali stress,this research focused on quinoa seed germination,antioxidant enzyme activities and isozyme characteristics.A set of 20 different alkali-saline plant stress conditions were simulated by mixing two neutral(NaCl and Na2SO4)and alkaline(NaHCO3 and Na2CO3)salts with soil in different proportions(A,NaCl∶Na 2SO 4=1∶1.B,NaCl∶Na2SO4∶NaHCO3=1∶2∶1.C,NaCl∶Na2SO4∶NaHCO3∶Na2CO3=1∶9∶9∶1.D,NaCl∶Na2SO4∶NaHCO3∶Na2CO3=1∶1∶1∶1.E,NaCl∶Na2SO4∶NaHCO3∶Na2CO3=9∶1∶1∶9)and at concentrations of(50,100,150 and 200 mmol·L^-1).Several germination and physiological indices,such as the germination percentage,germination index,germination energy were measured,and the activities of SOD,POD,CAT and GR were also analysed,and isoenzymic zymograms prepared.It was found that the five different saline-alkali stress formulations all decreased quinoa germination percentage,germination index and germination energy.With increasing saline-alkali concentration,germination was decreased dramatically(P<0.05).Compared to the control,saline-alkali stress induced higher activities of SOD and GR under treatments A and B,and lower activity of SOD under treatments C,D,and E,while GR activity was significantly increased at 50 mmol·L^-1 salt concentration.The activity of POD was the highest when the concentration of saline-alkali solution was 50 mmol·L^-1;with increased salt concentration,POD activity fell to levels 4 times lower than control,and CAT activity also decreased.SDS-PAGE revealed that saline-alkali stress induced significant changes to isomer ratios of antioxidant enzymes(SOD,POD,CAT,GR),including new isoforms.These results indicate that salt-alkaline stress inhibited seed germination of quinoa.For Na 2SO 4 and NaHCO3 on the germination inhibition of quinoa seeds was more obvious.The threshold of salt tolerance was 50 mmol·L^-1 in this study,and salt concentration was the main determinant of the degree of inhibition,with the composition of the salt solution being a minor factor.