干旱及盐胁迫对黄芩种子萌发和黄酮合成关键酶活性的影响

Effects of Drought and Salt Stress on Seed Germination and Key Enzymes Activities of Flavonoid Synthesis in Scutellaria baicalensis

目的:研究干旱及盐胁迫模拟条件下黄芩种子萌发及黄酮合成关键酶活性,解析黄芩种子萌发生长的抗性能力及黄酮合成路径关键酶活性的变化。方法:测定不同浓度聚乙二醇(PEG-6000)与盐(NaCl)胁迫下黄芩种子的发芽势、发芽率、相对发芽率、发芽指数、活力指数及幼苗的苗高、根长、鲜重,并对苯丙氨酸解氨酶(PAL)、肉桂酸4-羟化酶(C4H)、4-香豆酰-CoA连接酶(4CL)、查耳酮合成酶(CHS)、黄酮合成酶(FNS)5个黄芩黄酮合成关键酶活性进行测定。结果:5%PEG-6000溶液干旱胁迫浓度对黄芩种子萌发影响较小,当PEG-6000浓度>5%、NaCl浓度>50 mmol/L时,各萌发指标呈降低趋势,对黄芩种子萌发生长抑制作用明显增强。黄酮合成关键酶活性整体呈现先升高后降低的趋势,但升降幅度存在差异。结论:黄芩具有一定的抗旱耐盐能力,PEG-6000>5%、NaCl>50 mmol/L的胁迫浓度对黄芩种子萌发生长具有抑制作用,适度干旱及盐胁迫能提高黄酮合成关键酶活性。

Objective:To study the seed germination and key enzyme activity of flavonoids synthesis in Scutellaria baicalensis under drought and salt stress,to analyze the changes of resistance to germination and growth of Scutellaria baicalensis seeds and the key enzyme activity of flavonoids synthesis pathway.Methods:The germination potential,germination rate,relative germination rate,germination index,vigor index of Scutellaria baicalensis seeds and seedling height,root length,fresh weight of seedling under different concentrations of PEG-6000 and NaCl stress were measured.The activities of five key enzymes of flavone synthesis in Scutellaria baicalensis were determined,including phenylalnine ammonialyase(PAL),cinnamate 4-hydroxylase(C4 H),4-coumaryl-CoA ligase(4 CL),chaleone synthase(CHS)and flavone synthase(FNS).Results:The drought stress concentration of 5%PEG-6000 solution had little effect on the germination of Scutellaria baicalensis seeds.When PEG-6000 concentration>5%and NaCl concentration>50 mmol/L,all germination indicators showed a decreasing trend,and the inhibition on seed germination and growth of Scutellaria baicalensis was significantly enhanced.The activity of key enzymes of flavonoid synthesis increased first and then decreased,but the amplitude of increase and decrease was different.Conclusion:Scutellaria baicalensis has a certain ability of drought resistance and salt tolerance.The stress concentration of PEG-6000>5%and NaCl>50 mmol/L can inhibit the germination and growth of Scutellaria baicalensis seeds.Moderate drought and salt stress can improve the activity of key enzymes for flavonoids synthesis.