外源5-氨基乙酰丙酸对干旱胁迫下甘草种子萌发及幼苗生理特性的影响

以药用植物甘草种子和幼苗为材料,在20%PEG-6000模拟干旱胁迫条件下,测定了不同浓度外源5-氨基乙酰丙酸(ALA)处理甘草种子的发芽势(Gv)、发芽率(Gr)、发芽指数(Gi)和活力指数(Vi)的变化,以及ALA处理幼苗叶片的质膜透性、丙二醛(MDA)含量、可溶性糖含量、游离脯氨酸含量和超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性。结果显示:(1)在20%PEG-6000胁迫下,甘草种子萌发受到显著抑制,而各项萌发指标经过不同浓度的ALA进行恢复处理后均有明显提高,且均以10 mg.L-1ALA处理的各项指标值最大,其种子发芽势(75%)、发芽率(91%)比干旱胁迫对照显著提高了35%和30%,发芽指数(36.2)和活力指数(709.7)分别提高至干旱胁迫的2.6和3.5倍。(2)各ALA处理较对照均显著提高了干旱胁迫下甘草幼苗总生物量、可溶性糖的含量及脯氨酸含量,却显著降低了甘草叶片的MDA含量和质膜透性,同时显著提高了干旱胁迫下甘草叶片中的SOD、POD和CAT的活性,且以10 mg.L-1ALA处理后的酶活性最强。研究表明,适宜浓度(10 mg.L-1)的ALA能显著提高干旱胁迫下甘草种子的萌发能力,通过调节渗透调节物质含量和保护酶活性来有效减缓干旱胁迫对甘草幼苗的伤害,提高甘草种子及幼苗的抗旱能力。

Effect of Exogenous ALA on Seed Germination and Physiological Characteristics of Glycyrrhiza uralensis Seedlings under Drought Stress

In order to get the method of improve the drought resistance of seeds and seedlings for Glycyrrhiza uralensis under drought stress,we studied seed germination and physiological characteristics of G.uralensis seedlings.Several physiological indexes of G.uralensis seeds were measured treated by 5-aminolevulinic acid(ALA) under drough stress like the germination vigor,germination rate,germination index and vigor index.And other indexes of the seedlings like the membrance permeability,the contents of malondialdehyde(MDA),soluble sugar and proline,the activities of superoxide(SOD),peroxidase(POD) and catalase(CAT) were also measured.The result shows:(1)the germination indexes of G.uralensis seeds under drought stress have a obvious inhibition.But after the treatment of different concentrations of ALA,every germination indexes were all increased.And the seeds that treated by ALA with the concentration of 10 mg·L-1 has the most significantly increase.The germination vigor and the germination rate was 75% and 91%,respectively,compared with the drought stress,it improve 35% and 30%,respectively.The germination indexes and vigor index were 36.2 and 709.7,respectively.It is 2.6 and 3.5 times to the drought sress.(2)Every treatments were all improved the biomass of the seedlings,the contents of soluble sugar(37.20 mg·g-1) and proline(28.79 μg·g-1) increased significantly compared to the drought stress.But after treated by ALA,the content of MDA(10.42 μmol·g-1) decreased under drought stress and the rate of decrease has been relieved.The membrance permeability was also decreased to 8.44%.The activities of three enzymes include SOD,POD and CAT were all increased.And the treatment of ALA with the concentration of 10 mg·L-1 get the maximin with 882.84 U·g-1·h-1,27.63 U·mg-1·min-1 and 3.45 U·mg-1·min-1,respectively.These result show that ALA with the appropriate concentration of 10 mg·L-1 could significantly alleviate the damages to the seeds and seedlings of G.uralensis under drought stress and promote the drought resistance of the seeds and seedlings.