外源5-氨基乙酰丙酸对盐胁迫下紫苏种子萌发及幼苗抗氧化酶活性的影响

目的 通过对紫苏种子萌发及幼苗生理特性的研究，寻找提高紫苏种子及幼苗在盐胁迫下抗性能力的途径。方法 测定盐胁迫下紫苏种子在不同浓度的外源5-氨基乙酰丙酸（ALA）处理后，发芽势、发芽率、发芽指数和活力指数的变化，并对紫苏幼苗叶片的相对含水量、幼苗总生物量、可溶性糖量、叶片丙二醛（MDA）量以及超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性进行测定。结果 100 mmol/L NaCl胁迫下的紫苏种子萌发受到显著抑制，但是经过不同质量浓度的ALA处理后，各项萌发指标均有所升高，其中经过50 mg/L ALA处理后效果最为显著，各项指标均达到最大值，发芽势为71.3%，发芽率为90.5%，发芽指数为15.9，活力指数为0.129 6。各处理均提高了幼苗总生物量和可溶性糖的量，减缓了盐胁迫下紫苏叶片相对含水量下降的趋势，降低了叶片MDA的量，显著地提高了SOD、POD和CAT 3种酶的活性，且经过50 mg/L ALA处理后3种酶的活性分别达到最大值（0.79、7.69、5.84 U/mg）。结论 50 mg/L ALA能够有效地减缓盐胁迫对紫苏种子及幼苗产生的伤害，提高种子及幼苗的抗盐能力。

Effect of exogenous 5-aminolevulinic acid on seed germination and antioxidase activities of Perilla frutescens seedlings under NaCl stress

Objective In order to get the method of improving the salt resistance of seeds and seedlings for Perilla frutescens under NaCl stress, seed germination and physiological characteristics of P. frutescens seedlings were studied. Methods Several physiological indexes of P. frutescens seeds treated by 5-aminolevulinic acid (5-ALA) were measured. And other indexes of the seedlings like relative water content (RWC), the biomass, the content of soluble sugar, and malondialdehyde (MDA), the activities of superoxide (SOD), peroxidase (POD), and catalase (CAT) were also measured. Results The germination indexes of P. frutescens seeds under NaCl stress have a obvious inhibition. But after the treatment at different concentrations of 5-ALA every germination index were all increased. And the seeds treated by 5-ALA with the concentration of 50 mg/L have the most significantly increase in every index. The germination vigor was 71.3%, the germination rate was 90.5%, the germination index and vigor index were 15.9 and 0.129 6, respectively. Every treatment of them coule improve the biomass and soluble sugar of the seedlings; The RWC of P. frutescens leaves decreased under NaCl stress, but after treated by 5-ALA, the rate of decrease has been relieved and the content of MDA in leaves was decreased. The activities of three enzymes including SOD, POD, and CAT were all increased. And the treatment of 5-ALA with the concentration of 50 mg/L got the maximin with 0.79, 7.69, and 5.84 U/mg, respectively. Conclusion 5-ALA with the appropriate concentration of 50 mg/L could significantly alleviate the damages to the seeds and seedlings of P. frutescens under NaCl stress and promote the salt resistance of the seeds and seedlings.