外源MeJA对镉胁迫下波斯菊生长及抗氧化系统的影响

Effect of Exogenous Methyl Jasmonate on Growth and Antioxidant System of Coreopsis under Cadmium Stress

以波斯菊种子和幼苗为试验材料,采用滤纸上发芽和叶面喷施盆栽幼苗的方法,探讨不同浓度(0、0.5、1.0、5.0、10.0和25.0μmol·L^-1)茉莉酸甲酯(MeJA)对镉(100μmol·L^-1 Cd^2+)胁迫下波斯菊种子萌发、幼苗生长以及抗氧化系统的影响。结果表明,镉胁迫条件下,波斯菊的生长受到严重抑制,施加低浓度MeJA(1.0~5.0μmol·L^-1)可以促进波斯菊种子萌发,增加波斯菊幼苗叶绿素含量,促进叶片干物质含量的积累和叶片相对含水量增加,提高叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)的活性,增加氧化型谷胱甘肽(GSH)含量和氧化型谷胱甘肽/还原型谷胱甘肽(GSH/GSSG)比值,降低游离脯氨酸(Pro)和丙二醛(MDA)含量;而高浓度的MeJA(大于10μmol·L^-1)则表现出相反的抑制作用,影响镉胁迫下波斯菊种子萌发和幼苗的相关代谢。研究发现,适宜浓度的外源MeJA,在镉胁迫条件下可通过降低渗透调节物质的含量,诱导增强抗氧化酶活性,增加氧化型谷胱甘肽(GSH)含量,调整GSH/GSSG比例等途径促进波斯菊种子萌发和幼苗的生长,有效缓解镉胁迫对波斯菊的伤害,从而提高波斯菊幼苗的耐镉性能。

In this study,the effects of methyl jasmonate(MeJA)with various concentrations(0,0.5,1.0,5.0,10.0,25.0μmol·L^-1)on seed germination and seedling growth and antioxidant system of coreopsis has been explored.Seeds were germinated on filter paper bedding and leaf spray of potted seedlings.The results showed that the growth of coreopsis was severely inhibited when the cadmium ion concentration is 100μmol·L^-1.The application of MeJA(1.0-5.0μmol·L^-1)promoted the germination and increase the chlorophyll content of coreopsis seedlings,promoted leaf dry matter accumulation and increased relative leaf water content,increased the activities of antioxidase,increased the contents of oxidized glutathione and the rate of oxidized glutathione/reduced glutathione values,reduced the contents of malondialdehyde and proline.The low concentration of MeJA could effectively alleviate the damage of cadmium stress.However,high concentration of MeJA(above 10μmol·L^-1)exhibited inhibitory effects on the metabolism of coreopsis seedlings.Overall,appropriate concentration of exogenous MeJA could promote the growth and cadmium tolerance of coreopsis,through decreasing osmotic adjustment substance contents,enhancing antioxidant enzyme activities,increasing GSH content and adjusting GSH/GSSG ratio.