2,4-EBL对不同浓度镉胁迫下龙葵(Solanum nigrum L.)幼苗的缓解作用

Alleviation Effects of 2,4-EBL on Seedlings of Solanum nigrum L.under Different Concentrations of Cadmium Stress

为探究外源2,4-表油菜素内酯(2,4-Epicastasterone,2,4-EBL/EBL)对镉(Cd)胁迫下龙葵幼苗的影响作用。本研究以Cd超积累植物龙葵为试验材料,采用水培法,对龙葵幼苗进行不同浓度的Cd胁迫处理(0,300μmol/L,600μmol/L,1 200μmol/L)后,对其叶片喷施浓度为10^-5mol/L的EBL溶液,研究外源EBL对Cd胁迫下龙葵幼苗生长的影响,以及过氧化物酶(peroxidase,POD)、过氧化氢酶(catalase,CAT)与超氧化物歧化酶(superoxide dismutase,SOD)的活性变化,丙二醛(malondialdehyde,MDA)和可溶性糖含量及叶绿素荧光动力学参数的变化。结果表明:(1)单一Cd胁迫下,龙葵幼苗株高、鲜重、干重及SOD、POD活性呈现低促高抑趋势,随着Cd浓度的增加,抑制根的伸长,增加了MDA含量、可溶性糖含量及CAT活性,降低了PSⅡ潜在荧光活性Fv/Fo和初始光化学效率Fv/Fm。(2)EBL降低了不同浓度Cd胁迫后MDA含量,提高了根部可溶性糖含量和抗氧化酶活性及叶片PSⅡ反应中心功能。研究发现外源EBL有利于龙葵幼苗在重金属Cd胁迫下提高其抗氧化酶活性,维持膜质氧化程度、光能的捕获与转换能力,促进龙葵幼苗的生长,有效缓解Cd胁迫对龙葵幼苗生长的抑制作用,且600μmol/L Cd胁迫后喷施EBL后期(12~24 h)对龙葵幼苗缓解效果最佳。本研究为外源施用EBL提高植物耐重金属Cd能力提供理论依据。

In this research,the cadmium hyperaccumulator plant Solanum nigrum L.by using hydroponics was used as the experiental material to explore the effect of exogenous 2,4-EBL on cadmium(Cd)stress,and the seedings were sprayed with 2,4-EBL with a con-centration of 10^-5 mol/L after treated with different concentrations of Cd stress(0,300μmol/L,600μmol/L,1 200μmol/L).It was detected that the effects of exogenous EBL on the growth of Solanum nigrum L.seedlings under Cd stress,activities of peroxidase(POD),catalase(CAT)and superoxide dismutase(SOD),contents of malondialdehyde(MDA)and soluble sugar,and changes of chlorophyll fluorescencekinetic parameters.The results showed that:(1)Plant height,fresh weight,dry weight,activities of SOD and POD of Solanum nigrum L.seedlings showed"low-promotion,high-inhibition"trend with single Cd stress,with the increase of Cd concentration,it inhibited root elongation,increased content of MDA,soluble sugar and activity of CAT,reduced Fv/Foand Fv/Fm.(2)EBL decreased MDA content of Solanum nigrum L.after different concentrations Cd stress,increased content of soluble sugar in root,activity antioxidant enzyme,and the central function of PSⅡreaction in leaves.The research found that,exogenous EBL was beneficial to the antioxidant activity of Solanum nigrum L.seedlings under Cd stress,maintenance of the degree of membrane oxidation and ability to capture and convert light energy,promoting the growth of Solanum nigrum L.seedlings and alleviating the inhibitory effect of Cd stress on the growth of Solanum nigrum L.seedlings effectively,it was found that late stage(12~24 h)of spraying EBL had the best alleviating effect on Solanum nigrum L.seedlings after 600 mol/L Cd stress.This study provides a theoretical basis for exogenous application of EBL to improve the ability of plants to resist heavy metal Cd.