两种螯合剂对钴胁迫下紫花苜蓿种子萌发及钴富集的影响  

Effects of two chelates on germination and cobalt enrichment of cobalt-stressed alfalfa seeds

作　　者：伏毅[1] 王艳[1] 高鹏[1] 黄敏[1] 陈浩[1] FU Yi;WANG Yan;GAO Peng;HUANG Min;CHEN Hao(Sichuan Institute of Atomic Energy,Chengdu 610101,Sichuan,China)

机构地区：[1]四川省原子能研究院,四川成都610101

出　　处：《草业科学》2023年第12期3073-3083,共11页Pratacultural Science

基　　金：四川省重点研发项目(2018SZ0308、2023YFS0369)。

摘　　要：以紫花苜蓿(Medicago sativa)种子为材料,采用溶液培养法,研究金属螯合剂乙二胺四乙酸(EDTA)、乙二醇双(2-氨基乙基醚)四乙酸(EGTA)对钴(Co)胁迫下种子萌发及钴富集的影响,为植物在重金属环境中生长寻找解决办法,也为利用植物清除污染土壤中重金属元素提供潜在方法。通过不同浓度Co(0.1、0.2、0.5、0.7、1.0、20.0mmol·L^(-1))胁迫处理,探明Co胁迫对紫花苜蓿种子萌发的半抑制浓度为0.7 mmol·L^(-1),该浓度作为Co胁迫浓度,用于研究外源EDTA、EGTA对Co胁迫下紫花苜蓿种子萌发的影响。通过外源添加不同浓度EDTA(0.1、0.2、0.5、0.8、1.0、2.0 mmol·L^(-1))、EGTA(0.1、0.2、0.5、1.0、2.0、5.0 mmol·L^(-1)),测定EDTA和EGTA对Co胁迫条件下紫花苜蓿种子萌发的显著恢复浓度,并测定了显著恢复浓度下,紫花苜蓿种子体内超氧阴离子产生速率、超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量、Co含量等。结果表明,Co胁迫条件下,紫花苜蓿幼苗体内的超氧阴离子产生速率显著增加(P<0.05),而SOD活性显著降低,MDA含量显著升高,Co含量显著增加,达到2000 mg·kg^(−1)(以干重计)。外源0.8 mmol·L^(-1)EDTA和1.0 mmol·L^(-1)EGTA处理对Co胁迫紫花苜蓿种子发芽率和幼苗长度均得到显著恢复,幼苗体内超氧阴离子产生速率显著降低,SOD活性显著升高,MDA含量显著降低。研究证明,Co胁迫条件下,紫花苜蓿幼苗体内大量吸收Co,产生毒性作用,活性氧代谢平衡被打破是抑制紫花苜蓿种子萌发的原因之一,金属螯合剂EDTA、EGTA减少幼苗对Co的富集作用,对Co胁迫下紫花苜蓿种子萌发具有缓解作用。In this study,the seeds of alfalfa(Medicago sativa)and hydroponics were used as the materials and culture method,respectively,to investigate the effect of two metal chelating agents,ethylene diamine tetraacetic acid(EDTA)and ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid(EGTA),on the germination and cobalt enrichment of seeds under Cobalt(Co)stresses;to find potential solutions for plant growth in heavy metal environment and heavy metal removal from polluted soil by the plants.The seeds were first cultured at different levels of Co stresses(0.1,0.2,0.5,0.7,1.0,and 2.0 mmol·L^(-1))to ascertain the half-maximal inhibitory concentration of Co solution against the seed germination of alfalfa(0.7 mmol·L^(-1)).The Co solution at this concentration was then applied as the Co stress to study the effect of exogenous EDTA and EGTA on the germination of Co-stressed alfalfa seeds.Through exogenous addition of EDTA(0.1,0.2,0.5,0.8,1.0,and 2.0 mmol·L^(-1))and EGTA(0.1,0.2,0.5,1.0,2.0,and 5.0 mmol·L^(-1))at different concentrations to Co-treated groups,the significant recovery concentration of EDTA and EGTA for Co-stressed alfalfa seeds were determined.Meanwhile,superoxide anion generation rates(SAGRs),superoxide dismutase(SOD)activity,malondialdehyde(MDA)content,and Co content in alfalfa seedlings were determined when their germination was significantly recovered.The results revealed a significant increase(P<0.05)in SAGRs,MDA content,and Co content(reaching 2000 mg·kg^(−1))in the seedlings,whereas a significant decrease in the SOD activity.Both 0.8 mmol·L^(-1) exogenous EDTA and 1.0 mmol·L^(-1) exogenous EGTA can significantly recover the germination rates and seedling lengths of Co-stressed alfalfa seeds when SAGRs and MDA content in the seedlings significantly decrease,and the SOD activity significantly increases.The results indicate that one of the reasons for the inhibition of alfalfa seed germination is the imbalance of ROS metabolism caused by the toxic effect of Co when it is substantially

关 键 词：钴 种子 紫花苜蓿 活性氧 超氧化物歧化酶 EDTA EGTA 

分 类 号：S541.9[农业科学—作物学] X173[环境科学与工程—环境科学]