外源亚精胺对镉胁迫下黑麦草的生理调控效应

Physiological Regulatory Effects of Exogenous Spermidine on Ryegrass under Cadmium Stress

为解决植物修复重金属污染时遇到的耐性受损和低生长量等问题,研究了外源亚精胺(spermidine, Spd)对黑麦草镉(cadmium, Cd)胁迫的缓解效应。采用水培试验,在0、5和10 mg·L^(-1)Cd处理的基础上,添加0.1 mmol·L^(-1)Spd,定量考察分析了Spd对黑麦草生长发育、抗氧化能力和Cd积累特征的影响。结果显示,Cd处理显著抑制了黑麦草的生长和生理耐性。Cd浓度为10 mg·L^(-1)时,添加Spd使黑麦草生物量与耐性指数(tolerance index, TI)分别显著提高了20.90%和20.89%,叶绿素(a、b和a+b)含量显著提高了24.05%~46.11%。Spd还可抑制叶片内氧化产物丙二醛(malondialdehyde,MDA)和过氧化氢(hydrogen peroxide,H2O2)的积累,使其含量分别降低16.73%和16.45%;对抗氧化系统指标的影响则不一致,其中过氧化氢酶(catalase,CAT)、超氧化物歧化酶(superoxide dismutase,SOD)活性与抗坏血酸(ascorbic acid,ASA)含量分别显著上升了44.72%、100.12%和33.84%,过氧化物酶(peroxidase,POD)活性和谷胱甘肽(glutathione,GSH)含量无显著变化。而当Cd浓度为5 mg·L^(-1)时,添加Spd仅使叶绿素(a+b)、H2O2、ASA和GSH含量变化显著。此外,Spd也显著影响了黑麦草对Cd的转运和地上部积累,与5 mg·L^(-1)和10 mg·L^(-1)Cd单独处理相比,添加Spd使转运系数分别显著提高了7.07%和10.71%,使地上部Cd积累分别显著提高了8.98%和14.59%。本研究表明,添加外源亚精胺可通过调控上述指标改善Cd胁迫下植物的生长状况,增强生理耐性,同时还对其提取环境中的Cd有一定的促进作用。

To solve the issues of impaired tolerance and low growth encountered in phytoremediation of heavy metal contamination,the alleviation effect of exogenous spermidine(Spd)on cadmium(Cd)stress in ryegrass was investigated in this study.The effects of Spd on the growth,antioxidant capacity and Cd accumulation characteris-tics of ryegrass were investigated and analyzed using hydroponic experiment with the addition of 0.1 mmol·L^(-1) spermidine for 0,5 and 10 mg·L^(-1) Cd treatments.The results showed that Cd treatment significantly inhibited the growth and physiological tolerance of ryegrass.The addition of Spd at Cd concentration of 10 mg·L^(-1) increased the biomass and tolerance index(TI)of ryegrass by 20.90%and 20.89%,respectively,and the chlorophyll(a,b and a+b)content by 24.05%to 46.11%.Spd also inhibited the accumulation of oxidation products malondialde-hyde(MDA)and hydrogen peroxide(H2O2)in the leaves,reducing their contents by 16.73%and 16.45%,respec-tively;the effects on antioxidant indicators were inconsistent,the increases for the activities of catalase(CAT),su-peroxide dismutase(SOD)and the content of ascorbic acid(ASA)were 44.72%,100.12%and 33.84%,respec-tively,while peroxidase(POD)activity and glutathione(GSH)content did not change significantly.In contrast,when the Cd concentration was 5 mg·L^(-1),the addition of Spd caused significant changes in chlorophyll(a+b),H2O2,ASA and GSH contents.Moreover,Spd also significantly affected the translocation and aboveground accu-mulation of Cd in ryegrass,and the addition of Spd significantly increased the translocation coefficient by 7.07%and 10.71%,and the aboveground Cd accumulation by 8.98%and 14.59%,compared with 5 mg·L^(-1) and 10 mg·L^(-1) Cd single treatment.This study showed that the addition of exogenous spermidine could improve the growth of plants under Cd stress by modulating the above indicators and enhancing physiological tolerance,and could fa-cilitate the extraction of Cd from the environment.