纳米金对绿豆(Phaseolus radiatus)种子萌发和幼苗生长的影响及其生理机制

Effects of gold nanoparticles on seed germination and seedling growth of mung bean(Phaseolus radiatus) and the underlying physiological mechanism

以绿豆种子作为受试对象,通过种子萌发和幼苗栽培实验,探明纳米金胁迫对绿豆的植物毒性及生理机制的影响。结果表明:纳米金对绿豆种子萌发和幼苗生长具有显著抑制作用;随着纳米金浓度的升高,绿豆种子的发芽势、发芽率、发芽指数、活力指数,幼苗的高度、根长、鲜重均显著下降,根长和鲜重的下降幅度显著高于苗高和茎叶鲜重,幼苗死亡率则显著上升;纳米金对绿豆幼苗生理特征具有显著影响,随着纳米金浓度的增高,幼苗叶绿素含量和叶氮含量显著下降;幼苗茎叶组织和根组织的超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性均表现出先升高后下降的趋势,丙二醛(MDA)含量显著上升,幼苗茎叶组织SOD、POD、CAT活性显著高于根组织,MDA含量显著低于根组织;纳米金对绿豆根部的植物毒性明显强于对茎叶的毒性,并随纳米金浓度升高而逐步增强;叶绿素含量和叶氮含量显著下降及氧化应激水平的变化是引起幼苗形态学变化的原因。研究结果为纳米金的安全应用和潜在生态风险评价提供了科学数据。

The phytotoxicical effects of gold nanoparticles on Phaseolus radiatus and the underlying physiological mechanism were examined in a seed germination and seedling cultivation experiment.The results showed that gold nanoparticles inhibited seed germination and seedling growth of P.radiatus.Seed germination characteristics(including seed germination potential,germination rate,germination index,and vigor index)and seedling growth indices(including seedling height,root length,and fresh weight)significantly decreased with the increasing concentration of gold nanoparticles.The decrease in root length and root fresh weight was more significant than that in seedling height and shoot fresh weight.An increased mortality rate of seedlings was associated with an elevated concentration of gold nanoparticles.The physiological characteristics of P.radiatus seedlings were significantly affected by gold nanoparticles.With the increasing concentration of gold nanoparticles,chlorophyll and nitrogen contents in leaves decreased,superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)activities in both shoot and root increased first and then decreased,and malondialdehyde(MDA)contents increased.The activities of those three anti-oxygen enzymes in shoot were higher than those in root,while the MDA content in shoot was lower than that in root.In conclusion,the phytotoxicity of gold nanoparticles was stronger in root tissues than in shoot issues,and this effect was concentration-dependent.Decreased chlorophyll and nitrogen contents in leaves and altered oxidative stress levels contributed to the morphological changes of seedlings.Our findings provide an important insight for the safe application and potential ecological risk assessment of gold nanoparticles.