The Influence Of Indole-3-acetic Acid On The Absorption And Accumulation Of The Soil Typical Organic Pollutant-Fluoranthene In Plants

In this study,the mechanism of the effects of the exogenous IAA on the absorption and accumulation of fluoranthene in plants was explored.The chosen of fluoranthene was due to its higher content in the soil in China,especially in the Yangtze River Delta region,and also was the priority control of the polycyclic aromatic hydrocarbons suggested by the US Environmental Protection Agency.Under the sterile culture,the effects of different fluoranthene and IAA concentrations on the absorption and accumulation of fluoranthene in ryegrass were studied;the effects of different concentrations of IAA on the absorption and accumulation of fluoranthene in two Arabidopsis thalianas with different sensitivity to auxin were studied,and an auxin inhibitor(N-(1-Naphthyl)phthalamic Acid,NPA)were used for further exploration.Besides,the effects of IAA on fluoranthene transport in Arabidopsis thaliana were studied.Finally,the possible mechanism was revealed by measuring the changes of physiological and biochemical indexes,and this might provide the theoretical basis for the phytoremediation of PAHs contaminated soil.The main results of the study are as follows:(1)The ryegrass was chosen and two fluoranthene concentrations(8,20 mg/L)and four IAA concentrations(0,1,5,10 mg/L)were set.The result showed that under the treatment of 8mg/L fluoranthene,at 5,10 mg/L IAA treatment the content of fluoranthene in the roots of ryegrass increased significantly.Under the treatment 20mg/L fluoranthene,the content of fluoranthene in the leaves and roots of ryegrass increased significantly,with the increase of IAA concentration,the transport ability of fluoranthene in ryegrass decreased,but there was no significant change between different IAA concentrations.In the leaves,the activities of CAT and PPO increased first and then decreased,POD activity increased significantly.In the roots,after the IAA addition,the activities of CAT increased significantly,and there was no significant change among the treatments of different IAA concentrations.The activity of POD activity decreased first and then increased.The correlation analysis showed that under the 20mg/L fluoranthene treatment,the content of fluoranthene in leaves was positively correlated with the CAT and SOD activities,the accumulation was positive correlated with the POD activity and biomass and the soluble protein content.The content of fluoranthene in roots was positively correlated with CAT activity and biomass,and the accumulation was positively correlated with the content of soluble protein,and negatively correlated with roots length.(2)Two Arabidopsis thaliana with different auxin sensitivity was chosen,including the auxin-sensitive wild-type Arabidopsis thaliana(WT),auxin-insensitive Arabidopsis thaliana mutant(Axr5),different IAA concentrations were set,and the effects on the absorption and accumulation of fluoranthene were studied.The result showed that after IAA addition,the content and accumulation of fluoranthene in WT-type Arabidopsis thaliana increased significantly with the decrease of IAA concentration,the fluoranthene content in the Axr5-type Arabidopsis thaliana was significantly reduced at 10-7,10-9,10-10 mol/L IAA treatment,and the accumulation of fluoranthene was significantly reduced at 10-5,10-9mol/L IAA treatment and the roots length increased significantly with the decrease of IAA concentration.The soluble protein content of WT-type Arabidopsis thaliana was significantly decreased at the higher concentrations of IAA treatment(10-5,10-6mol/L),the GST activity was significantly increased under 10-7,10-9 mol/L IAA treatment,the POD activity of 10-10,10-11mol/L IAA treatment significantly reduced.The soluble protein content and GST activity of Axr5-type Arabidopsis thaliana was significantly increased compared with the 10-11 mol/L IAA treatment,the POD activity decreased significantly with the decrease of IAA concentration.The correlation analysis showed that the fluoranthene content in WT-type Arabidopsis thaliana was positively correlated with plant root length,and the accumulation of fluoranthene was positively correlated with biomass and root length.The accumulation of fluoranthene in Axr5-type was positively correlated with biomass and root length.The influence of different NPA concentrations on the fluoranthene absorption and accumulation was also under research.The results showed that after NPA addition,the fluoranthene concentration in WT-type Arabidopsis thaliana did not change,but the accumulation of fluoranthene was significantly reduced,and there was no significant change between different NPA concentration treatments.But with the increment of the NPA concentrations,the fluoranthene content in Axr5-type Arabidopsis thaliana increased first and then decreased.The fluoranthene accumulation was significantly reduced at the higher concentrations of NPA(10 ?mol/L).The biomass of WT-type Arabidopsis thaliana was significantly reduced.Under the 10 ?mol/L NPA treatment,the biomass did not change compared with the control treatment.The biomass of Axr5 Arabidopsis thaliana increased significantly with the increment of the NPA concentration.After the NPA addition,the roots length of these two Arabidopsis thalianas were significantly reduced,and the reduction was more in the WT-type Arabidopsis thaliana than the Axr5-type Arabidopsis thaliana.(3)The fluoranthene transportation in two different auxin-sensitive Arabidopsis thalianas were examined with the IAA addition.The results showed that after IAA addition,in the leaves,the fluoranthene content of the WT-type Arabidopsis thaliana was significantly decreased,the content of fluoranthene in the roots were significantly decreased under the higher IAA concentration 10-6mol/L)treatment,and increased at the lower IAA concentration(10-10mol/L)treatment;The fluoranthene accumulation was increased significantly in the leaves,and was decreased in the roots under the higher concentration IAA treatment,while for the lower IAA concentration treatment,the fluoranthene accumulation in the roots increased significantly;The root length and plant height were significantly decreased under the higher concentration IAA treatment;After IAA addition,while the content of soluble protein in leaves was significantly increased,and there was no significant change between different IAA treatments;The CAT,GST,POD and PPO activities in leaves were significantly decreased,and there was no significant change between different IAA treatments;The transport capacity of fluoranthene was significantly enhanced under the higher concentration of IAA treatment,but significantly decreased under the lower concentration of IAA treatment.The correlation analysis showed that for the WT-type Arabidopsis thaliana,a significant positive correlation emerged between the fluoranthene concentration and the CAT,GST,POD activity,and a negative correlattion between the fluoranthene concentration with soluble protein and SOD activity in the leaves,the fluoranthene concentration and accumulation in the roots of Arabidopsis thaliana were positively correlated with root length.After IAA addition,the content of fluoranthene in roots of Axr5-type Arabidopsis thaliana was significantly reduced at the lower concentration of IAA treatment;under the higher concentration of IAA treatment,the content of fluoranthene in roots was significantly reduced.The biomass of the leaves was significantly increased,the root length;the content of soluble protein in leaves was significantly reduced,the POD activity in leaves was significantly decreased;The transport capacity of fluoranthene in the Axr5-type Arabidopsis thaliana was significantly enhanced.Under the lower concentration of IAA tratement,the CAT activity of roots were significantly increased,SOD activity was significantly decreased,the POD activity in leaves was significantly increased.The correlation analysis showed that a significant positive correlation between the fluoranthene content and the GST activity in the leaves.The content and accumulation of fluoranthene in the roots was positively correlated with root length and SOD activity,negatively correlated with GST activity.