Study On The Response And Transport Mechanism Of Arbuscular Mycorrhizal Fungi-P.Austerisks Symbiosis System To Zn-Cd Stress

With the continuous development of industry and agriculture,the problem of soil heavy metal pollution in China is deteriorating.Cadmium is a form of heavy metal pollution with the widest distribution and the most serious impact in China,causing serious damage to the soil.At the same time,Cd and Zn have similar structural and environmental characteristics,and they are often coexisted,which makes the Cd pollution more complicated.How to safely and effectively solve Zn-Cd co-pollution has become an urgent need to ensure soil safety.In order to cope with the increasingly complex problem of heavy metal pollution,this study constructed a arbuscular mycorrhizal fungi-P.austerisks symbiosis system,and used semi-hydroponics test to compare and analyze the effects of AMF on the physiological indexes of P.austerisks growth and heavy metal transport in the body and the corresponding resistance mechanism.In this study,a stable AMF-P.austerisks symbiosis was firstly constructed.The effects of AMF on growth physiology and material assimilation of P.austerisks under different heavy metal stress were also studied.Studies have shown that heavy metal stress inhibited the growth and development of P.austerisks,while AM treatment significantly improved the biomass of P.austerisks.The mycorrhizal dependence was14.69%³96.83%,and AMF promoted P.austerisks root biomass.The light fitting curve of P.austeriskss implied exponential growth mode.AMF significantly increased Pnmax,of which the maximum increases under zinc,cadmium and combined stress were368.29%,40.64%and 166.40%,respectively.Inoculation of AMF increased the phosphorus uptake of P.austeriskss,which is one of the strategies of AMF to assist P.austeriskss to resist heavy metal stress.In addition,AMF alleviates the oxidative stress produced by heavy metals by increasing the activity of antioxidant enzymes.This related to the type and concentration of heavy metal stress applied.In order to analyze the mechanism of AMF on Zn and Cd in P.austerisks,the uptake and transport of Zn and Cd in P.austerisks under different heavy metal stress were investigated.Studies have shown thatIt differed in absorption and transport strategies of different heavy metals in the symbiotic system.Under low concentration of zinc stress,AMF promoted the transport of zinc to the shoots(TF _increased from 48.532%to 59.739%),and high concentration stress enriched in roots(TF _decreased from-41.332%to-11.024%);Under cadmium stress,AMF fixed cadmium in root system(TF _reduced from-32.946%to-11.113%).Under low concentration combined stress,AMF increased the concentration of zinc in roots and leaves.Under high concentration stress,the concentration of zinc in roots and leaves decreased,and the accumulation of zinc in stems was increased.However,both of them reduced TF_Zn(TF _reduced from-38.952%to-2.382%).Regardless of the stress level,AMF decreased the concentration of cadmium in roots and leaves of P.austeriskss under combined treatment.The distribution of zinc and cadmium in each vegetative organ follows the rule:root>stem.It can be seen that the P.austerisks-sclerotium symbiotic system can not only alleviate the toxic effects of Zn and Cd stress on the growth and development of P.austerisks,but also improve the plant's tolerance to Zn and Cd via regulating the transport of Zn and Cd.The strategy provides new theoretical and technical support and improves the shortcomings of traditional phytoremediation techniques.