Effects Of Phenanthrene And Copper Combined Contamination In Soil On Wheat Root Microbiome Cluster

Root microorganisms play an important role in regulating plant growth and development,nutrient absorption,abiotic and biotic stress.However,the recruitment strategies of the root-associated microbiome in combined organic and inorganic contaminated soils are not well known.In this study,we performed greenhouse experiments to investigate the interactive effects of joint copper(Cu)and phenanthrene(PHE)pollution on wheat growth and microbial detoxication processes.The results showed as follows :1.The root table played a role of filtering and screening for the colonization of microorganisms in the root.The structural composition of the microbial community in the root of wheat was different from that in the rhizosphere,and the significant decrease in the diversity of microorganisms in the root indicated that the root table had a selection effect on the microorganisms entering the root.2.Copper did not affect the degradation of phenanthrene in soil,but significantly promoted the accumulation of phenanthrene in wheat roots,while the addition of phenanthrene had no significant effect on the absorption of copper in wheat roots.It was found that copper was the main factor affecting the microbial community of wheat rhizosphere soil.3.Under the condition of phenanthrene and copper combined pollution,wheat can select and recruit bacteria that can degrade polycyclic aromatic hydrocarbons(PAHs)and are resistant to heavy metal copper to enrich in the rhizosphere environment.Examples are Novosphingobium,Sphingomonas,Sphingobium,and Pseudomonas.In addition,Bacillus,Methylobacterium,Lysobacter,Arthrobacter,Brevundimonas and Pseudomonas were found to be the most common bacterial species in China The ability to degrade hydrocarbons is a potential phenanthrene degrading bacterium.Actinobacteria,γ-Proteobacteria and α-Proteobacteria were found to be resistant to heavy metals.The interaction between organic pollutants,heavy metals,and root microbial communities appears to be weak,mainly due to the fact that over 90% of phenanthrene is degraded by functional degrading bacteria.Therefore,when carrying out bioremediation of contaminated sites in conjunction with root microbial communities,a comprehensive assessment of contaminant types,indigenous microbial composition and plant types should be carried out.In addition,considering the huge impact of copper on the degradation and accumulation of phenanthrene,it is also necessary to consider whether other common heavy metal pollution,such as cadmium and arsenic,has an impact on the degradation of phenanthrene during the restoration of the contaminated sites.This study provides a more comprehensive understanding of the interaction between organic-inorganic composite pollutants and plant-soil-microorganisms,and provides theoretical guidance for the regulation of plant self-repair process by root microbiome and the improvement of crop stress resistance in the future.