Effects Of Folsomia Candida On Root Properties And Cadmium Uptake Mechanism Of Sedum Plumbizincicola

As a representative of small soil arthropods,Collembola play an important role in soil nutrient cycling and energy flow,and can also affect plant growth.Previous studies have shown that Collembola have great potential in improving phytoremediation efficiency of metal contaminated soils,but the mechanism remains unclear.Collembola often live near and have close contact with roots,and can change the morphology of roots.We hypothesized that Collembola may affect plant growth and metal uptake by altering root properties.In this study,Folsomia candida,a typical small soil arthropod,and Sedum plumbizincicola,a cadmium and zinc hyperaccumulator,were used as experimental materials for soil pot experiments.Combined with plant transcriptome sequencing and 16 S r DNA high-throughput sequencing,the direct and indirect effects of F.candida on root properties and cadmium uptake of S.plumbizincicola were investigated.The main conclusions are as follows:(1)The dry weight of root and shoot increased significantly with the action of F.candida,with the highest increment of 53.3% and 34.4%,respectively.The root morphology of S.plumbizincicola changed significantly,and the total root length,root tip number and lateral root number increased by 40.7%,37.2% and 33.8%.The effects of F.candida on biomass and root properties of S.plumbizincicola were regulated by Collembola’s density.High density could reduce the promotion effect of Collembola on plant growth.The uptake of Cd and Zn by S.plumbizincicola roots was significantly increased by 83.2% and 65.4%,respectively.(2)F.candida affected plant hormone concentration and gene expression in S.plumbizincicola roots.F.candida’s feeding behavior caused biological stress to S.plumbizincicola roots.By the stimulation,the plant defense genes in the plant were activated,and the concentration of defense plant hormones in roots was increased,especially the concentration of salicylic acid was significantly increased by 3.38 times.The increased concentration of defensive plant hormones might promote lateral root formation and root growth.(3)With the influence of F.candida,soil microbial biomass C and N in present of S.plumbizincicola increased significantly by 1.43 and 0.42 times,respectively.The addition of F.candida significantly increased the utilization efficiency and microbial activity of different carbon sources by rhizosphere microorganisms.F.candida significantly affected the composition and function of rhizosphere and Endophytic microorganisms.Among them,the relative abundance of Devosia,Mesorhizobiuml and Actinomadura,which can promote plant growth,increased significantly.The relative abundance of saprophytic fungi increased significantly.F.candida indirectly promoted plant growth by affecting rhizosphere microbial composition and activity.F.candida can influence root morphology by activating S.plumbizincicola plant defense genes and promoting the synthesis of defense hormones.In addition,F.candida can affect microbial composition,function and activity.Ultimately promoting plant growth and Cd uptake.