Characteristics Of Microbial Community Composition And Diversity In Rhizospheric Soil Of Edgeworthia Chrysantha Root-rot

Edgeworthia chrysantha is a deciduous shrub of the family Rhynchophyceae.Its whole plant can be used in medicine,and as one of the special economic tree species in China.The comprehensive and active economic development of E.chrysantha in mountain areas have a significant role.In recent years,rapid expansion of cultivation area and lack of reasonable management mode has caused an imbalance in microbiome of soil environment,and root rot disease has become one of the important factors limiting the yield of flowers and barks of E.chrysantha and its management benefits.To reveal the soil ecological mechanism of root rot of E.chrysantha,it is important to control the occurrence of root rot and to promote the sustainable management.In this study,the physicochemical properties,bacterial and fungal community composition and diversity of rhizosphere soils from the healthy and root-rotted E.chrysantha were analyzed to determine the key drivers of rhizosphere soil microbial community structure by Illumina sequencing,to reveal the mechanism of plant-soil-microorganism interactions in the process of root rot and to improve understanding of the pathogenesis and prevention and control of root rot of E.chrysantha.The main findings are as follows.(1)Comparative analysis hsowed that the relative abundances of bacteria and fungi communities in rhizosphere soils were significantly lower in the diseased plants than the healthy plants of E.chrysantha.However,no significant differences in microbial diversity indices between the diseased and healthy plants.Proteobacteria,Acidobacteriota,Actinobacteriota,Chloroflexi,and Verrucomicrobiota were the dominant bacterial phylum;Ascomycota,Mortierellomycota,Basidiomycota,Chytridiomycota,Glomeromycota were the dominant fungal phylum.(2)At the genus level,Byssovorax was significantly more abundant in the rhizosphere soil of the diseased plants than in that of the healthy plants of E.chrysantha.In soil fungal community,the abundance of Botryosphaeria,Sebacinales;f＿;g＿,Rhizophagus,Pseudallescheria,Monacrosporium,and Natipusillaceae;g＿were significantly higher in the rhizosphere soil of diseased plants than in those of the healthy plants.The above-mentioned genera could be the key genera in distinguishing the microbial community structure in the rhizosphere soil of between the healthy and diseased plants,and might be potential pathogenic microorganisms,with the most likely pathogenic microbes being Byssovorax,Botryosphaeria and Sebacinales;f＿;g＿.In addition,Fusarium＿solani was also the causal agent for root rot of E.chrysantha.(3)The correlation between soil physicochemical properties and root rot of E.chrysantha was analyzed.The occurrence of root rot was related to soil water content,p H,and organic carbon content.The increase of soil water content promoted the occurrence of root rot.Low soil p H may induce the development of root rot;the organic carbon content of the rhizospheric soil was significantly higher in root-rotted E.chrysantha than in healthy E.chrysantha.In summary,the damage by root rot caused a decrease in plant vigor and changed in the structure of bacterial and fungal communities in the rhizosphere soil as well as the soil environment.Therefore,in the future,prevention and control of root rot of E.chrysantha,attention should be paid to the changes in the soil environment.