The Effect Of Exogenous Silicon On Soil Microbial Community Structure And Pathogenic Factors Of Ralstonia Solanacearum

Numerous studies have already documented Si can enhance plant resistance against a wide range of stress caused by various pathogens.But to date,most studies focus on the mechanism of silicon in enhancing plant resistance to foliar diseases,the effect of Si on soil-borne pathogens has attracted less attention.Moreover,the mechanism of Si in enhancing plant resistance against foliar pathogens cannot completely explain its role on soilborne pathogens.In this study,16 s rDNA and internal transcribed region(ITS)DNA techinques were adopted to analyze the rhizosphere microbiome component of Ralstonia solanacearum-infected soil by Si treatment and identify the role of Si in enhancing pathogen resistance.Transcriptome sequencing technology was also used to explore the effect of silicon on R.solanaceous.The main results were as follows:(1)Soil pH was increased when adding exogenous Si,and higher soil pH can directly inhibit the growth of R.solanacearum(2)Silicon did not influence soil bacterial and fungal community structure in the phylum level,but significantly affect bacterial community structure in the genus level,inhibiting the growth of pathogens such as Fusarium and Pseudomonas.(3)Exogenous Si could significantly influence the basal metabolism and the expression of some virulence factors in R.solanacearum.Si application significantly down regulated the expression of virulence genes xps R,rip AI,tek,Vrg of R.solanacearum.And the physiological experiments also showed that the amount of EPS synthesis and biofilms synthesis were reduced.These results suggested that exogenous Si significantly inhibit the pathogenicity of R.solanacearum,which may be one of the main reasons to reduce the incidence of tomato bacterial wilt.(4)Exogenous Si significantly up regulated the expression of ogt and the protein repair gene deg P in R.solanacearum,which indicated that silicon was potentially toxic to R.solanacearum.(5)Exogenous Si significantly down regulated the bacterial chemotaxis negative feedback control genes che Z,Fli N and up regulated the downstream flagella motor related genes pil E2,pil E and fim T.However,the mobility experiment showed that the application of silicon does not promoted the movement of R.solanacearumIn conclusion,we clearly demonstrate that silicon has significant effect on soil microbial community composition,Si can inhibit the growth of some pathogenic microorganisms.Transcriptomics analysis showed that silicon could significantly inhibit the expression of virulence genes in R.solanum and promote the expression of motor-related genes.The results will provide new evidence to explain the reduction of plant soil-borne diseases by Silicon.