Silicon impacts on soil microflora under Ralstonia Solanacearum inoculation

Silicon (Si) can increase plant resistance against bacterial wilt caused by Ralstonia solanacearum and enhance plant immune response. However, whether Si alleviates soil-borne disease stress through altering soil microbial community component and diversity is not clear. In this study, effects of Si application under R. solanacearum inoculation with or without plant on soil bacterial and fungal communities were investigated through high-throughput pyrosequencing technique. The results showed that Si addition significantly reduced bacterial wilt incidence. However, Si did not reduce the amount of R. solanacearum in rhizosphere soil. Principal components analysis showed that soil microbial community composition was strongly influenced by Si addition. Total 63.7% bacterial operational taxonomic units (OTUs) and 43.8% fungal OTUs were regulated by Si addition regardless of the presence of tomato plants, indicating the independent effects of Si on soil microbial community. Si-added soil harbored a lower abundance of Fusarium, Pseudomonas, and Faecalibacterium. Our finding further demonstrated that exogenous Si could significantly influence soil microbial community component, and this may provide additional insight into the mechanism of Si-enhanced plant resistance against soil-borne pathogens.