Rhizosphere bacteria assembly derived from fumigation and organic amendment triggers the direct and indirect suppression of tomato bacterial wilt disease

Abstract

With no efficient method widely recognized for controlling or preventing tomato bacterial wilt, a devastating disease caused by the soil-borne bacterium Ralstonia solanacearum, tomato production is severely hindered. Therefore, the objective was thus to provide a strategy based on fumigation using ammonium bicarbonate along with organic amendment to reduce disease severity, and the impact of this treatment on the soil microbiome as well as the underlying mechanism leading to disease suppression were evaluated using high-throughput sequencing. Results showed that this combined strategy effectively controls tomato bacterial wilt disease despite the high abundance of R. solanacearum in both the bulk and rhizosphere soil in all treatments. The treatment led to significant changes in the soil bacterial and fungal communities, and at harvest time, fumigation and organic amendment equally affected the variation in the rhizosphere microbiome. Further, a shift in the rhizosphere bacterial community acted as the key factor directly and indirectly suppressing R. solanacearum and controlling bacterial wilt disease. In addition, Rhodanobacter, Terrimonas and Chitinophaga in the rhizosphere were the potential taxa involved in disease suppression. Both fumigation and organic amendment contributed to disease suppression by decreasing the abundance of R. solanacearum and altering the bacterial composition in combination with the stimulation of key bacterial taxa.