Combination of endophytic bacteria and resistant cultivars improves control of Ralstonia wilt of tomato

The aim of this study was to evaluate the combined effect of endophytic bacteria and tomato cultivars with different resistance levels to Ralstonia solanacearum in the control of tomato bacterial wilt. Endophytic bacteria were successfully introduced into tomato seedlings by three methods: cutting of the hypocotyl, substrate drenching and seed microbiolization. One hundred and fifty endophytic bacterial isolates were screened in greenhouse assays. Two isolates, identified as Bacillus sp. and Serratia marcescens by 16S rDNA sequencing were the most promising. These isolates, when combined with tomato cultivars Drica, Caraíbe, Yoshimatsu, and Santa Clara, reduced the area under the disease progress curve (AUDPC) of bacterial wilt by 16 to 65%. Additionally, it was shown that antibiosis is not involved in the control of R . solanacearum by Bacillus sp. and S . marcescens . This study adds new isolates of endophytic bacteria as potential agents to control Ralstonia wilt in tomato and emphasizes the importance of combining these bacteria with host resistance in the management of the disease.