Journal of Plant Pathology & Microbiology

Abstract

In vitro Evaluation of Actinobacteria against Tomato Bacterial Wilt (Ralstonia solanacearum EF Smith) in West Showa, Ethiopia

Kassahun Sadessa Biratu, Thangavel Selvaraj and Tariku Hunduma

Ralstonia solanacearum EF Smith is one of the most important and widespread pathogenic bacterium that causes a wilt disease in vegetable crops including tomato (Lycopersicon esculentum Mill.) in West Showa, Ethiopia, mainly in the off-cropping season. In vitro study was conducted to screen indigenous actinobacteria for their antibacterial activity against tomato bacterial wilt pathogen, R. solanacearum. 210 soil samples were collected from three districts of West Showa Zone, Ethiopia. Of all soil samples, 86 morphologically distinct actinobacterial isolates were isolated. In the preliminary screening test, 52 isolates were selected showing inhibitory activity against the pathogen and further tested for their antibacterial activity under secondary screening test. In the secondary screening test, all the isolates appeared significantly different (P ≤ 0.05) in their inhibition against the target pathogen. Of these
isolates, efficient 36 isolates were selected and subjected to the cell free suspension test. All the 36 isolates showed significantly different (P ≤ 0.05) in their inhibition activity in the cell free suspension test. In both dual culture and cell free suspension test, totally 21 isolates showed inhibitory activity against the target pathogen. The actinobacterial isolate, Gosu-qoraS#196-1 had become superior antagonistic isolate against R. solanacearum and followed by Awaro S#174-2, Senkele S#132-5, Awaro S#183-1, Senkele S#133-3, Dhaga file S#113-1, Awaro S#176-4, Gabata S#21-1, Dhaga file S#128-2 and Awaro S#174-3 isolates. This study has concluded that the actinobacterial isolates having antibacterial activity against this target pathogen and also the investigated isolates can be used as one component of integrated disease management practice through detailed further test. Then, the further research on
the actinobacterial isolates should be focused on species identification, in vivo evaluation of the isolates against tomato bacterial wilt and further testing of its host range.