Hardian S. Addy,
Makoto Fujie, and
Takashi Yamada, Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
The wide host range of Ralstonia solanacearum, causal agent of bacterial wilt, and its ability to survive for long periods in the environment restrict the effectiveness of cultural and chemical control measures. The use of phages for disease control is a fast-expanding trend of plant protection with great potential to replace chemical measures. The filamentous phage φRSM3 that infects R. solanacearum strains and inactivates virulence on plants is a potential agent for controlling bacterial wilt in tomato. We demonstrated that inoculation of φRSM3-infected cells into tomato plants did not cause bacterial wilt. Instead, φRSM3-infected cells enhanced the expression of pathogenesis-related (PR) genes, including PR-1a, PR-2b, and PR7, in tomato plants. Moreover, pretreatment with φRSM-infected cells protect tomato plants from infection by virulent R. solanacearum strains. The effective dose of φRSM3-infected cells for disease prevention was determined to be approximately 105 CFU/ml. Because the φRSM3-infected cells can grow and continue to produce infectious phage particles under appropriate conditions, φRSM phages may serve as an efficient tool to control bacterial wilt in crops.