Considerations for Using Bacteriophages in Plant Pathosystems
Jeffrey B. Jones, Aleksa Obradovic and Botond Balogh
from: Phage Therapy: Current Research and Applications (Edited by: Jan Borysowski, Ryszard Międzybrodzki and Andrzej Górski). Caister Academic Press, U.K. (2014)
Phages have the potential for controlling plant pathogens in the rhizosphere or phyllosphere. Success of phage in disease control requires that high populations of both phage and bacterium exist in order to initiate a chain reaction of bacterial lysis. Various factors exist that can hinder success of disease control. Physical factors in natural environments such as the presence of biofilms that trap bacteriophages, low soil pH which inactivates phages, low rates of diffusion of phages in soil that prevent contact with target bacteria, and inactivation of phages upon exposure to UV, all impact successful use of phages. Other considerations relate to the bacterial strains which exist in nature. The bacterial species may have a low or high degree of variation in sensitivity to bacteriophages. Therefore, phage selection for field use requires careful monitoring of strains in the field be done due to the potential for strain variation in the field and the likelihood for development of bacterial strains with resistance to the deployed bacteriophages. Application timing has also been shown to be an important factor in improving efficacy of bacteriophages. For instance, ultraviolet light is deleterious to bacteriophages and upon exposure phage populations plummet; therefore, evening applications of bacteriophages result in persistence of phages on leaf surfaces for longer periods of time and may result in improved disease control. Extending the period of time phages persist in the phyllosphere has been a major hurdle. Formulations have been identified which improve the persistence of bacteriophages on leaf surfaces; however, there is a need to identify superior formulations that extend the life on leaf surfaces from hours to days. Another strategy for maintaining high populations of phages has been to use non-pathogenic bacterial strains that are sensitive to the phage(s) or a closely related organism that does not cause disease on the plant host. Finally, bacteriophages may have value as part of an integrated management strategy read more ...