PHAGE-BASED BIOPESTICIDES: CHARACTERIZATION OF PHAGE RESISTANCE AND HOST RANGE FOR SUSTAINABILITY

A host range study was done to establish the efficacy of 7 phage biopesticides on a number of Erwinia amylovora isolates, closely related Erwinia species and non-Erwinia species from geographically distinct regions.
The Ontario E. amylovora isolates were 100% phage-sensitive and similarly 5 of 6 Quebec isolates were also 100% sensitive.
In British Columbia, sensitivity was reduced by at least 14%. Korean Erwinia pyrofolia isolates were 100% sensitive, but the Japan isolates had a variable sensitivity.
Within Ea110 and Ea29-7 E. amylovora phage-sensitive populations, 27 and 6 phage-resistant colonies were isolated and characterized, respectively.
Dualplex real-time PCR confirmed the isolates as E. amylovora and simultaneously checked for the presence of a prophage.
Prophages were detected in 24 of the phage-resistant Ea110 isolates, resulting in lysogeny as responsible for their resistance.
There was no detectable prophage in the 6 Ea29-7 phage-resistant isolates therefore resistance is thought to be the result of mutation.
For all phage-resistant isolates, resistance was gained against multiple phages used in our biopesticides.

XI International Workshop on Fire Blight

D.R. Roach, A.J. Castle, A.M. Svircev, F.A. Tumini

fire blight, lysogeny, mutation, real-time PCR, phage resistance

https://doi.org/10.17660/ActaHortic.2008.793.59