Prophylactic Application of Tailocins Prevents Infection by Pseudomonas syringae

Abstract

Tailocins are phage-derived bacteriocins that demonstrate great potential as agricultural antimicrobials given their high killing efficiency and their precise strain-specific targeting ability. Our group has recently categorized and characterized tailocins produced by and tailocin sensitivities of the phytopathogen Pseudomonas syringae, and here we extend these experiments to test whether prophylactic tailocin application can prevent infection of Nicotiana benthamiana by P. syringae pv. syringae B728a. Specifically, we demonstrate that multiple strains can produce tailocins that prevent infection by strain B728a and engineer a deletion mutant to prove that tailocin targeting is responsible for this protective effect. Lastly, we provide evidence that heritable resistance mutations do not explain the minority of cases where tailocins fail to prevent infection. Our results extend previous reports of prophylactic use of tailocins against phytopathogens, and establish a model system with which to test and optimize tailocin application for prophylactic treatment to prevent phytopathogen infection.

Interspecies killing activity of Pseudomonas syringae tailocins

“…syringae pv. syringae B728a ( Psy B728a) [8], and we further confirm killing of all these strains against Psy B728a here (). Furthermore, all strains also appear to have the same efficiency of activity against P.…”

“…Previous research suggested that the intraspecific killing spectrum of these tailocins is specific across closely related strains within the P. syringae complex [8, 25], but here we expand on these results and report that the killing activity of tailocins produced by P. syringae strain USA011R can be interspecific.…”

“…The single colony was then grown overnight in KB media plus rifampicin and frozen in 40 % glycerol at −80 ˚C. The creation of DBL1424 (a Rbp/chaperone deletion mutant of USA011R) and DBL1701 (a complementation strain derived from DBL1424) was described in [8]. These two genes are located at the 3′ end of a predicted tailocin operon and have also been shown that they are oftentimes exchanged together [25], allowing for simplicity of complementation [8].…”

“…Previous characterization of tailocins produced by the phytopathogen Pseudomonas syringae have shown that these tailocins can be effectively used as a prophylactic treatment for plant disease [8]. Previous research suggested that the intraspecific killing spectrum of these tailocins is specific across closely related strains within the P.…”

“…Alternatively, bacteriocins are natural antimicrobials produced by bacteria that are largely thought to precisely target and kill strains of the same or closely related species [7]. Since they are proteinaceous and non-replicative, it is possible that they could be applied as treatments under agricultural conditions with a reduced risk of environmental stress interfering with the effectiveness and with reduced worries over evolutionary dynamics [8–11]. Bacteriocins have also proven effective in the prevention or treatment for various plant diseases, but their use is somewhat limited by the necessity to find and characterize compounds that are effective against bacterial strains of interest (e.g.…”