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Tailocins are ribosomally synthesized bacteriocins, encoded by bacterial genomes, but originally derived from bacteriophage tails. As with both bacteriocins and phage, tailocins are largely thought to be species-specific with killing activity often assumed to be directed against closely related strains. Previous investigations into interactions between tailocin host range and sensitivity across phylogenetically diverse isolates of the phytopathogen Pseudomonas syringae have demonstrated that many strains possess intraspecific tailocin activity and that this activity is highly precise and specific against subsets of strains. However, here we demonstrate that at least one strain of P. syringae, USA011R, defies both expectations and current overarching dogma because tailocins from this strain possess broad killing activity against other agriculturally significant phytopathogens such as Erwinia amylovora and Xanthomonas perforans as well as against the clinical human pathogen Salmonella enterica serovar Choleraesui s . Moreover, we show that the full spectrum of this interspecific killing activity is not conserved across closely related strains with data suggesting that even if tailocins can target different species, they do so with different efficiencies. Our results reported herein highlight the potential for and phenotypic divergence of interspecific killing activity of P. syringae tailocins and establish a platform for further investigations into the evolution of tailocin host range and strain specificity. 

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 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 in which 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. 

ABSTRACT Pseudomonas sp. strains 29A and 43A were originally isolated from the phyllosphere of individual plants of Cardamine cordifolia (Brassicaceae). Here, we report complete genome sequences for these two closely related strains, assembled using a hybrid approach combining Illumina paired-end reads and longer reads sequenced on an Oxford Nanopore MinION flow cell. 

Coevolution—reciprocal evolutionary change between interacting lineages (Thompson, 1994; see Glossary)—is thought to have played a profound role in the evolution of Life on Earth. From similar patterns across the wings of unrelated lineages of butterflies (Hoyal Cuthill and Charleston, 2015), egg mimicry of “cheating” brood parasites (Davies, 2010), to the role of animal pollinators in driving the diversification of flowering plants (Kay and Sargent, 2009), to the ubiquity of sexual reproduction and sexual conflicts (Hamilton, 2002; Arnqvist and Rowe, 2005; King et al., 2009), the formation of the eukaryotic cell (Martin et al., 2015; Imachi et al., 2020), and even the origin of living organisms themselves (Mizuuchi and Ichihashi, 2018), evolutionary changes among interacting lineages have played profound and important roles in the history of Life. This Grand Challenges inaugural contribution encompasses eclectic opinions of the editorial board as to what are the next frontiers of coevolution research in the 21st century. Coevolutionary biology is a field that has garnered a lot of attention in recent years, in part as a result of technical advances in nucleotide sequencing and bioinformatics in the burgeoning field of host–microbial interactions. Many seminal studies of coevolution examined reciprocal evolutionary change between two or a few interacting macroscopic species that imposed selective pressures on one another (e.g., insect or bird pollinators and their flowering host plants). Understanding the contexts under which coevolution occurs, as opposed to scenarios in which each partner adapts independently to a particular environment (Darwin, 1862; Stiles, 1978) is important to elucidate coevolutionary processes. A whole spectrum of organismal interactions has been examined under the lens of coevolution, providing additional context, and nuance to ecological strategies traditionally categorized as ranging from beneficial to detrimental for participating species (Figure 1). In particular, a coevolutionary perspective has revealed that even “mutualisms” are not always fully beneficial or cooperative for the partners involved. Instead, the tendency to “cheat” permeates across symbiotic partnerships (Perez-Lamarque et al., 2020). Conversely, recent evidence suggests that non-lethal predation by co-evolved predators, which has traditionally been assumed to be entirely antagonistic, may provide sessile prey with some indirect benefit through enhanced opportunities to acquire beneficial symbiotic microorganisms (Grupstra et al., 2021). Herein, we discuss some of the recent areas of active research in coevolution, restricting our focus to coevolution between interacting species. 

ABSTRACT Recently, we isolated a temperate bacteriophage, Pseudomonas phage Dobby, from a calcium oxalate kidney stone. Here, we present the complete genome of the bacterial host harboring this phage, Pseudomonas aeruginosa UMB2738. From the analysis of the genome sequence, five additional prophage sequences were identified. 

ABSTRACT Here, we present the genome sequence of a member of the group I Acidobacteria , Acidipila sp. strain EB88, which was isolated from temperate forest soil. Like many other members of its class, its genome contains evidence of the potential to utilize a broad range of sugars. 

ABSTRACT Microbiology Resource Announcements (MRA) provides peer-reviewed announcements of scientific resources for the microbial research community. We describe the best practices for writing an announcement that ensures that these publications are truly useful resources. Adhering to these best practices can lead to successful publication without the need for extensive revisions.