Isolation, characterization and evaluation of putative new bacteriophage species to control bacterial spot on tomato in Brazil

Abstract

Abstract Bacterial spot is a highly damaging tomato disease caused by several species of the genus Xanthomonas. Bacteriophages have been studied for their potential use as a biological control method for bacterial diseases. Parte superior do formulário In the present study, bacteriophages were obtained from soil and tomato leaves in commercial fields in Brazil with the aim of obtaining biological control agents against bacterial spot. Phage isolation was carried out through co-cultivation with isolates of Xanthomonas euvesicatoria pv. perforans (Xp), which was prevalent in the collected areas. In the host range evaluation, no phage was able to induce a lytic cycle in all bacterial isolates. Then, in the in vivo tests, when Xpisolates were sensitive to the used phages, we observed that the prior application of phage suspension led to a reduction in the severity of the disease. The disease control level provided by phage application was equal to or greater than that obtained by the use of copper hydroxide. Electron microscopy analysis showed that all phages had similar morphology, with head-tails structure, similar to those viruses of the order Caudovirales. The observed short, non-contractile tubular tails strongly indicated that phages belong to the family Autographiviridae. Phylogenetic analysis confirmed it, and revealed that the phages belong to the genus Pradovirus. The phages are closely related to each other and potentially belong a new species of the genus. These phages will be evaluated in future studies against other tomato Xanthomonads strains to assess their potential as biological control agents.