ISOLAMENTO E CARACTERIZAÇÃO DE BACTERIÓFAGOS COM FOCO NA SUA UTILIZAÇÃO PARA CONTROLE DA MANCHA BACTERIANA DO TOMATEIRO

Abstract

Tomato bacterial spot is one of the most important diseases of this crop worldwide. Bacteriophages, viruses that infect bacteria, have been exploited in recent years as biocontrol agents for plant bacterial diseases. This study aimed to adjust the methodology for isolating phages from leaf and soil samples, aiming at prospecting for bacteriophages that can be used to control tomato bacterial spot. Samples of symptomatic and asymptomatic tomato leaves and soils near the plant were collected, and fourteen bacteriophages were isolated, and subjected to the host gamma test; from this sample, three phages (GF2, PL4 and S4) were selected to assess bacterial spot control. In the greenhouse, the effect of six treatments (water-control, copper hydroxide, PL4, S4, GF2, and mixtures of the 3 phages) was evaluated in relation to inoculation with two Xanthomonas spp. isolates (IFGO-X9 and IFGO-X5). The treatments were applied twenty-four hours before inoculation. Each treatment had four replicates, and the experimental plot consisted of a 1 L pot with a plant. There were differences among them in terms of host range. In the in vivo experiment, phages that had the ability to form lysis plates on pathogen isolates colonies also provided a reduction in the bacterial spot severity caused by these isolates. There was no severity reduction in the phage use when the pathogen isolate was not susceptible to it, as in the case of GF2 and IFGO-X9. The phage mixture was efficient in reducing the severity, since at least one of the phages is able to infect the pathogen isolate.