AUTHOR=Villamizar Sonia , Ferro Jesus Aparecido , Caicedo Juan Carlos , Alves L. M. C. 

TITLE=Bactericidal Effect of Entomopathogenic Bacterium Pseudomonas entomophila Against Xanthomonas citri Reduces Citrus Canker Disease Severity

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.01431

DOI=10.3389/fmicb.2020.01431

ISSN=1664-302X

ABSTRACT=<p>The bacterium <italic>Pseudomonas entomophila</italic> has been recognized as an exceptional species within the <italic>Pseudomonas</italic> genus, capable of naturally infecting and killing insects from at least three different orders. <italic>P. entomophila</italic> ingestion leads to irreversible gut damage resulting from a global blockage of translation, which impairs both immune and tissue repair systems in the insect intestine. In this study we isolated a <italic>P. entomophila</italic> bacterial strain from soil samples which displayed a strong activity against <italic>Xanthomonas citri</italic> subsp, <italic>citri</italic> (<italic>Xcc</italic>), the etiological agent of citrus canker disease. The antagonism potential of isolated bacteria against <italic>Xcc</italic> and its ability to reduce citrus canker severity was assessed both <italic>ex planta</italic> and <italic>in planta</italic>. Our findings show that pathogenicity assays in <italic>Citrus x limonia</italic> by pressure infiltration and spray with a mixture of <italic>P. entomophila</italic> and <italic>Xcc</italic> leaded to a significant reduction in the number of canker lesions in high susceptible citrus leaves, at 21 days post-infection. To the best of our knowledge this is the first report of antibacterial activity of <italic>P. entomophila</italic> against a phytopathogenic bacterium. Collective action of <italic>P. entomophila</italic> factors such as diketopiperazine production and the type 6 secretion system (T6SS) may be involved in this type of biological control of citrus canker. The results suggest that the <italic>P. entomophila</italic> strain could be a promising biocontrol agent acting directly against <italic>Xcc.</italic></p>