BIOCONTROLLING CAPACITY OF EXTRACELULLAR VESICLES FROM PLANT BENEFICIAL BACTERIA

GARACOCHE, DANA; OTERO, CAMILA; HUERGO, M. ANA; BIANCO, M.I; YARYURA, PABLO; CIMOLAI, M. CECILIA; COLUCCIO, LESKOW FEDERICO; MALAMUD, FLORENCIA

online

Congreso; Reunion conjiunta SAIB SAMIGE; 2021

Communication among bacteria through molecular mechanisms, like quorum sensing, is a well studied phenomenon. In the last years some evidence emerged showing that extracellular vesicles (EV) could function as nanoparticle messengers both in inter-species and trans-kingdom communication, this is well documented in the animal-microbiota interaction. Conversely there is no consensus on EV function in the various plant-bacteria relations (beneficial, commensal or pathogenic microbiota).The aim of this work is to unveil if plant growth-promoting rhizobacteria (PGPR) are able to exert its beneficial function through EV. Bacteria belonging to Bacillus spp are well known PGPR, and it was found that they are able to produce EV, with high concentration of bactericides, antimicrobial proteins and enzymes. Bacillus velezensis (VMA11m) was isolated from tomato from rhizosphere of healthy tomato plants in Córdoba, Argentina and in previous work it was found to show biocontrol properties against Xanthomonas vesicatoria, the causal agent of spot disease.In this study we found that VMA11m is able to produce biological functional extracellular vesicles. First we have evaluated the efficiency of these EV to control the spread of bacterial disease. We used cabbage and Xanthomonas campestris pv. campestris (Xcc), the causative agent of black rot in crucifers, as an experimental model for trans-kingdom communication. We have found a significant reduction in the pathogenic effect of Xcc when VMA11m EV were applied on leaves 24 hours before bacterial inoculation. We have also observed that these EV are capable of inhibiting Xcc growth in an in vitro assay. Ongoing experiments are being performed to find changes in expression of genes involved in the plant response to pathogen infection. Taken together these results suggest that VMA11m MV are, at least in part, responsible for the bio-controlling capacity of this bacterium.