Isolation and characterization of bacterial strains from soybean rhizosphere as biopesticides

SIMONETTI E.; MONTECCHIA M.; PIN VISO N.; ZILLI CG; BALESTRASSE KB

Congreso; 32 New Phytologist Symposium; 2013

One novel strategy to control plant diseases is the use of antagonistic rhizobacteria. The aim of thepresent study is to isolate, identify and to select indigenous bacterial strains with antifungal activityfrom soybean plants growing in soils with disease-suppressive attributes. A total of 27 bacterialstrains were obtained in a preliminary screening, from the antagonism test plates where theconfluent growth of bacteria inhibited the development of fungal mycelia and microesclerotia ofMacrophomina phaseolina (Tassi) Goid. In search of efficient bacterial strains with multiple activities,a total of 6 bacterial isolates were characterized based on their morphological and biochemicalcharacters like production of indoleacetic acid, siderophore, phosphate solubilization and identifiedby 16S rDNA sequences as Stenotrophomonas sp., fluorescent Pseudomonas, Chryseobacterium sp.and Bacillus sp. Oxidative stress parameters were estimated in extracts of radicles emerged fromseeds that were treated with the rhizobacteria and inoculated with M. phaseolina. The resultssuggested that the damage severity on bacterized seeds was significantly reduced compared to nonbacterizedcontrol seeds. The protective action against the pathogen was accompanied by aninduction of antioxidant defenses. The rhizobacteria isolated in this work can be a useful tool toreduce charcoal root rot in soybean.