Control of charcoal rot disease by PGPR strains: The role of antioxidant system in soybean plants

ZILLI, C; SANTA CRUZ DM; SIMONETTI E.; HERNANDEZ A; CARMONA M; BALESTRASSE KB

Mar del Plata

Congreso; LI Reunión Anual de SAIB; 2015

Charcoal rot is a plant disease caused by the soil fungus Macrophomina phaseolina. The biocontrol agents Pseudomonas fluorescens 9 and Bacillus subtilis 54 were tested for their effectiveness against root rot of soybean caused by Macrophomina phaseolina. Both PGPR strains were isolated from disease suppressive soils in different locations of Santa Fe Province. The fungal strain was isolated from infected soybean plants showing root rot symptoms. The control of disease was determined according to the ability to avoid fungal colonization. Inoculation with strain 9 was the most effective treatment to control infection (54%).In situ production of ROS was evaluated by Schiff, DAB and NBT staining. Rootlets infected with M.Phaseolina showed a 2.3-fold increase on H2O2 levels. Strains 9 and 54 improved partially H2O2 content. None of the applied treatments was able to reverse the suppressive effect of the pathogen on O2?- production, while gene expression was downregulated in infected radicles. However, as a result of strain 9-fungus interaction, SOD, CAT, APOX and HO genes were overexpressed. In conclusion,fungal colonization was efficiently prevented by inoculation with P fluorescens 9. Its ability to improve ROS production and gene expression of antioxidant enzymes could be related to its capacity to control disease