Evaluation of the inhibition capacity of five different PGPRs on the pathogenic fungi Rhizoctonia solani

SAYAGO, P.; ALBARRACÍN ORIO, A.G.; JUNCOSA, F.; DUCASSE, D.A.

Foz do Iguazu

Workshop; Workshop Latinoamericano de PGPR; 2018

Rhizoctonia solani is an aggressive soil-borne pathogen distributed throughout the world, causing a wide variety of diseases in crops of agricultural importance such as cotton, potato, tomato and soybean among others. Primary methods for managing the disease have included planting resistant cultivars, the use of fumigant chemicals and agronomic measures such as crop rotation. However, none of these approaches has proven to be effective enough. As a sustainable alternative, the use of PGPR (Plant-Growth Promoting Rhizobacteria) as a biological control agent of the pathogen has been proposed. Mechanisms of biocontrol by PGPR include competition of niches, production of antifungal metabolites and enzymes, and the induction of resistance as well as growth promotion. The aim of this work was to evaluate the biocontrol efficiency of five different PGPR species against one isolate of R. solani. Three strains of Bacillus amyloliquefaciens (PS01, PS02 and PS03), one strains of Bacillus cereus (PS04) and one of Paenibacillus spp. (PS05) were evaluated. Co-culture tests on Potato Dextrose Agar (PDA) plates were used as a mean of testing the PGPRs inhibition capacity. Antagonism was evaluated by measuring the radial growth of the pathogen after 3-4 days of incubation at 28°C ±2. The strains identified as Bacillus cereus and Paenibacillus spp. did not show inhibitory capacity, while strain PS03 showed an inhibitory capacity superior to 74%, followed by strains PS01 and PS02 with values superior to 60%.