ABSTRACT. This study aimed to investigate the potential of rhizobacteria isolated from tomato plants to control Sclerotinia sclerotiorum and induce the activity of pathogenesis-related enzymes in Micro-Tom tomato plants. Three rhizobacterial isolates were evaluated to determine the most efficient antagonist agent, which was later identified by gene sequencing as Bacillus amyloliquefaciens PKM16. The antagonistic effects of B. amyloliquefaciens against S. sclerotiorum were assessed in vivo and in vitro using live and autoclaved cultures at concentrations of 0% (control), 20%, 30%, and 40% (v/v). The residual effects of four treatments (20% live culture, 20% autoclaved culture, a Bacillus subtilis-based commercial product, and autoclaved distilled water) on tomato plants inoculated with S. sclerotiorum were determined. The same treatments were also used to assess the myceliogenic germination of sclerotia and induction of plant defense enzymes (peroxidase, catalase, polyphenol oxidase, phenylalanine ammonia-lyase, and β-1,3-glucanase) in tomato plants. The live culture had a residual effect for 4 days and inhibited sclerotial germination by approximately 30%. Furthermore, live and autoclaved bacterial growth cultures stimulated enzyme activity. Therefore, B. amyloliquefaciens PKM16 was antagonistic to S. sclerotiorum, effectively inhibiting mycelial growth and activating defense mechanisms in Micro-Tom tomato plants.

Abstract The induction of resistance (IR) in plants by natural products has been the subject of several studies, these being activated by eliciting molecules of biotic or abiotic origin. Elicitors activate resistance mechanisms such as pathogenesis-related proteins (PRP’s), which act to protect plants by preventing pathogen development. The present study aims to verify the activation of PRP's (peroxidase, catalase, polyphenoloxidase and β-glucanase) in pyre corn plants (Zea mays) treated with different concentrations (0%, 0.5%, 1%, 1.5%, 3% and 5%) of the commercial biofertilizer Microgeo®. Analyzing the PRP’s enzymes, it was observed that the Microgeo® activated and increased the activity of these enzymes and that this induction is more related to the activation time, but not to the concentration used.

Resumen La inducción de resistencia (IR) en plantas por productos naturales ha sido objeto de varios estudios, siendo estas activadas por moléculas elicitoras de origen biótica o abiótica. Los elicitores activan mecanismos de resistencia como las proteínas relacionadas a patogénesis (PRP’s), que actúan en la protección de plantas impidiendo el desarrollo del patógeno. El presente estudio tiene como objetivo verificar la activación de PRP’s (peroxidasa, catalasa, polifenoloxidasa e β-glucanasa) en plantas de maíz pira (Zea mays) tratadas con diferentes concentraciones (0%, 0.5%, 1%, 1.5%, 3% y 5%) del biofertilizante comercial Microgeo®. Analizando las enzimas PRP’s se observó que el Microgeo® activó e incrementó la actividad de estas enzimas y que está inducción está más relacionada al tiempo de activación, pero no a la concentración utilizada.

RESUMO O objetivo do presente trabalho foi avaliar o progresso temporal das doenças ferrugem polisora (Puccinia polysora), cercospora (Cercospora zeae-maydis), mancha branca (Pantoea ananatis) e helmintosporiose (Exserohilum turcicum) no milho, bem como sua correlação com as variáveis climáticas. O delineamento experimental foi o de blocos completos com tratamentos ao acaso. O modelo monomolecular foi o que melhor se ajustou às epidemias. Com os dados de severidade de cada doença, foram elaboradas correlações com as variáveis climáticas (DFtemp-dias favoráveis com temperatura entre 18-28ºC; DFumid-dias favoráveis com umidade relativa>60%; PrecAcc-precipitação acumulada; PrecDia- precipitação/dia e Prec10-precipitação>10mm) observadas durante o período de avaliação. Após as análises pôde-se inferir que a variável precipitação acumulada foi determinante para a ocorrência de epidemias das doenças estudadas.

ABSTRACT The aim of the present study was to evaluate the temporal progress of the diseases southern rust (Puccinia hpspolysorahps), Cercospora leaf spot (Cercospora hpszeaehpsatn-atnmaydis), white spot (Pantoea hpsananatishps) and spot blotch (Exserohilum hpsturcicumhps) in corn, as well as their correlation with climate variables. Experimental design was in complete blocks with random treatments. The monomolecular model best fit to the epidemics. Using the severity data from each disease, correlations were established with the climate variables (DFtemp-favorable days with temperatures between 18-28 ºC; DFumid-favorable days with relative humidity>60%; PrecAcc-cumulative rainfall; PrecDia-precipitation/day, and Prec10- precipitation>10 mm) observed during the evaluation period. After analyses, it was possible to infer that the variable cumulative precipitation was determinant for the occurrence of epidemics of the studied diseases.