Biocontrol of Rhizoctonia solani (Kühn) and Fusarium solani (Marti) causing damping-off disease in tomato with Azotobacter chroococcum and Pseudomonas fluorescens

El objetivo de este trabajo fue evaluar el efecto antagónico de la rizobacteria promotora del crecimiento vegetal Pseudomonas fluorescens UM270 hacia los hongos fitopatógenos Botrytis cinerea, Fusarium oxysporum, Fusarium solani y Rhizoctonia solani. También, se determinó la expresión de los genes phlD y hcnC de la cepa UM270 en presencia de los fitopatógenos durante bioensayos de antagonismo in vitro. Los resultados muestran que la cepa UM270 logra inhibir el crecimiento del micelio de B. cinerea (45%), F. solani (25%) y R. solani (24%) en diferente grado, mientras que para F. oxysporum (1%) no hubo inhibición significativa. Al analizar la expresión del gen phlD, se observó que los patógenos la modulan diferencialmente, ya que mientras B. cinerea induce su expresión, los demás patógenos la reprimen . En el caso del gen hcnC, B. cinerea y F. oxysporum no afectaron su expresión, mientras que F. solani y R. solani la inhibieron. Estos resultados sugieren que los fitopatógenos pueden modular la expresión de genes importantes para la síntesis de compuestos antimicrobianos en Pseudomonas fluoresces UM270.

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The Role of Salicylic Acid and Pseudomonas fluorescens in Systemic Resistance Against Rhizoctonia solani kühn in Guar (Cyamopsis tetragonoloba (l.) Taub.)

International Journal of Phytopathology ◽

10.33687/phytopath.006.01.1377 ◽

2017 ◽

Vol 6 (1) ◽

pp. 01-15

Author(s):

Montaser F. Abdel-Monaim

Keyword(s):

Salicylic Acid ◽

Rhizoctonia Solani ◽

Pseudomonas Fluorescens ◽

Root Rot ◽

Yield Components ◽

Growth Parameters ◽

Field Conditions ◽

Systemic Resistance ◽

Cyamopsis Tetragonoloba ◽

Damping Off

Rhizoctonia solani was found to be associated with root rot symptoms of guar plants collected from different fields in New Valley governorate, Egypt. All the obtained isolates were able to attack guar plants (cv. Local) causing damping-off and root rot diseases. R. solani isolates No. 8 (RG8) was the more virulent ones in the pathogenicity tests. Salicylic acid (SA) and Pseudomonas fluorescens (PF) individually or in combination were examined for their potential in suppression damping-off and root rot and growth promotion of guar plants in vitro and in vivo. Both SA and P. fluorescens either individually or in combination inhibited the growth of the tested pathogenic fungi.SA combined with P. fluorescens recorded the highest inhibited growth followed by P. fluorescens alone. Under greenhouse and field conditions, all treatments significantly reduced damping-off and root rot severity. The combination of SA and P. fluorescens was more effective than using them individually. Under field conditions, all these treatments significantly increased growth parameters (plant height and No. of branches plant-1) and yield components (No. of pods plant-1, weight of 100 seeds and total yield fed.-1 and Guaran content (gm plant-1) in both locations (El-Kharga and Mallawy Agric. Res. Stations) during growing season 2014.The combination of SA and P. fluorescens were recorded the highest growth parameters and yield components. Generally, the combination of SA and P. fluorescens recorded the best results for controlling damping-off and root rot diseases in greenhouse and field with addition improved plant growth and increased yield components in the field. In physiological studies, activity of defense-related enzymes, including peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), pathogenesis related (PR) protein (chitinase and β 1,3 gluconase), were increased in inoculated and non-inoculated plants treated with the SA and P. fluorescens either individually or in combination, during the experimental period. The combination of SA and P. fluorescens recorded the highest increase in activity of all enzymes. In general, the activity of these enzymes begins to accumulate after two days of treatment and reached maximum levels at 6 to 10 days, then the activities of these enzymes were decreased progressively. On the other hand, total phenols and lignin increased in guar plants inoculated with R. solani and treated with SA and P. fluorescens individually or in combination. The highest accumulation of phenols was recorded 8th days from application, while lignin recorded the highest level at 10th days from application. In the end, these results suggested that SA and P. fluorescens either individually or in combination may play an important role in controlling the guar damping-off and root rot diseases, though they have induction of systemic resistance in guar plants.

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Relationship between in vitro growth inhibition of pathogens and suppression of preemergence damping-off and postemergence root rot of white bean seedlings in the greenhouse by bacteria

Canadian Journal of Microbiology ◽

10.1139/m94-018 ◽

1994 ◽

Vol 40 (2) ◽

pp. 113-119 ◽

Cited By ~ 34

Author(s):

M. S. Reddy ◽

R. K. Hynes ◽

G. Lazarovits

Keyword(s):

Rhizoctonia Solani ◽

Disease Severity ◽

Fusarium Solani ◽

Root Rot ◽

Culture Media ◽

Pythium Ultimum ◽

Damping Off ◽

Bacterial Strains ◽

White Bean

One hundred and twenty diverse bacterial strains were screened under greenhouse conditions for their ability to protect white bean seedlings from preemergence damping-off caused by Pythium ultimum and Rhizoctonia solani and postemergence root rot by Fusarium solani f.sp. phaseoli. Preemergence mortality or root rot increased with an increase in the inoculum concentration of fungal isolates. For further testing, 200 propagules/g soil of P. ultimum, 3 propagules/g soil of R. solani, and log 3 conidia/g vermiculite of F. solani f.sp. phaseoli were used, as these rates provided an optimal level (approximately 50%) of disease severity. Bacterial strains suspended in sterile distilled water were added to pathogen-amended soil or vermiculite at log 7 colony-forming units/g soil or vermiculite prior to seeding. Final healthy stand and root rot were recorded 4 weeks after planting. Nine bacterial strains on P. ultimum, five on R. solani, and nine on F. solani f.sp. phaseoli provided significant (P = 0.05) suppression of disease severity compared with the nonbacterized control. Bacterial strains were also tested in vitro against the mycelial growth of the fungi on solid and liquid media. There was no relationship between the ability of bacterial strains to inhibit fungal vegetative growth on solid culture media and their ability to suppress pathogen activity in the greenhouse, but, for a few strains, the reduction in disease was linked to reduced growth of the pathogens in liquid media.Key words: White bean, damping-off, root rot, Pythium ultimum, Rhizoctonia solani, Fusarium solani f.sp. phaseoli.

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Efecto de microorganismos antagonistas en el control de la enfermedad denominada “Nectria” en la melina Gmelina arborea Roxb.

Revista Forestal Mesoamericana Kurú ◽

10.18845/rfmk.v0i0.2549 ◽

2016 ◽

Vol 13 (32) ◽

pp. 21 ◽

Cited By ~ 1

Author(s):

Marena Chavarría-Vega ◽

Randall Carmona-Solís

Keyword(s):

Bacillus Subtilis ◽

Costa Rica ◽

Pseudomonas Fluorescens ◽

Trichoderma Harzianum ◽

Fusarium Solani ◽

Azotobacter Chroococcum ◽

Trichoderma Asperellum ◽

Gmelina Arborea

Se evaluaron posibles métodos de control biológico a través de microorganismos antagonistas, por medio de pruebas en laboratorio en las cuales se puso a competir el organismo antagonista contra el agente patógeno causal de la enfermedad denominada “Nectria”, el cual fue determinado en éste mismo estudio. Adicionalmente, se realizaron pruebas de inoculación en vivero, así como ensayos en plantaciones forestales propiedad de la empresa Ethical Forestry S.A. en la Zona Norte de Costa Rica. Los resultados determinaron que el principal agente patógeno de la enfermedad es Fusarium solani. Las pruebas de laboratorio en las cuales se confrontaron los microorganismos antagonistas contra el patógeno, demostraron que tanto Trichoderma harzianum como Trichoderma asperellum generan resultados acertados en el control del patógeno, no obstante se reporta un crecimiento más agresivo de T. harzianum. A nivel de vivero, se obtuvieron diferencias importantes en los porcentajes de germinación en los tratamientos de T. harzianum más T. asperellum (52% superior) y Bacillus subtilis, Pseudomonas fluorescens, Azotobacter chroococcum (21% superior) respecto al tratamiento testigo; en cuanto a ensayos de campo la incidencia de la enfermedad en plantaciones de 21 meses de edad ha sido prácticamente nula, además a pesar de no encontrar diferencias estadísticamente significativas se ha podido notar un crecimiento superior tanto en diámetro (hasta 1,15 cm en promedio) como en altura (hasta 1,03 metros en promedio) en los tratamientos a base de microorganismos antagonistas.

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