Studying the microbiome of suppressive soils against vascular wilt, caused by Fusarium oxysporum in cape gooseberry (Physalis peruviana).

Cape gooseberry (Physalis peruviana) is Colombia's second most exported fruit, with a market worth 37.8 million USD in 2021. Fusarium oxysporum f sp. physalis (Foph) is arguably the most devastating pathogen causing losses of up to 80%. Managing this disease is challenging due to pathogen resistance or the reduced efficacy of commercial fungicides and the production of resistant structures allowing pathogen survival in the soil for up to 30 years. Thus, new methods of control are necessary. Two cape gooseberry farms (organic vs. conventional) were detected free from Foph in Nariño. We hypothesize that the soil microbiome might have a suppressive effect against vascular wilt, caused by Foph. To test this, farm soils were propagated by adding 10% farm soil and 90% peat soil. Then, peat soil (control) and propagated soils were inoculated with Foph. A decrease of 65%-68% in disease incidence and a 70% in disease severity reduction was observed in seedlings grown in propagated soils compared to peat soil. We then used next-generation sequencing to study the soil microbiome to understand the possible mechanisms for disease suppression of propagated soils. We conclude that despite the high diversity of soil microbiomes, the relative abundance of some taxa might be a more important indicator of disease suppression than the presence of specific taxa.

Effects of Fengycins and Iturins on Fusarium oxysporum f. sp. physali and Root Colonization by Bacillus velezensis Bs006 Protect Golden Berry Against Vascular Wilt.

Bacillus velezensis Bs006 has shown antagonistic activity on Fusarium oxysporum f. sp. physali and biocontrol activity against Fusarium wilt (FW) in golden berry (Physalis peruviana). We hypothesized that strain Bs006 has the ability to synthesize antimicrobial cyclic lipopeptides (CLPs) like other members of the same species. However, if so, the real effects of CLPs on F. oxysporum f. sp. physali and their potential as a biocontrol tool against Physalis-FW have not been elucidated. In this study the CLPs profile of Bs006 in liquid culture and antagonist-plant-pathogen interactions were characterized. Also, the potential effects of supernatant free of bacteria against F. oxysporum f. sp. physali and FW were explored and compared with the effects of pure CLPs. Ultraperformance liquid chromatography-electrospray ionization-mass spectrometry analysis revealed the capacity of Bs006 to synthesize homologous compounds of iturins, surfactins, and fengycins in liquid culture and on the inhibition zone against F. oxysporum f. sp. physali in dual confrontation tests. Bs006 supernatant reduced the germination and growth of F. oxysporum f. sp. physali and caused vacuolization, swelling, and lysis of F. oxysporum f. sp. physali cells in a concentration-dependent manner. Pure fengycins affected the development of F. oxysporum f. sp. physali from 11 mg/liter and iturins from 21 mg/liter. In a gnotobiotic system, Bs006 colonized the root surface of golden berry, inhibited the growth of F. oxysporum f. sp. physali, and produced CLPs. Individual application of Bs006 and supernatant protected the plants from F. oxysporum f. sp. physali infections by 37 to 53%, respectively. Meanwhile, fengycins reduced the disease progress by 39%. These results suggest further studies to select an optimum combination of Bs006 and supernatant or CLPs, which might be a good option as biofungicide against F. oxysporum f. sp. physali.

Efecto de la formulación sobre la vida útil de bioplaguicidas a base de dos aislamientos colombianos de Trichoderma koningiopsis Th003 y Trichoderma asperellum Th034 / The effect of the formulation on the shelf-life of biopesticides based on two colombian isolates of Trichoderma koningiopsis Th003 and Trichoderma asperellum Th034

Antecedentes. Se desarrollaron 4 prototipos de bioplaguicidas formulados como polvos secos para espolvoreo y granulados dispersables a base de 2 aislamientos colombianos de Trichoderma koningiopsis cepa Th003 y Trichoderma asperellum cepa Th034, microorganismos con actividad antagonista frente a Fusarium oxysporum f. sp. lycopersici y Rhizoctonia solani, con una reducción de la incidencia de entre el 70 y el 100% en cultivos de tomate y papa, respectivamente. Objetivo. Determinar el efecto de la formulación sobre la vida útil de 4 bioplaguicidas a base de T. koningiopsis Th003 y T. asperellum Th034 a 3 temperaturas diferentes. Métodos. El efecto de la formulación se determinó mediante la evaluación de la germinación de los conidios sin formular y formulados (granulado dispersable y polvo para espolvoreo) almacenados a 8, 18 y 28°C durante 18 meses. Con las cinéticas de germinación obtenidas se estimó la vida útil de los productos utilizando diferentes modelos matemáticos (orden cero, primer orden, segundo orden, modelo de Higuchi, modelo de Korsmeyer-Peppas y modelo polinomial). Resultados. Los productos presentaron una alta estabilidad de la germinación de los conidios cuando se almacenaron a 8 y 18°C, con vidas útiles de 14,4 y 13,9 meses para el polvo para espolvoreo a base de Th003 y de 12,0 y 10,8 meses para la formulación en polvo a base de Th034, respectivamente. Los prototipos formulados como granulados dispersables almacenados a las mismas temperaturas (8 y 18°C) presentaron menor vida útil, con valores de 11,6 y 10,9 meses para el producto de Th003 y de 10,7 y 7,2 meses para el granulado a base de Th034. En cuanto a los conidios sin formular, estos redujeron significativamente su germinación en todas las temperaturas de almacenamiento evaluadas. Conclusiones. El tipo de formulación afectó la estabilidad de los conidios de los 2 aislamientos colombianos de Trichoderma spp., siendo el polvo para espolvoreo el bioplaguicida que presentó la mayor estabilidad y vida útil en todas las temperaturas evaluadas(AU)

Background. Four biopesticide prototypes formulated as dispersible granules and dry powders based on 2 Colombian isolates of Trichoderma koningiopsis (Th003) and T. asperellum (Th034) were developed. These microorganisms have antagonist activity against Fusarium oxysporum f. sp. lycopersici and Rhizoctonia solani with a reduction in incidence of between 70 and 100% in tomato crops and potato crops, respectively. Aim. To determine the effect of the formulation on the shelf-life of 4 biopesticides based on T. koningiopsis Th003 and Trichoderma asperellum Th034 at 3 different temperatures. Methods. The formulation effect was determined by evaluating the germination of unformulated and formulated conidia (dispersible granules and dry powder) stored at 8, 18 and 28°C for 18 months. Germination kinetics were used to estimate the shelf-life by using different mathematical models (zero order, first order, second order, Higuchi model, Korsmeyer-Peppas model and polynomial model). Results. The products showed high stability of the conidia germination when they were stored at 8 and 18° C, with shelf-lives of 14.4 and 13.9 months for dry powder based on Th003, and 12.0 and 10.8 months for dry powder based on Th034, respectively. Prototypes formulated as dispersible granules stored at the same temperatures (8 and 18°C) showed lower shelf-lives, with values of 11.6 and 10.9 months for the Th003 product, and 10.7 and 7.2 months for the dispersible granules based on Th034. Significant reductions in germination were observed on unformulated conidia at all storage temperatures evaluated. Conclusions. The formulation type affected the conidia stability of the 2 Trichoderma spp. Colombian isolates. Dry powder was the prototype with the highest stability and shelf-life at all temperatures evaluated(AU)

Experimental mixtures of Phthorimaea operculella granulovirus isolates provide high biological efficacy on both Phthorimaea operculella and Tecia solanivora (Lepidoptera: Gelechiidae).

The Guatemalan potato moth Tecia solanivora (Povolny) recently invaded part of South America, colonizing zones where Phthorimaea operculella (Zeller), another potato moth species belonging to the same group, was previously established. T. solanivora is now the major insect pest of potato in this area encompassing Venezuela, Colombia and Ecuador. P. operculella granulovirus (PhopGV) (Betabaculovirus) is a biocontrol agent to be considered for the simultaneous management of these two potato pests, instead of classical chemical insecticides. In a previous work, five PhopGV isolates were isolated in Colombia from T. solanivora and were tested against larvae of the same species showing variable efficacies. Infections with mixtures of different genotypes of Baculoviruses had been carried out in a wide range of species and several showed interesting results. In the present study, the effect of sequential passages of PhopGV in P. operculella and T. solanivora larvae was analyzed through biological assays. Three different mixtures containing a Peruvian PhopGV isolate (Peru) adapted to P. operculella and a Colombian PhopGV isolate (VG003) adapted to T. solanivora were tested. A preliminary analysis of the correlation between the genotypic marker egt gene and the level of pathogenicity after a variable number of replication cycles was made. Mixtures of virus isolates showed a higher efficacy in both hosts compared to individual PhopGV isolates. This higher pathogenicity was maintained through passages. In P. operculella the mixtures were between 2.8 and 23.6-fold (from 7.15 OB/mm(2) to 0.10 OB/mm(2)) more pathogenic than isolate Peru applied alone. In T. solanivora they were between 2.3 and 4.9-fold (from 12.29 OB/mm(2) to 1.25 OB/mm(2)) more pathogenic than isolate VG003 alone. Viral biopesticide containing a mixture of selected genotypes active against each hosts seemed suitable for the development of a biopesticide aimed to simultaneously control P. operculella and T. solanivora.

[The effect of the formulation on the shelf-life of biopesticides based on two Colombian isolates of Trichoderma koningiopsis Th003 and Trichoderma asperellum Th034]. / Efecto de la formulación sobre la vida útil de bioplaguicidas a base de dos aislamientos colombianos de Trichoderma koningiopsis Th003 y Trichoderma asperellum Th034.

BACKGROUND: Four biopesticide prototypes formulated as dispersible granules and dry powders based on 2 Colombian isolates of Trichoderma koningiopsis (Th003) and T. asperellum (Th034) were developed. These microorganisms have antagonist activity against Fusarium oxysporum f. sp. lycopersici and Rhizoctonia solani with a reduction in incidence of between 70 and 100% in tomato crops and potato crops, respectively. AIM: To determine the effect of the formulation on the shelf-life of 4 biopesticides based on T. koningiopsis Th003 and Trichoderma asperellum Th034 at 3 different temperatures. METHODS: The formulation effect was determined by evaluating the germination of unformulated and formulated conidia (dispersible granules and dry powder) stored at 8, 18 and 28°C for 18 months. Germination kinetics were used to estimate the shelf-life by using different mathematical models (zero order, first order, second order, Higuchi model, Korsmeyer-Peppas model and polynomial model). RESULTS: The products showed high stability of the conidia germination when they were stored at 8 and 18° C, with shelf-lives of 14.4 and 13.9 months for dry powder based on Th003, and 12.0 and 10.8 months for dry powder based on Th034, respectively. Prototypes formulated as dispersible granules stored at the same temperatures (8 and 18°C) showed lower shelf-lives, with values of 11.6 and 10.9 months for the Th003 product, and 10.7 and 7.2 months for the dispersible granules based on Th034. Significant reductions in germination were observed on unformulated conidia at all storage temperatures evaluated. CONCLUSIONS: The formulation type affected the conidia stability of the 2 Trichoderma spp. Colombian isolates. Dry powder was the prototype with the highest stability and shelf-life at all temperatures evaluated.

LINKAGE MAPPING OF CANDIDATE GENES FOR INDUCE RESISTANCE AND GROWTH PROMOTION BY Trichoderma koningiopsis (Th003) IN TOMATO Solanum lycopersicum / Mapeo de genes candidatos relacionados con inducción de resistencia sistemica y promoción de crecimiento por Trichoderma koningiopsis (Th003) en tomate Solanum lycopersicum

Induced systemic resistance (ISR) is a mechanism by which plants enhance defenses against any stress condition. ISR and growth promotion are enhanced when tomato (Solanum lycopersicum) is inoculated with several strains of Trichoderma ssp. This study aims to genetically map tomato candidate genes involved in ISR and growth promotion induced by the Colombian native isolate Trichoderma koningiopsis Th003. Forty-nine candidate genes previously identified on tomato plants treated with Th003 and T. hamatum T382 strains were evaluated for polymorphisms and 16 of them were integrated on the highly saturated genetic linkage map named “TOMATO EXPEN 2000”. The location of six unigenes was similar to the location of resistance gene analogs (RGAs), defense related ESTs and resistance QTLs previously reported, suggesting new possible candidates for these quantitative trait loci (QTL) regions. The candidate gene-markers may be used for future ISR or growth promotion assisted selection in tomato.

La resistencia sistémica inducida (ISR) es un mecanismo mediante el cual las plantas aumentan sus defensas frente a cualquier condición de estrés. El objetivo de este trabajo fue localizar en el mapa genético de tomate, genes candidatos involucrados en ISR y promoción de crecimiento inducidos por la cepa colombiana nativa Th003 de Trichoderma koningiopsis. Se realizó una búsqueda de polimorfismos en cuarenta y nueve genes candidatos previamente identificados en plantas de tomate inoculadas con Th003 y la cepa T382 de T. hamatum. Diez y seis de estos genes candidatos fueron integrados en el mapa genético de tomate altamente saturado, llamado “TOMATO EXPEN 2000”. La ubicación de seis unigenes fue similar a la localización de genes análogos de resistencia (RGAs), ESTs relacionados con defensa y QTLs de resistencia previamente identificados, sugiriendo posibles nuevos candidatos para estas regiones de QTLs. Los genes candidatos o marcadores pueden ser usados en futuros programas de selección asistida relacionados con ISR o promoción de crecimiento en tomate.

Genetic and biological analysis of Colombian Phthorimaea operculella granulovirus isolated from Tecia solanivora (Lepidoptera: Gelechiidae).

Tecia solanivora (Lepidoptera: Gelechiidae) is an invasive potato pest of the north of South America that recently colonized zones where Phthorimaea operculella (Lepidoptera: Gelechiidae), a taxonomically related insect, was established. Nowadays, both species can be found in most areas in different proportions. The Phthorimaea operculella granulovirus (PhopGV) was found to efficiently control P. operculella and was used as a biopesticide in storage conditions. However, no appropriate biological control methods exist for T. solanivora, and the use of granulovirus isolates would provide a solution. The Colombian Corporation for Agricultural Research (CORPOICA) carried out several T. solanivora larva samplings in Colombia with the aim of finding potential isolates. Five geographical granulovirus isolates from T. solanivora (VG001, VG002, VG003, VG004, and VG005) were found, and molecular analysis by REN profiles shows three different genotypic variants in Colombia. Analysis of their genomes revealed their relatedness to PhopGV. Two isolates exhibited submolar bands in their REN patterns, suggesting a mixture of viral genotypes. These data were confirmed by PCR amplification and sequencing of particular regions of the viral genomes. Their biological activity was assayed on both hosts, T. solanivora and P. operculella. A significantly higher pathogenicity in both hosts was observed with isolates VG001 and VG005 than with isolate VG003 or a Peruvian isolate (from P. operculella) used as a reference in the bioassay. Based on their molecular and biological activity characteristics, VG001 and VG005 isolates should be selected for further analysis in order to establish their potential as biological control agents.

Eudragit S100 microparticles containing Spodoptera frugiperda nucleopolyehedrovirus: physicochemical characterization, photostability and in vitro virus release.

The aim of this study was to encapsulate the occlusion bodies (OBs) of Spodoptera frugiperda nucleopolyhedrovirus (SfNPV) in Eudragit S100 microparticles (MPs), considering this technique as a possible alternative to protect them from deleterious environmental conditions. The MPs were prepared by oil-in-oil emulsion (O/O) solvent evaporation method. Experimental conditions were established according to a previous multi-level experimental design involving the core/polymer ratio as independent variable. The effects of these parameters on particle size and process yield were investigated observing that polymer concentration had a significant effect on particle size. After adequate conditions for MPs formation were determined, virus was encapsulated. The virus microparticles presented a particle size between 50-300 microm and concentration was 2.62 x 10(9) OBs g(-1). Microencapsulation efficiency was 53.43% and virus release adjusted to Higuchi model suggesting diffusion as the release mechanism. Evaluated microencapsulation process protected viral particles of UV-inactivation, suggesting its potential for a biopesticide development.

Optimización de un medio de cultivo para la producción de la levadura Pichia onychis (Lv027) / Optimising culture medium for producing the yeast Pichia onychis (Lv027)

La optimización de la producción masiva de la levadura Pichia onychis fue investigada usando varios sustratos y evaluando diferentes condiciones físico-químicas de fermentación líquida. Inicialmente se realizó un screening aplicando el diseño estadístico Plackett-Burman para evaluar tres fuentes de carbono y ocho fuentes de nitrógeno (tanto orgánicas como inorgánicas) con el fin de seleccionar los factores nutricionales más influyentes sobre el crecimiento de la levadura. Posteriormente, se evaluaron cuatro fuentes nutricionales y dos variables físico-químicas utilizando un diseño factorial fraccionado como punto de partida, para llevar a cabo después un proceso de optimización aplicando un diseño estadístico Central Compuesto Rotacional. Un modelo de regresión polinomial se desarrolló usando los datos experimentales; los resultados muestran que la producción de biomasa fue afectada significativamente por condiciones tanto nutricionales como físico-químicas del medio de cultivo; el máximo rendimiento obtenido fue de 8,95 XlO9 células/mL equivalentes a una biomasa seca de 6,30 g/L, el cual se logró con las siguientes condiciones: 43,42 g/L de fuente de carbono, 0,261 g/L de fuente de nitrógeno orgánica, agitación de 110 rpm, pH = 6,0 con un tiempo de fermentación de 48 horas.

Optimising Pichia onychis yeast biomass production was evaluated using different substrates and different physicochemical conditions for liquid fermentation. The Plackett-Burman statistical design was initially applied for screening the most important nutritional variables (three carbon sources and eight nitrogen sources) affecting yeast biomass production. Four nutritional sources and two physicochemical variables were subsequently evaluated using a factorial fractionated design as the starting point for optimising the process by applying a central composite rotational design. The results obtained from employing a polynomial regression model using the experimental data showed that biomass production was strongly affected bynutritional and physicochemical conditions. The highest yield was obtained in the following conditions: 43,42 g/L carbon source, 0,261 g/L nitrogen organic source, shaking at 110 rpm, 6,0 pH, 48 h total fermentation time during which 8,95 XlO9 cells/mL were obtained, equivalent to 6,30 g/L dry biomass.