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Soil is where most of the biodiversity on Earth exists, and the rhizosphere is probably the most dynamic habitat and certainly the most important area in terms of defining the quality and quantity of terrestrial human food resources. Despite its central importance to all organisms, very little is known about the functioning of the rhizosphere. The processes taking place in the rhizosphere play a key role in the nutrient circuit in terrestrial ecosystems. There is a growing need to understand the processes in the rhizosphere area so that we can effectively manage ecosystems or harness their potential benefits, either to mitigate or stop the negative consequences of anthropogenic intervention. [ABSTRACT FROM AUTHOR]

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RESUMO O ambiente rizosférico envolve diversas relações ecoflsiológlcas. A antibiose é parte desse contexto, servindo inclusive como mecanismo de seleção para as espécies mais adaptadas. Substâncias biológicamente ativas podem ser exudadas pelas raízes de algumas espécies vegetais ou extraídas através de solventes orgânicos, quando existe o interesse farmacológico. Raízes obtidas através de transformação genética de plantas de Agrobacterium rhizogenes abrem caminho para a obtenção de compostos bioativos sem as variações impostas pelo ambiente. Microorganismos, simbiontes ou não, tais como bactérias, actinomicetos e fungos também produzem substâncias de potencial atividade biológica. No vegetal a existência de tais metabólitos parece estar ligada a sua defesa química contra o ataque de patógenos enquanto nos microorganismos estas parecem servir também a uma melhor sobrevivência quando em ambientes competitivos.

Los hongos micorrícicos arbusculares (HMA) y los endófitos septados oscuros (DSEF) tienen tal influencia en el desarrollo de las plantas y en las características edafológicas y nutrientes disponibles en el suelo, que cambios en estas comunidades pueden impulsar modificaciones en las variables bióticas y abióticas de un ecosistema, demostrando la sinergia entre especies. Dada su relevancia, el objetivo de este trabajo fue determinar el estado de colonización en las raíces de tres especies herbáceas representativas del sotobosque de una comunidad de Abies religiosa (Kunth Schltdl. et Cham.) y Pinus harwegii (Lindl), y contrastar la coexistencia de colonizadores en tres escenarios de conservación-perturbación que ejemplifican las situaciones de vulnerabilidad de un ecosistema forestal. Se constata una interacción tripartita AMF-HESO-planta por la aparición de hifas coenocíticas, vesículas, hifas septadas, células moniliformes y esclerocios. Los valores de micorrización arbuscular superan el 50% y son superiores a los encontrados para los endófitos (15.7-64.5%). La colonización de ambos tipos de hongos, como la esporulación de AMF (687 esporas 50 g-1 de suelo en la zona reforestada), parece estar relacionada con las condiciones microclimáticas derivadas del uso del suelo. Las variables edafológicas que permiten inferir el comportamiento de la colonización corresponden principalmente al fósforo disponible, calcio, pH, materia orgánica y capacidad de intercambio catiónico. Se concluye que las propiedades del suelo, su uso y el tipo de plantas son determinantes en el establecimiento de las comunidades fúngicas. Sin embargo, son necesarios más estudios sobre la interacción HESO-planta.

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Rhizosphere microorganisms play an important role in the growth and health of plants. Around the world, diverse soil-borne pathogens attack Capsicum annuum causing significant damage and economic losses. This study determined whether the diversity and composition of microbial communities in the rhizosphere soil of C. annuum plants is significantly changed by wilt disease. We used the 16S rRNA gene for bacteria and the internal transcribed spacer region for fungi to characterize the rhizosphere microbiomes of healthy and wilted plants. The most abundant bacterial phyla were Proteobacteria and Gemmatimonadetes, while the most abundant fungal phyla were Ascomycota and Mucoromycota. The bacterial α-diversity did not show significant differences in richness and diversity, but did show a significant difference in evenness and dominance of species. Rare taxa were present in both healthy and wilted conditions with relative abundances < 1%. In the fungi, all evaluated estimators showed a significant reduction in the wilted condition. The β-diversity showed significant differences in the structure of bacterial and fungal communities, which were segregated according to plant health conditions. The same occurred when comparing the alpha and beta diversity of this study based on organic agriculture with that of other studies based on conventional agriculture. We observed a significant difference with estimators analyzed by segregating rhizosphere communities depending on the farming method used. Finally, the differential abundance analysis did not show significant results in the bacterial communities; however, in the fungal communities, Fusarium, Thanatephorus, Rhizopus, Curvularia, Cladosporium, and Alternaria were more abundant in the rhizosphere of wilted than healthy plants. Species from these genera have been previously reported as phytopathogens of several plants, including C. annuum. [ABSTRACT FROM AUTHOR]

Introduction. Phytopathogenic fungi represent the main economic losses worldwide in different types of crops, including vegetables such as Brassica Oleracea var. capitata. Objectives. Identify the possible phytopathogenic fungi associated with Brassica, the signs and symptoms they may cause, their possible transmission mechanism, and to qualitatively compare their growth in different culture media. Materials and methods. Leaves with and without symptoms were isolated, together with soil samples to elaborate serial dilutions. As for microscopy, the reproductive parts of the fungi were visualized for taxonomic classification. Results. A total of 17 morphotypes were isolated up to genus level, being Botrytis and Fusarium, the genera found with the highest presence in asymptomatic and symptomatic leaf samples. For soil samples, the most frequent genus was Penicillium. Conclusions. Of the three media evaluated, Sabouraud's extract agar showed the best results for the growth of most fungi. Probable transmission mechanisms were established for each of the fungi found in association with B. oleracea var. capitata and Botrytis sp. was established as the possible pathogen causing the symptoms observed in the samples. [ABSTRACT FROM AUTHOR]

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The amount of antibiotics being released into aquatic ecosystems is increasing, with negative repercussions for the environment and human health. Among the methods used to remove them is phytoremediation, a methodology based on using plants and microorganisms in the rhizosphere to remove pollutants from the environment. The technology that uses this strategy is the artificial wetland, composed mainly of plants, water and substrate. The objective of this review is to collect, organize and analyze the available information related to the interaction between bacteria and macrophytes in the antibiotic removal process. Initially, antibiotic contamination in water bodies and the toxic effects on living organisms are described, and the physical and chemical characteristics of antibiotics that influence their removal capacity are mentioned. Likewise, the process of antibiotic biodegradation by bacteria is described, as well as the plant-bacteria interaction that occurs mainly at the level of the plant roots (ectorizosphere, endorizosphere and rhizoplane), a process responsible for the removal of antibiotic compounds from the aquatic environment. This work aims to contribute to a better understanding of the plant-bacteria interaction process, in order to help optimize the design of a wetland to treat antibiotic residues from the aquatic environment, including a comprehensive review of the current knowledge. [ABSTRACT FROM AUTHOR]

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El objetivo de este trabajo es determinar los cambios en la estructura de la comunidad bacteriana en cultivos transgénicos de maíz así como su impacto en otras plantas. La metodología utilizada consistió en la búsqueda de publicaciones originales en cuatro bases de datos y su posterior filtrado por criterios de inclusión y exclusión. En los resultados se obtuvieron un total de 15 artículos de los cuales 13 comparaban un maíz transgénico con su contraparte hibrida o salvaje en su composición de rizosfera y endosfera y cuáles eran los cambios que estas presentaban, por otro lado 2 de estos artículos nombraban el cruce que puede existir entre un cultivo transgénico y uno no transgénico debido a su tipo de polinización. En conclusión, los cambios encontrados en la rizosfera y endosfera no son significativos y se deben a un proceso de adaptación de los microorganismos, además se deben tener unas normas mínimas para cultivar maíz transgénico, para proteger especies no transgénicas.

High mountain ecosystems have unique environmental characteristics, provide essential natural resources for the maintenance of life, and represent hotspots of biodiversity and endemism for animal and vegetal species. Within the vast diversity that characterizes high mountain environments, microbial diversity stands out due to its key role in the maintenance of soil stability and sustainability, promoting plant growth through the transformation of complex substances present in the environment into bioavailable forms, exerting biocontrol over phytopathogens or through the secretion of hormones and other compounds that allow better foliar and root development. Microorganisms establish important biological interactions with native plants in high mountains and páramos, including the different species of Espeletia, thus allowing to improve their role as regulators of water sources. Therefore, this review aims to consolidate the current knowledge about the microbial diversity present in high mountain soils, highlighting the microbiota associated with Espeletia spp. and their possible interactions. [ABSTRACT FROM AUTHOR]

Context: The use of biological inoculants or biofertilizers based on growth-promoting bacteria constitutes a sustainable biotechnological alternative to improve agricultural production. Knowledge gap: However, the environmental characteristics of agroecosystems can be very different between regions and these can have an effect on the growth and survival of such inoculants. Purpose: In this study, native microorganisms with plant growth-promoting capacity that can be used on crops in the Caribbean region of Colombia were isolated and characterized. Methodology: Rhizosphere bacteria were isolated from Capsicum sp. They were molecularly identified by 16S and their capacity to fix nitrogen in Ashby medium and to solubilize phosphate in NBRIP medium was determined. Inoculum of the identified bacteria were then applied to chili pepper plants and their effect on plant growth promotion was evaluated. Results and conclusions: The isolates were identified as Achromobacter sp., Bacillus mycoides, Bacillus sp., and Paenibacillus dendritiformis, and their application promoted plant growth, which was evidenced by the increase of at least one growth parameter, as well as nitrogen concentration in the tissues of chili pepper plants. Finally, Achromobacter sp. and B. mycoides were the inoculums with the best results, indicating their potential for use in agriculture in the region. [ABSTRACT FROM AUTHOR]

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Antecedentes: El biocontrol de las enfermedades fúngicas de la madera de la vid (EMV), es una alternativa amigable frente al control químico causante de resistencia y/o contaminación del ecosistema. Objetivo: aislar microorganismos nativos de raíz y rizósfera de vid con potencial de biocontrol de hongos de la madera de la vid. Metodología: Se estudió la “competencia por sustrato” (CS) con la escala de Bell, “el tiempo de contacto” (TC) entre antagonista-patógeno” (días) y la antibiosis por el porcentaje de inhibición del crecimiento (PIC). Resultados: Se aislaron e identificaron: siete-cepas de Trichoderma spp. (raíz: Tr-1, Tr-2, Tr3, Tr-6; y rizósfera: Tr-4, Tr-5, Tr-7); seis-Bacillus spp. (raíz: Bac-4, Bac-5, Bac-6; y rizósfera: Bac-1, Bac-2, Bac-3); y dos-Streptomyces sp. (rizósfera: Act-1, Act-2). Los resultados de la CS evaluados con la escala de Bell demostraron a Tr-1, Tr-7, T.atv (Trichoderma atroviride) y T-22 (Trichoderma harzianum) se ubicaron en la clase 1 frente a Lasiodiplodia theobromae y, todos los aislados se ubicaron en la clase 1 frente a Campylocarpon pseudofasciculare y Phaeoacremonium parasiticum. El TC de Trichoderma fue 2 días (L. theobromae) y 3 días (C. pseudofasciculare y P. parasiticum). En la antibiosis Tr-5 (Trichoderma) y Bac-3 (Bacillus) tuvieron el mayor PIC (>50%) frente a los patógenos. El aislado Act-2 (Streptomyces sp.) presentó PIC, >70% (L. theobromae), >40% (C. pseudofasciculare) y >30% (P. parasiticum). Implicaciones: El uso del control biológico en el manejo de enfermedades de la madera de la vid es una herramienta eficaz, y puede integrarse en una estrategia de manejo integrado de estas patologías. Conclusiones: Los aislados nativos Bac-3 (Bacillus spp.), Tr-5 (Trichoderma spp.), Act-2 (Streptomyces sp.) demostraron control in vitro frente a los patógenos L. theobromae, C. pseudofasciculare y P. parasiticum, patógenos asociados a enfermedades de la madera de la vid.

Las rizobacterias son un vasto y muy diverso grupo de bacterias que habitan en las inmediaciones de las raíces. Estas desarrollan relaciones tanto benéficas, neutrales e incluso perjudiciales, aunque estas últimas en menor medida. Las interacciones entre las bacterias y las raíces de las plantas han jugado un papel determinante en la adaptación y productividad de las especies vegetales a través del tiempo. Diversos estudios ponen en evidencia que las rizobacterias han mejorado el crecimiento, la producción y la salud de las plantas, directamente: mediante mecanismos que incluyen la asimilación de nutrientes vitales como la fijación de nitrógeno, solubilización de fósforo y potasio, y la fitoestimulación mediante la producción de diversas fitohormonas; e indirectamente: afectando el crecimiento de importantes fitopatógenos, activando la inmunidad en las plantas y mejorando los problemas ocasionados por estrés abiótico. Por su diversidad metabólica las rizobacterias podrían contribuir positivamente en la mejora de la productividad agrícola y la solución de problemas ambientales ocasionados por los métodos utilizados en la agricultura actual. Diversos géneros como: Acidithiobacillus, Aminobacter, Arthrobacter, Azoarcus, Azospirillum, Azotobacter, Bacillus, Burkholderia, Clostridium, Enterobacter, Gluconoacetobacter, Pseudomonas, Serratia y Sphingomonas han demostrado su enorme capacidad promotora de crecimiento. Esta revisión proporciona un enfoque sobre los mecanismos mediante los cuales las rizobacterias mejoran el crecimiento de las plantas, su contribución en la agricultura sustentable y su comercialización, un campo que continúa en constante crecimiento.

The article analyzes the importance of weeds in agroecosystems and their impact on agriculture. These plants affect soil nutrient uptake and increase the diversity of agricultural systems. Additionally, the importance of microorganisms in the plant rhizosphere is highlighted in promoting plant growth and improving soil quality. The role of weeds in the agroecosystem and their contribution to soil fertility is discussed, as well as their ability to resist pests and diseases. The importance of arbuscular mycorrhizal symbiosis in tropical ecosystems and its influence on microbial activity in the plant rhizosphere is also mentioned. [Extracted from the article]

Currently, food provision requires new tools that allow increasing the productivity of crops, without negative impacts on the environment. The plant rhizosphere is the soil part highly influenced by the root secretions. In this area, there is a high microbial activity, where different microorganisms, with agronomic applications, can live, and these can be used to develop products that contribute to face the challenges of current agriculture, such as the case of the bacterium Bacillus subtilis and different fungi species of the Trichoderma genus, which have been widely studied and used for the benefits that they give to plants. In this review, general characteristics of these microorganisms are described and the capacities these possess for their application in agricultural production, like an eco-friendly tool that helps to achieve food sovereignty, without the use of chemical compounds. [ABSTRACT FROM AUTHOR]

The short production cycle, high biomass production, and adaptability to various edofoclimatic conditions have led the eucalyptus to a prominent position in the world forestry sector. However, little is known about fungal community structure in these crops. This work aimed to evaluate the structure of soil fungal communities in eucalyptus forests as a function of rhizosphere effect and crop cycles of this crop. We used the independent PCR-DGGE method to evaluate the structure of the soil fungal community in Eucalyptus urograndis plantations located in the Vale do Rio Doce region, Minas Gerais, Brazil. The rhizospheric and non-rhizospheric portions of the soil were sampled in an area of recent forest establishment and in an area under multiple cycles. The principal component analysis revealed that the rhizosphere microenvironment is the dominant component in structuring the fungal communities in the areas studied, and this effect is more pronounced in the area of recent establishment of eucalyptus culture. The same pattern was found for the richness and diversity values, with the greatest differences found in the recently established area. In both studied areas the dominance of the order Agaricales prevailed, evidencing the role of the fungal community in the cycling of nutrients in the soil. [ABSTRACT FROM AUTHOR]

En el presente trabajo estudiamos el grado de tolerancia a metales pesados de hongos y bacterias aisladas de suelos con y sin rizósfera, con el propósito de conocer su potencial para aplicaciones en biorremediación. Las muestras procedían del pasivo minero de Santa Rosa de Jangas. Los hongos y bacterias aislados fueron identificados taxonómicamente mediante el análisis de la región ITS y 16S ADNr, respectivamente. El índice de tolerancia a metales pesados se calculó usando medio salino suplementado con 1 mM a plomo (II), cobre (II), niquel (II) o zinc (II), y 0.1 mM a plata (I), cromo (VI) o cadmio (II). En total se aislaron 23 hongos y 18 bacterias. Las cepas de hongos con mejores índices de tolerancia fueron: Fusarium temperatum CTLM05 (Pb+2), F. temperatum CTLM08 (Zn+2), F. oxysporum CTLM18 (Ni+2 y Cd+2), F. oxysporum CTLM12 (Ag+1), F. inflexumCTLM22 (Cu+2) y Penicillium vanluykii CTLM11 (Cr+6). Las cepas de bacterias con mayores índices de tolerancia fueron Bacillus licheniformis SSR18 (Cd+2, Ni+2 y Zn+2), B. subtilis SSR3 (Pb+2), Serratia sp. SSR15 (Cu+2), Serratia sp. SSR13 (Ag+1) y B. cereus SSR01 (Cr+6). También se encontró que los hongos mostraron mejores índices de tolerancia que las bacterias. Finalmente, los suelos del pasivo ambiental minero de Santa Rosa de Jangas poseen una microflora interesante, probablemente con mecanismos para su adaptación, crecimiento y desarrollo sobre metales pesados y pueden ser de utilidad para el desarrollo de procesos biotecnológicos y biorremediación.

Los oxisoles de la altillanura en Colombia contienen hasta 400 mg/kg de fósforo. Sin embargo, la fracción disponible para las plantas es inferior a 3,5 mg/kg, lo que obliga la suplementación con fertilizantes fosfóricos. Las plantas pueden adaptarse a estas condiciones por medio de interacciones con bacterias solubilizadoras de fosfatos (BSF) presentes en el suelo. Los oxisoles serían una potencial fuente de BSF; no obstante, existe un desconocimiento de su diversidad en la altillanura colombiana. El objetivo de esta investigación fue aislar, caracterizar e identificar BSF de oxisoles de la altillanura colombiana. A partir de muestras compuestas de suelo con cultivos transitorios y sabana, se obtuvieron 42 aislamientos. De estos, 14 cepas mostraron índices de solubilización de fosfatos entre 1,2 y 2,4. Las cepas M15 y M18 se seleccionaron por su alta actividad de las fosfatasas ácidas con 297,7 ± 89,6 y 638,3 ± 31,2 μg de p-nitrofenilfosfato/mL/h, respectivamente. Los dos aislamientos promovieron el crecimiento vegetal en plantas de arroz en condiciones de invernadero. Mediante la secuenciación parcial del gen 16S rRNA, las dos cepas fueron identificadas dentro del género Burkholderia. Esta investigación amplía el conocimiento de las BSF presentes en los oxisoles de la altillanura colombiana, así como sus capacidades para favorecer la disponibilidad de fósforo en el suelo y promover el crecimiento vegetal.

O Cerrado é um hotspot mundial de biodiversidade e vem sofrendo com a expansão das áreas destinadas produção de commodities. Mais da metade de sua área foi desmatada ou transformada por ação antrópica, incluindo a introdução e/ou expansão de plantas oportunistas. Atualmente, inúmeras espécies se tornaram invasoras de ambientes naturais do bioma. Buscando mitigar este processo invasivo, a utilização de espécies nativas que inibam o desenvolvimento das plantas invasoras e ao mesmo tempo favoreçam a biodiversidade nativa representa uma estratégia promissora. Dessa forma, este estudo avaliou o potencial alelopático da rizosfera de plântulas de Hymenaea stigonocarpa (jatobá-do-cerrado) na germinação e crescimento inicial das espécies invasoras, Megathyrsus maximus e Ipomoea triloba, e da cultivada, Sesamum indicum, plantadas em solo previamente ocupado por plântulas de jatobá-do-cerrado. Ademais, avaliou-se o efeito fitotóxico do extrato aquoso de suas raí­zes em coleóptilos de Triticum aestivum, usando o percentual de inibição do seu crescimento. As espécies alvo plantadas em solo previamente ocupado por plântulas de jatobá-do-cerrado apresentaram inibição significativa do crescimento em comparação ao controle. A inibição do crescimento de S. indicum foi de 31% da parte aérea e de 48% da radicular; enquanto M. maximum teve inibição de 41 e 84%, respectivamente. Já I. triloba não germinou. Contudo, não se observou alteração significativa do alongamento dos coleóptilos de T. aestivum expostos ao extrato de jatobá-do-cerrado. Os resultados obtidos sugerem potencial atividade alelopática desta nativa sobre plantas daninhas, indicando seu uso como estratégia em processos de recuperação de áreas degradadas do Cerrado com o benefí­cio de controlar o desenvolvimento de invasoras.

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El género Vaccinium spp. crece de forma silvestre en los páramos de los Andes. Sus frutos son reconocidos por presentar propiedades antioxidantes y nutricionales El objetivo de la investigación bibliográfica fue comprender la ecología del cultivo, la composición química del fruto y el efecto que poseen los microorganismos endófitos y aquellos asociados a la rizosfera en el crecimiento y desarrollo de Vaccinium sp. Las especies silvestres de Vaccinium han presentado baja variabilidad genética, a diferencia de la alta variabilidad de las especies cultivadas. Por ende, para cultivar las especies silvestres en diferentes épocas del año y lograr su producción de forma permanente y en varias localidades es necesario la domesticación de la misma. Esta domesticación, se puede realizar mediante estudios genéticos, fisiológicos, requerimientos edafoclimáticos y análisis de las interacciones de microorganismos con la planta, entre otros componentes. Una de las principales limitantes del género Vaccinium son las enfermedades provocadas por hongos, como Botrytis sp. y Hemileia vastatrix. No obstante, otros microorganismos endófitos y de la rizosfera de Vaccinium interaccionan de forma positiva con la planta favoreciendo la absorción de nutrientes, ofreciendo protección contra enfermedades e incluso mejorando la estructura del suelo. La diversidad del microbioma asociado a la rizosfera de la planta, así como la diversidad genética de Vaccinium floribundum son aspectos importantes que deben ser estudiados para establecer un programa de mejoramiento genético de esta especie y seguir con su domesticación.

Introducción y objetivos: Las especies de algas y Cyanobacteria que crecen en sitios contaminados pueden acumular altas concentraciones de metales pesados. En este trabajo se propuso a) caracterizar la comunidad de algas y Cyanobacteria y b) evaluar el efecto del plomo (Pb) sobre la composición de algas presentes en la rizosfera de plantas capaces de acumular Pb en la provincia de Córdoba. M&M: Se tomaron muestras de suelo de la rizosfera de Sorghum halepense, Bidens pilosa y Tagetes minuta en sitios con diferentes niveles de Pb. En el laboratorio, el suelo se sembró en cápsulas con medio de Watanabe esterilizado. Los cultivos crecieron 9 semanas. Se identificó en el tiempo y analizó la frecuencia relativa final de las algas y Cyanobacteria. Resultados: En suelos contaminados se identificaron 24 especies de Cyanobacteria, Chloroplastida y Xanthophyceae. Las Cyanobacteria con heterocitos Cylindrospermum muscicola, Nostoc commune y Calothrix clavata registraron una frecuencia media relativa (entre 21 y 60%). Trebouxia parmeliae (Chloroplastida) y Vaucheria sp. (Xanthophyceae) estuvieron presentes en los suelos con mayor nivel de Pb. La mayor parte de las especies se concentraron en los niveles más bajos de Pb. Conclusiones: Se observó un efecto negativo del Pb sobre la riqueza de especies de algas y Cyanobacteria en la rizosfera de las plantas evaluadas. En base a la composición de la comunidad de algas y Cyanobacteria del suelo se determinan dos grandes grupos que podrían ser considerados como comunidades tolerantes y no tolerantes a la contaminación de Pb.

The competition between weeds and crops is a topic of great interest, since this interaction can cause heavy losses in agriculture. Despite the existence of some studies on this subject, little is known about the importance of soil microorganisms in the modulation of weed-crop interactions. The competition between weed plants and crops promotes changes in the microbial community of the soil. The objective of this work was to determinate microorganisms in the rhizosphere of weed plants. In a Red Ferralitic soil, six experiments were conducted to know the possible benefits of timely management of weeds in corn (Zea mays L.) and bean (Phaseolus vulgaris L.) crops in a successional system for which the structural changes of the weeds and the influence of these on the fertility and presence of soil microorganisms were determined. The dominant species of weed was Sorghum halepense L. in both crops. The interspecific weed-crops relationships increased the nutrients and biodiversity associated with the productive system. 31 species of weeds were recorded (15 in corn and 16 in beans). Amaranthus dubius L., S. halepense L., Parthenium hysterophorus L., and next to them, Eleusine indica L. and Lepidium virginicum L., harbored the highest amount of microorganisms in the rhizophore. [ABSTRACT FROM AUTHOR]

Plant growth promoting bacteria are known to directly or indirectly influence the development and yield of plants. Studies that show the biotechnological potential of these bacteria as biofertilizers are thus important. The objective of this study was to evaluate the growth capacities of strains M2-7 and LYA12 and define whether their interactions with Capsicum annuum L. increases production. The hypothesis was that the Bacillus licheniformis strains have capacities to promote growth and yield of Capsicum annuum L. First, these strains were evaluated in vitro in selective culture media to detect those direct or indirect mechanisms for plant growth promotion. Then, the effect of both strains on seed germination and the effect of strain M2-7 were studied on the in vivo development of C. annuum L. The experimental design was completely randomized with 3 treatments and 3 repetitions. Data was analyzed with ANOVA and Tukey test (p£0.05). Results showed that the bacterial strains were able to fix nitrogen, solubilize tricalcium phosphate Ca3 (PO4)2, produce gibberellins, lytic enzymes (amylases, proteases, lipases and esterases), biosurfactants, volatile compounds; and significantly inhibit growth (p£0.05) of the phytopathogenic fungus Colletotrichum sp. Likewise, the strains M2-7 and LYA12 increased (p£0.05) by 89 and 78% the seed germination of C. annuum L. M2-7 enhanced fresh weight (235%), stem diameter (308%), root weight, number and weight of fruits (316%), as compared to treatment 1 (Nitrofoska) and 3 (Control). Therefore, B. licheniformis M2-7 strain is attractive to develop the formulation of biofertilizers; aiming to improve yield of some horticultural crops towards a sustainable and ecological agriculture. [ABSTRACT FROM AUTHOR]

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Las comunidades vegetales micróf ilas y xeróf ilas en el norte de Chihuahua se desarrollan en condiciones de estrés climático y ambiental. Se considera que esta resistencia puede estar relacionada con la presencia de hongos micorrízicos de tipo vesículo arbusculares (HMVA). El objetivo de este trabajo fue relacionar el tipo de suelo con la presencia de HMVA en la rizósfera de las plantas de matorrales desérticos, como una posible respuesta a la resistencia de las plantas bajo condiciones ambientales extremas en las comunidades vegetales del área natural protegida (ANP) médanos de Samalayuca, Juárez, Chihuahua. Durante los meses de marzo a octubre de 2016, se realizaron dos muestreos dirigidos seleccionando cuatro puntos de muestreo con base en el tipo de comunidad vegetal registrada en campo. Los transectos fueron de 100 m, se generaron diez parcelas de 20 × 25 m2 en cada zona y para cada parcela se registró el número de individuos por especie vegetal. Los índices de Shannon, Simpson, Pielou y Morisita fueron utilizados para el estudio de las comunidades. Se tomaron submuestras de suelo de 500 g a una profundidad de 0 a 30 cm en cada sitio de muestreo. Los análisis físicos y químicos de suelo fueron pH, textura, conductividad eléctrica, porcentaje de humedad, nitrógeno mineral y fósforo extractable. La extracción y conteo de esporas de HMVA se realizó por medio de tamizado húmedo, decantación y centrifugación en solución sacarosa al 70%. Se determinaron tres tipos de comunidad vegetal: matorral inerme parvifolio, matorral mediano subinerme y matorral de médanos. La especie con mayor presencia y dominancia fue Larrea tridentata. Los suelos del área estudiada resultaron ser arenosos, alcalinos, con baja salinidad y contenido de nitrógeno y altos de fósforo. Los géneros de HMVA encontrados fueron: Gigaspora, Acaulospora, Glomus y Paraglomus. El análisis de correlación de Pearson indicó que no existe relación estadística significativa entre la cantidad de nitrógeno inorgánico con la densidad de las esporas de HMVA (r = 0.585), mientras que para el fósforo se detectó una significativa relación entre su concentración y la densidad de esporas (r = 0.987). La relación entre la cantidad de esporas y concentración de nutrientes del suelo demuestra que entre más bajo en nutrientes es menor el número de esporas, sin embargo, no se puede determinar directamente la resistencia de las plantas con la presencia de los HMVA.

En la Empresa Pecuaria Genética "Niña Bonita" se realizó un experimento con el objetivo de evaluar la efectividad de la biofertilización con hongos micorrízicos arbusculares en el pasto Yacaré (Urochloa híbrido cv. CIAT BR 02/1752) cultivado en suelo Ferralítico Rojo Lixiviado. Se evaluaron cuatro tratamientos, tres especies de hongos micorrízicos arbusculares (HMA): Glomus cubense, Funneliformis mosseae y Rizhophagus irregularis, además de un control sin inocular, distribuidos en un diseño cuadrado latino. La inoculación de las diferentes especies de HMA se realizó en el momento de la siembra. Los indicadores evaluados fueron: frecuencia e intensidad de la colonización micorrízica, número de esporas de HMA en la rizosfera, concentraciones de N, P y K en la biomasa, rendimiento de masa seca del pasto y su valor nutritivo, así como el índice de eficiencia y la participación de las cepas de HMA en la nutrición del pasto. Todas las cepas produjeron aumentos significativos en las variables evaluadas; sin embargo, los mayores valores correspondieron a G. cubense, cuyo efecto, a diferencia de las otras, se observó hasta el período poco lluvioso. Esta cepa produjo el mayor índice de eficiencia y tuvo la mayor participación en la nutrición del pasto. Se concluye que la biofertilización con G. cubense puede constituir una práctica agronómica efectiva para mejorar el rendimiento y valor nutritivo del pasto Yacaré cultivado en suelo Ferralítico Rojo Lixiviado. [ABSTRACT FROM AUTHOR]

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Copyright of Revista de Ciencias Agricolas is the property of University of Narino, Faculty of Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Root-knot nematodes (RKN; Meloidogyne spp.), a major plant pathogen of tomato (Lycopersicon esculentum Mill.), causes yield loss in various tomato cultivars. Climatic conditions affect RKN infection; however, the effect of subtropical climate on epidemic RKN that have affected winter tomatoes in China is poorly known. In order to investigate the dynamics of the RKN populations in the rhizosphere soil of winter tomato and to analyze the relationship between grafted and non-grafted tomatoes and their yields, field experiments were conducted at the towns of Shuangqiao and Taiping in Guangxi Province, China during 2014-2016. The experimental fields of early and late sowing tomatoes were located at Shuangqiao and Taiping, respectively. ANOVA and means comparison (Tukey; p£0.05) were performed by using SPSS software version 19.0. Results showed that RKN (Meloidogyne incognita) had three generations in early and late sowing tomatoes. In early sowing tomato at: 0-31, 32-113, and 114-155 d after transplanting (DAT) RKN generations occurred at 31, 81, and 28-42 d respectively. In late sowing tomato, there were three generations at 0-60, 47-101, and 88-157 DAT, nematode needed 46-60, 40, and 55 d to finish each generation. Some nematicides were applied to suppress J2s populations in the fields when the J2 populations peaked. The yield of grafted tomato was significantly higher than that of non-grafted tomato (p£0.05). This result suggested that tolerance to RKN in grafted tomato rootstock was higher than that in non-grafted tomato. [ABSTRACT FROM AUTHOR]

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Copyright of Revista Mexicana de Ciencias Agrícolas is the property of Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Terra Latinoamericana is the property of Sociedad Mexicana de la Ciencia del Suelo A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

La agricultura moderna enfrenta nuevos desafíos, integrando enfoques ecológicos y moleculares, para lograr mayores rendimientos de los cultivos y reducir al mínimo los impactos sobre el ambiente. Para generar mayores rendimientos se han incrementado significativamente las dosis de fertilizantes sintéticos por unidad de superficie, los cuales pueden provocar contaminación, daños a la salud y pérdida de la fertilidad de los suelos, convirtiéndose en una de las preocupaciones más importantes en la producción agrícola. Para mejorar la producción sin el uso de fertilizantes de origen químico, las investigaciones se han orientado hacia el desarrollo de nuevas biotecnologías: provocando que exista un interés creciente en los microorganismos benéficos del suelo ya que éstos pueden promover el crecimiento de las plantas y, en algunos casos, evitar infecciones del tejido vegetal por patógenos. Las interacciones de las rizobacterias promotoras del crecimiento vegetal (RPCV) con el medio biótico – plantas y microorganismos – son muy complejas y utilizan diferentes mecanismos de acción para promover el crecimiento de las plantas. Estos mecanismos se agrupan en: 1) Biofertilización; 2) Fito-estimulación; y 3) Biocontrol. Inocular los cultivos con RPCV reduce sustancialmente el uso de fertilizantes sintéticos y los impactos negativos al suelo, aumenta el rendimiento de los cultivos, contribuyendo a la economía del productor y a la alimentación de la población. Esta revisión describe aspectos básicos inherentes a la interacción entre las RPCV y las especies vegetales, centrándose en los beneficios que aportan las RPCV a la actividad agrícola.

The objective of the present study was to isolate rhizospheric bacteria from samples from the Santa Cruz Mine, department of Bolívar, in order to evaluate in vitro resistance activity at different concentrations of mercury. The samples were collected randomly from different sites near the Santa Cruz gold mine, from which they isolated rhizospheric bacteria. The resistance capacity of bacteria at different concentrations of mercury in the form of mercury chloride (HgCl2) at concentrations of 50 ppm, 100 ppm, 150 ppm, 200 ppm and 250 ppm was evaluated in vitro; also the bacteria resistant to this metal were used to evaluate the ability to promote growth in plants. The results showed that the bacterium identified as Pseudomonas luteola, resisted in vitro at 200 ppm of mercury chloride (HgCl2), and qualitatively had the ability to produce siderophores and biologically fix nitrogen. P luteola was isolated from the rhizosphere near the Santa Cruz mine in the department of Bolívar, Colombia, with soils with high concentrations of mercury and extremely acidic soil reaction.

The present study had as objective to evaluate in vitro the resistance of endophytic bacteria and rizospheric bacteria to different concentrations of Cadmium.This bacteria were isolated fron different tissues of commercial rice varieties and from bacteria isolated from the rhizosphere in rice plantations of the Nechí (Antioquía) and Achí (Bolivar). Plant growth promotion was evaluated in vitro by nitrogen fixation, phosphate solubilization and siderophores production of endophytic bacteria. Of each tissue isolated from rice plants was carried out isolation in culture medium for endophytic bacteria, and the soil samples were serially diluted in peptone water. Each sample was determined the population density by counting in CFU / g of tissue and morphotypes were separated by shape, color, size and appearance in culture media. Significant differences were observed for density population of bacteria with respect to tissue, with higher values in root (4x1011 g/root), followed of the stem (3x1010g/etem), leaf (5x109 g/ leaf), flag leaf (3x109 g/ flag leaf) and with less density in panicle (4x108 g/panicle). The results of the identification with kit API were confirmed the presence of endophytic bacteria Burkholderia cepaceae and rizospheric bacteria Pseudomona fluorescens With the ability to tolerate different concentrations of Cd, fix nitrogen, solubilize phosphates and produce siderophores.

The use of plant growth promoting Rhizobacteria (PGPR) is an alternative to replace chemical fertilizers for the cultivation of agricultural crops. The aim of this research was to search, selection and characterization of PGPR from the genus Azotobacter, Azospirillum and Pseudomonas natives from sweet potato (Ipomoea batatas) plants and rhizosphere of representative production regions of the Colombian Caribbean. Selected isolates were identified by molecular methods and they were screened in vitro for activities related to plant growth such as phosphate solubilization, indole production and acetylene reduction. The strains were tested in the greenhouse on plants of Ipomoea batatas produced in vitro. The height, root length, dry mass of the shot and root were evaluated. Associated with sweet potato crop us finded strains identificated as Azotobacter vinelandii, Azotobacter chroococcum, Azospirillum lipoferum, Azospirillum brasilense and Pseudomonas denitrificans. The strains were able to solubilize phosphate, synthesize indole-3-acetic acid (IAA) and reduce acetylene. The inoculation of bacteria selected increased growth parameters such as root length, height, dry weight root and shoot in plants of sweet potato in greenhouse. Those results catalog to the isolated obtained as possible microorganisms with potential as biofertilizers in sweet potato.

Cerca de la mitad de las tierras continentales del planeta son consideradas áridas o sufren amenaza de sequía. Dentro de las plantas adaptadas a estos ecosistemas destacan los cactus que cuentan con varios mecanismos de adaptación, en particular relacionados a su asociación con comunidades microbianas benéficas a nivel de su rizósfera. Entre ellos destacan las rizobacterias promotoras del crecimiento vegetal (RPCV) y los hongos micorrízicos arbusculares (HMA) conocidos para contribuir al desarrollo exitoso de la planta en condiciones de aridez. La identificación molecular de bacterias y hongos HMA, aislados de la rizósfera de O. ficus-indica de cinco zonas áridas del departamento de Tumbes, ha sido realizada por secuenciación parcial de rDNA. Plantas de cactus cultivadas in vitro han sido establecidas e inoculadas con las cepas microbianas previamente caracterizadas. Ningún efecto morfológico significativo ha sido observado para las plantas inoculadas con las cepas bacterianas mientras que la inoculación de HMA ha conducido en algunos casos a diferencias significativas en el contenido relativo de agua, altura de planta y peso seco de raíz. La presente investigación proporciona información relacionada con la microbiota nativa rizósfera con la demostración de los efectos benéficos de hongos micorrízicos para su planta huésped O. ficus-indica.

Introduction: The sustainable production of pastures has become a fundamental challenge for the livestock sector where research with plant growth-promoting rhizobacteria as a viable solution, has nearly not been reported. Objective: In this study, we aimed to examine the potential to stimulate growth in Pennisetum clandestinum grass using four isolated bacterial strains from soils obtained from a Colombian tropical silvopastoral system. Methods: We previously identified genetically the strains and characterized two plant growth promoting activities. In addition, we evaluated the growth-promoting effect of the strains in Kikuyo grass under greenhouse conditions. Results: We found that the four bacterial strains were phylogenetically associated with Klebsiella sp. (strains 28P and 35P), Beijerinka sp. (37L) and Achromobacter xylosoxidans (E37), based on partial 16S rRNA gene sequencing. Moreover, the in vitro biochemical assays demonstrated that the strains exhibited some plant growth promoting mechanisms such as 1-aminocyclopropane-1-carboxylic acid deaminase activity and indole compound synthesis. Notably, bacterial inoculation under greenhouse conditions showed a positive influence on P. clandestinum growth. We found a significant (P < 0.05) effect on root and shoot length and shoot dry weight. Shoot length increased by 52 % and 30 % with 37L and 35P compared to those without inoculation treatment. Similarly, the use of 37L and 28P raised shoot dry weight values by 170 % and 131 %, respectively. In root development, inoculation with strains 37L and E37 increased root length by 134 % and 100 %, respectively. Conclusion: Beijerinckia sp. 37L was the most effective of the four strains at increasing P. clandestinum biomass and length. [ABSTRACT FROM AUTHOR]

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Phosphorus plays a fundamental role in plant metabolic processes. Lack of phosphorus in agricultural soils is compensated with chemical fertilizers, which increase the cost of production and contaminate the environment. One approach to avoid this situation is the use of P-solubilizing fungi as biofertilizers. In this study, the solubilization of Ca3(PO4)2 by five native soil-borne micromycetes (SBM) isolated from the rhizosphere of Carica papaya plants was evaluated. The significant nutritional factors involved in the solubilization of Ca3(PO4)2 by Penicillium hispanicum were determined through a Plackett-Burman experimental design (PBED). Both Penicillium SP1 (108.5 mg/L) and P. hispanicum (106.5 mg/L) solubilized 100% of Ca3(PO4)2 at six days of culture. All studied SBM decreased the pH of the culture medium from 4.15 (control) to <2.45. The PBED revealed that the solubilization of Ca3(PO4)2 by P. hispanicum was significantly influenced (P < 0.05) by low values of MnSO4 (0.002 g/L), (NH4)2SO4 (0.25 g/L) and pH (4.0) and a high amount of Ca3(PO4)2 (0.75 g/L). Total protein content was influenced significantly (P <0.05) by low amounts of glucose (5.0 g/L), yeast extract (0.25 g/L), inoculum (1x105 conidia/mL) and pH (4.0) and high amounts of MgSO4 (0.15 g/L), FeSO4 (0.003 g/L) and Ca3(PO4)2 (0.75 g/L). Meanwhile, biomass production was significantly (P < 0.05) influenced by a high level of glucose (15.0 g/L) and inoculum amount (1x107 conidia/mL). In conclusion, P. hispanicum is a good candidate for further field experiments to test Ca3(PO4)2 solubilization in poor soils that lack C and N sources. [ABSTRACT FROM AUTHOR]