Ceratocystis fimbriata agente causal de la enfermedad de marchitez vascular de Tectona grandis L.f. (teca) en Ecuador / Ceratocystis fimbriata causative agent of vascular wilt disease of Tectona grandis L.f. (teak) in Ecuador

Tectona grandis L.f. es una especie forestal de madera dura que, a pesar de no ser nativa de América, su plasticidad de adaptación ha permitido que en Ecuador se establezcan plantaciones intensivas con fines de exportación. Una compleja enfermedad con características de marchitez vascular está matando miles de árboles de diferentes edades en el país. Se planteó conocer el agente fitopatógeno causante de la patogénesis y muerte de los árboles. Se aislaron los hongos Fusarium sp. y Ceratocystis fimbriata Ellis & Halst. desde árboles enfermos. A nivel de invernadero se plantearon los postulados de Koch, para el efecto 30 plantas de T. grandis de cuatro meses de edad por cada tratamiento, se inocularon con los microrganismos como se describe a continuación: T1= C. fimbriata, T2 = Fusarium sp., T3 = C. fimbriata + Fusarium sp., T4 = agar-agar (control). Se empleó un diseño completo al azar (DCA) y las plantas se evaluaron a los 45 días después de inoculadas. Los tratamientos C. fimbriata, y C. fimbriata + Fusarium sp., mostraron mayores volúmenes aparentes de necrosis, con 1.52 cm3 y 1.93 cm3, y plantas muertas por la infección durante el tiempo de evaluación, mientras que Fusarium sp. mostró baja o nula patogenicidad y comportamiento similar al control, con 0.27 cm3 y 0.16 cm3 respectivamente. Estos resultados sugieren que el agente causal de la enfermedad de marchitez vascular en T. grandis es C. fimbriata y sería el primer reporte del fitopatógeno atacando teca en Ecuador. (AU)

Tectona grandisL.f. it is a hardwood forest species, which despite not being native to America, its adaptive plasticity has allowed intensive plantations to be established for export purposes in Ecuador. A complex disease with characteristics of vascular wilt is killing thousands of trees of different ages in the country. It was proposed to know the phytopathogenic agent causing the pathogenesis and death of the trees. Fusarium sp. andCeratocystis fimbriata Ellis & Halst. were isolated from diseased trees. At the greenhouselevel, Koch's postulates were proposed, for the effect 30 four month old T. grandisplants for each treatment were inoculated with the microorganisms as described below: T1 = C. fimbriata, T2 = Fusariumsp ., T3 = C. fimbriata+ Fusariumsp., T4 = agar-agar (control). A complete randomized design (DCA) was used and the plants were evaluated 45 days after inoculation. The treatments C. fimbriata, and C. fimbriata+ Fusariumsp. showed higher apparent volumes of necrosis, with 1.52 cm3and 1.93 cm3, and plants killed by the infection during the evaluation time, while Fusariumsp. showed low or no pathogenicity and behavior similar to the control, with 0.27 cm3and 0.16 cm3respectively. These results suggest that the causative agent of vascular wilt disease in T. grandisis C. fimbriataand it would be the first report of phytopathogen attacking teak in Ecuador. (AU)

Hongos fitopatógenos asociados a la enfermedad de marchitez vascular y muerte regresiva en plantaciones de Tectona grandis L. f. (teca) en el Trópico Húmedo Ecuatoriano / Phytopathogen fungi related to vascular wilt and die back in Tectona grandis L. f (teak) field in Ecuadorian Tropical Rainforest

Plantaciones de teca (Tectona grandis L.f.) en Ecuador están siendo afectadas por una compleja enfermedad de marchitez vascular y muerte regresiva, con características epidémicas, sin que hasta el momento se conozca el o los agentes causales. Se planteó describir la sintomatología de la enfermedad e identificar los hongos fitopatógenos asociados a árboles enfermos en el Trópico Húmedo Ecuatoriano mediante morfofisiología. Se seleccionaron tres plantaciones de 2, 5 y 7 años de edad, en cada una se delimitó tres parcelas de 500 m2. Se realizó la descripción sintomatológica, evaluó la incidencia y severidad de la enfermedad empleando una escala de cinco categorías. Por parcela se diseccionaron tres árboles, cuyos tejidos se llevaron al laboratorio, donde se emplearon tres estrategias metodológicas (cámara húmeda, sandwiches de zanahoria, y medio de cultivo papa-dextrosa-agar; PDA) para estimular la expresión de los fitopatógenos. En árboles enfermos se detectó clorosis, pérdida de turgencia, ápices de crecimiento secos, emisión de brotes epicormicos en el fuste, y marchitez fulminante. Se aisló e identificó Ceratocystis fimbriata Ellis & Halst., y especies de Fusarium de forma consecutiva con las tres estrategias metodológicas empleadas. La incidencia de la enfermedad fue del 16.6%, 15.2%, y 11.6% para las plantaciones de 2, 5 y 7 años, respectivamente. Los árboles enfermos en la plantación de 2 años se encontraron en las escalas 2, 4 y 5, mientras que en plantaciones de 5 y 7 años se ubicaron en las escalas 2, 3 y 5 de progreso de la enfermedad...(AU)

Teak plantations (Tectona grandis L. f.) in Ecuador are being affected by a complex disease of vascular wilt and dieback, with epidemic characteristics, without knowing the causal agent(s) so far. We proposed to describe the symptomatology of the disease and identify phytopathogenic fungi associated with diseased trees in the Ecuadorian Humid Tropic by morphophysiology. Three plantations of 2, 5 and 7 years of age were selected, in each three plots of 500 m2 were delimited. The symptomatologic description was made, evaluated the incidence and severity of the disease using a scale of five categories. By plot, three trees were dissected, whose tissues were taken to the laboratory, where three methodological strategies were used (wet chamber, carrot sandwiches, and potatodextrose-agar culture medium, PDA) to stimulate the expression of phytopathogens. In diseased trees, chlorosis, turgor loss, dry growth apices, emission of epicormic shoots in the stem, and fulminating wilt were detected. It was isolated and identified Ceratocystis fimbriata Ellis & Halst., and Fusarium species. consecutively with the three methodological strategies employed. The incidence of the disease was 16.6%, 15.2%, and 11.6% for plantations of 2, 5 and 7 years, respectively. The sick trees in the plantation of 2 years were found in scales 2, 4 and 5, while in plantations of 5 and 7 years they were located in scales 2, 3 and 5 of progress of the disease. ..(AU)

Mangrove endophyte promotes reforestation tree (Acacia polyphylla) growth

ABSTRACT Mangroves are ecosystems located in the transition zone between land and sea that serve as a potential source of biotechnological resources. Brazil's extensive coast contains one of the largest mangrove forests in the world (encompassing an area of 25,000 km2 along all the coast). Endophytic bacteria were isolated from the following three plant species: Rhizophora mangle, Laguncularia racemosa and Avicennia nitida. A large number of these isolates, 115 in total, were evaluated for their ability to fix nitrogen and solubilize phosphorous. Bacteria that tested positive for both of these tests were examined further to determine their level of indole acetic acid production. Two strains with high indole acetic acid production were selected for use as inoculants for reforestation trees, and then the growth of the plants was evaluated under field conditions. The bacterium Pseudomonas fluorescens (strain MCR1.10) had a low phosphorus solubilization index, while this index was higher in the other strain used, Enterobacter sp. (strain MCR1.48). We used the reforestation tree Acacia polyphylla. The results indicate that inoculation with the MCR1.48 endophyte increases Acacia polyphylla shoot dry mass, demonstrating that this strain effectively promotes the plant's growth and fitness, which can be used in the seedling production of this tree. Therefore, we successfully screened the biotechnological potential of endophyte isolates from mangrove, with a focus on plant growth promotion, and selected a strain able to provide limited nutrients and hormones for in plant growth.

Natural decomposition of hornbeam wood decayed by the white rot fungus Trametes versicolor

ABSTRACT The impacts of white-rot fungi on altering wood chemistry have been studied mostly in vitro. However, in vivo approaches may enable better assessment of the nature of interactions between saprotrophic fungi and host tree in nature. Hence, decayed and sound wood samples were collected from a naturally infected tree (Carpinus betulus L.). Fruiting bodies of the white rot fungus Trametes versicolor grown on the same tree were identified using rDNA ITS sequencing. Chemical compositions (cellulose and lignin) of both sound and infected wood were studied. FT-IR spectroscopy was used to collect spectra of decayed and un-decayed wood samples. The results of chemical compositions indicated that T. versicolor reduced cellulose and lignin in similar quantities. Fungal activities in decayed wood causes serious decline in pH content. The amount of alcohol-benzene soluble extractives was severely decreased, while a remarkable increase was found in 1% sodium hydroxide soluble and hot water extractive contents in the decayed wood samples, respectively. FT-IR analyses demonstrated that T. versicolor causes simultaneous white rot in the hornbeam tree in vivo which is in line with in vitro experiments.

Illumina-based analysis of endophytic bacterial diversity of tree peony (Paeonia Sect. Moutan) roots and leaves

ABSTRACT Diverse communities of bacteria inhabit plant tissues and those bacteria play a crucial role for plant health and growth. Tree peony (Paeonia Sect. Moutan) is known for its excellent ornamental and medicinal values as Chinese traditional plant, but little is known about its associated bacterial community under natural conditions. To examine how endophytic bacteria in tree peony vary across tissues and cultivars, PCR-based Illumina was applied to reveal the diversity of endophytic bacteria in tree peony. A total of 149,842 sequences and 21,463 operational taxonomic units (OTUs) were obtained. The OTU abundance of roots was higher than leaves across other three cultivars except for 'Kinkaku' and 'Luoyanghong'. The community was composed of five dominant groups (Proteobacteria, Firmicutes, Bacteroidetes, Acidobacteria and Actinobacteria) in all samples. Endophytic bacteria community structures had changed in leaves and roots. Sequences of Pseudomonas and Enterobacteriaceae were prevalent in root samples, whereas Succinivibrio and Acinetobacter were the dominant genus in leaf samples. Otherwise, the distribution of each dominant genus among the 5 cultivars was either varied. These findings suggested that both plant genotype and tissues contribute to the shaping of the bacterial communities associated with tree peony.

Aislamiento presuntivo y caracterización de cryptococcus neoformans y cryptococcus gattii desde árboles en la región de O’Higgins y Maule, Chile / Presumptive isolation and characterization of cryptococcus neoformans and cryptococcus gattii from trees in the region of O’Higgins and Maule, Chile

Introducción: la criptocococis es una micosis sistémica causada por C. neoformans y C. gattii, es frecuente y oportunista en inmunocomprometidos y patógeno primario en personas inmunocompetentes. C. neoformans tiene una distribución mundial y se ha aislado desde las excretas de palomas. C. gattii se considera restringida a regiones con clima tropical, subtropical, y templadas, se encuentra asociada frecuentemente a detritos de especies de Eucalyptus sp. La virulencia de estas levaduras le permite desarrollar patogénesis en mamíferos y supervivencia en el ambiente. Objetivo: Identificar y determinar la actividad de proteinasas y fosfolipasas, de C. neoformans y C. gattii aisladas desde las oquedades de árboles en lugares con alta afluencia de público. Materiales y Métodos: Se tomaron 200 muestras de hisopado desde distintas especies de árboles desde sectores de la región de O’Higgins y el Maule. Se siembran en ASG, se aíslan y mantienen en ASD. Identificación con tinta china, Urea de Christensen, crecimiento a 37°C, asimilación y fermentación de azucares, y siembra en medio CGB. Se mide índice de actividad enzimática Prz de proteinasas y fofolipasas. Resultados y Conclusiones: Se obtuvieron 109 cepas de C. neoformans aisladas desde las oquedades de diferentes especies arbóreas y 3 cepas presuntivas de C. gattii desde Eucalyptus sp. y Prunus cerasifera artropurpurea. El 88,1 por ciento de las cepas C. neoformans y 100 por ciento de C. gattii, presentaron alta actividad proteolítica, El 49,5 por ciento de las cepas de C. neoformans y 33,3 por ciento de C. gattii mostraron alta actividad de fosfolipasas.

Introduction: criptocococis is a systemic mycosis caused by C. neoformans and C. gattii, frequent and opportunistic in immunocompromised and primary pathogen in immunocompetent persons. C. neoformans has a worldwide distribution and has been isolated from the excreta of pigeons. C. gattii is considered restricted to regions with tropical, subtropical, and temperate, is often associated with species of Eucalyptus sp. The virulence of these yeasts develop pathogenesis allows survival in mammals and the environment. Objective: To identify and determine the activity of proteinases and phospholipases of C. neoformans and C. gattii isolated from the hollows of trees in places with high turnout. Materials and Methods: 200 swab samples were taken from different species of trees from areas of the region of O’Higgins and Maule. Planted in ASG, they are isolated and kept in ASD. Identification with ink, Urea Christensen, growth at 37 ° C, assimilation and fermentation of sugars, and planting medium CGB. Prz index proteinase enzyme activity is measured and phospholipases. Results and Conclusions: We manage to get 109 strains of C. neoformans isolated from the hollows of different tree species and 3 presumptive strains of C. gattii from Eucalyptus sp. and Prunus cerasifera artropurpurea. 88.1 percent of the strains C. neoformans and C. gattii 100 percent , they showed high proteolytic activity, 49.5 percent of the strains of C. neoformans and C. gattii 33.3 percent showed high activity phospholipases.

Ciclo de vida de corynelia tropica, patógeno foliar en podocarpus saligna / Life cycle of corynelia tropica, leaf pathogen on podocarpus saligna

El presente estudio tuvo como objetivo determinar el ciclo de vida de Corynelia tropica, patógeno de hojas y ramillas en mañío de hoja larga (Podocarpus saligna). Mensualmente se recolectaron ramillas de P. saligna. En la medida que se fueron detectando estadíos interesantes dentro del ciclo de vida de este patógeno, la frecuencia de las colectas se intensificó en forma quincenal, e incluso semanal. Se pudo constatar que C. tropica presentó un ciclo de vida anual muy definido, con gran regularidad en la aparición y desarrollo de sus estructuras fructíferas. Invariablemente el ciclo de vida se inició en la primera quincena de noviembre con la inoculación de los nuevos brotes de P. saligna. A inicios de enero se manifestaron los primeros síntomas de la infección y a comienzos de marzo ya eran notorias las estructuras del anamorfo. A fines de mayo las estructuras del teleomorfo se hacían protuberantes y se iniciaba la formación de los ascos. A fines de julio los ascocarpos presentaban forma y tamaño ya adulto, y las ascosporas al interior de los ascos se encontraban en proceso de maduración. A fines de octubre las ascosporas ya estaban maduras y su liberación a comienzos de noviembre, sincronizaba con la emergencia de los brotes de P. saligna, con lo que se daba inicio una vez más a un nuevo ciclo de vida de C. tropica. Se pudo constatar que además del follaje y ramas, este patógeno también atacaba a los frutos de P.saligna.

This study aimed to determine the life cycle of Corynelia tropica, pathogen leaves and twins in longleaf mañío (Podocarpus saligna). Monthly P. saligna twigs were collected. As they were detecting interesting stages in the life cycle of this pathogen, the frequency of collections were intensified fortnightly or even weekly. It was found that C. tropica presented a very defined, with great regularity in the occurrence and development of their fruiting structures annual life cycle. Invariably the life cycle began in the first half of November with the inoculation of new outbreaks of P. saligna. In early January the first symptoms of infections manifested and early March were already notorious the anamorph structure. In late May teleomorph structures became prominent and the formation of the asci began. In late July the ascocarps presented adult size and shape, and the ascospores within the asci were maturing. In late October ascospores were ripe and in early November, release synchronized with outbreaks of P. saligna, which was given start again a new life cycle of C. tropica. It was found that besides the foliage and branches, this pathogen also attacked the fruits of P. saligna.

Characterization saprobic fungi on leaf litter of two species of trees in the Atlantic Forest, Brazil

Abstract We investigated the composition and structure of fungal communities associated with leaf litter generated by Clusia nemorosa and Vismia guianensis that belong to phylogenetically-related botanical families and exist together in a remnant of the Atlantic Forest in Bahia, Brazil. Samplings were conducted during wet (June 2011) and dry (January 2013) seasons in Serra da Jibóia. The fungi were isolated using particle filtration and the 1,832 isolates represented 92 taxa. The wet season yielded the largest number of isolates (1,141) and taxa (76) compared with the dry season (641 isolates and 37 taxa). The richness and diversity of fungal species associated with C. nemorosa (64 taxa, Simpson=0.95)were higher compared with those of V.guianensis (59 taxa, Simpson =0.90). Analysis of similarity (ANOSIM) revealed significant variations in the composition and community structure of fungi isolated from the two plants as a function of seasons. In contrast, nonmetric multidimensional scaling (NMDS) analysis show that the seasonality was an important influence on the distribution of fungal species. However, the populations of the saprobic fungal communities were dynamic, and several factors may influence such communities in the Atlantic Forest.

Identificación de microorganismos del género phytophthora asociados a especies de Quercus sp. y Pinus sp., en los departamentos de Guatemala y Sacatepéquez / Identification of microorganisms of phytophthora genre associated to Quercus sp. and Pinus sp. species in the provinces of Guatemala and Sacatepéquez

El objetivo principal fue la identificación de microorganismos del género Phytophthora que afectan a bosques naturales mixtos y viveros de Pinus sp. y Quercus sp., con importancia socioeconómica, en los departamentos de Guatemala y Sacatepéquez. Para el aislamiento de Phytophthora se procesaron muestras de suelo y tejido vegetal. En el departamento de Guatemala, del bosque natural se obtuvieron 10 muestras de Quercus sp. y 45 de Pinus sp., de los viveros se obtuvieron 11 muestras de Quercus sp. y 88 de Pinus sp. En el departamento de Sacatepéquez se obtuvieron del bosque natural 15 muestras de Quercus sp. y 48 de Pinus sp.; y en los viveros, 58 muestras de Pinus sp. y 25 de Quercus sp. Un total de 13 muestras procedentes de los viveros fueron positivas a la presencia de Phytophthora sp. en Pinus maximinoi, 10 procedentes del departamento de Guatemala, y tres de Sacatepéquez. Referente al tipo de crecimiento de la colonia en medio PDA, se obtuvieron cinco de tipo estolonífero, cinco tipo semipetaloide, una colonia de tipo estelado y dos colonias sin ningún tipo de patrón de crecimiento. Las pruebas de patogenicidad realizadas con la cepa VP16 mostraron alta incidencia y severidad para las especies de Pinus caribaea, P. oocarpa, P. pseudostrobus, P. maximinoi y en menor grado en Pinus tecunumanii.

The mean purpose of this research was to identify microorganism belonging to Phytophthora genera which are affecting mixed natural forests and nurseries of Pinus sp. and Quercus sp. These species have economic and social impact in provinces such as Guatemala and Sacatepéquez. Soil and vegetal tissue were used to isolate Phytophthora from natural forest of Guatemala, 45 Pinus sp. and 10 Quercus sp. were sampled and from nurseries 88 Pinus sp. and 11 Quercus sp. From Sacatepéquez province, from natural forest system were sampled 48 Pinus sp. and 15 Quercus sp. From nurseries were sampled 58 Pinus sp. and 25 Quercus sp. After processing the samples from soil and roots 13 were found positive to Phytophthora sp. in Pinus maximinoi, 10 from Guatemala and three from Sacatepéquez Provinces. The culture of Phytophthora sp. on PDA produced two colonies without define form and five stoloniferous, five semipetaloid, one stelade type colonies. VP16 isolate was inoculated in five species of pine for pathogenicity test, causing high percentages of incidence and severity on Pinus caribaea, P. oocarpa, P. pseudostrobus and P. maximinoi and low rates of incidence and severity on Pinus tecunumanii.

Morphology and mycelial growth rate of Pleurotus spp. strains from the Mexican mixtec region

Two native Pleurotus spp. strains (white LB-050 and pale pink LB-051) were isolated from rotten tree trunks of cazahuate (Ipomoea murucoides) from the Mexican Mixtec Region. Both strains were chemically dedikaryotized to obtain their symmetrical monokaryotic components (neohaplonts). This was achieved employing homogenization time periods from 60 to 65 s, and 3 day incubation at 28 °C in a peptone-glucose solution (PGS). Pairing of compatible neohaplonts resulted in 56 hybrid strains which were classified into the four following hybrid types: (R1-n xB1-n, R1-n xB2-1, R2-n xB1-n and R2-n xB2-1). The mycelial growth of Pleurotus spp. monokaryotic and dikaryotic strains showed differences in texture (cottony or floccose), growth (scarce, regular or abundant), density (high, regular or low), and pigmentation (off-white, white or pale pink). To determine the rate and the amount of mycelium growth in malt extract agar at 28 °C, the diameter of the colony was measured every 24 h until the Petri dish was completely colonized. A linear model had the best fit to the mycelial growth kinetics. A direct relationship between mycelial morphology and growth rate was observed. Cottony mycelium presented significantly higher growth rates (p < 0.01) in comparison with floccose mycelium. Thus, mycelial morphology can be used as criterion to select which pairs must be used for optimizing compatible-mating studies. Hybrids resulting from cottony neohaplonts maintained the characteristically high growth rates of their parental strains with the hybrid R1-n xB1-n being faster than the latter.

Phenotypic plasticity of the basidiomata of Thelephora sp. (Thelephoraceae) in tropical forest habitats

Phenotypic plasticity in macroscopic fungi has been poorly studied in comparison to plants or animals and only general aspects of these changes have been described. In this work, the phenotypic variation in the basidiomata of Thelephora sp. (Thelephoraceae) was examined, as well as some aspects of its ecology and habitat, using 24 specimens collected in the tropical forests of the Chamela Biological Station, Jalisco, Mexico. Our observations showed that this taxon has clavarioid basidiomata that can become resupinate during development and growth if they are in contact with rocks, litter or live plants, establishing in the latter only an epiphytic relationship. This tropical species may form groups of up to 139 basidiomata over an area of 32.2m2, and in both types of vegetation (tropical sub-evergreen and deciduous forest) were primarily located on steep (>20°) South-facing slopes. It is found under closed canopy in both tropical forests, but its presence in sub-evergreen forests is greater than expected.

La plasticidad fenotípica en hongos macroscópicos ha sido poco estudiada en comparación con la de plantas o animales y solo se conocen aspectos generales de estos cambios. En este trabajo se examinó la variación fenotípica en los basidiomas de una especie de Thelephora sp. (Thelephoraceae), así como algunos aspectos de su ecología y hábitat a partir del estudio de 24 ejemplares recolectados en bosques tropicales de la Estación de Biología de Chamela, Jalisco, México. Nuestras observaciones mostraron que este taxon presenta basidiomas en forma clavarioide, los cuales pueden modificarse a resupinados si en su proceso de desarrollo se interponen obstrucciones físicas como rocas, restos vegetales o plantas vivas, estableciendo en estas últimas solo una relación epifítica. Esta especie llega a formar conjuntos de hasta 139 basidiomas en un área de 32.2m2; con localización predominante en laderas orientadas hacia el sur, de pendientes mayores a 20°, bajo doseles cerrados y con presencia mucho más significativa de lo esperado en el bosque tropical subperennifolio.

Variación espacial y estacional de grupos funcionales de bacterias cultivables del suelo de un bosque tropical seco en México / Spatial and seasonal variation of soil culturable-bacterial functional groups in a Mexican tropical dry forest

Microbial biomass and activity in soils are frequently studied in tropical dry forests, but scarce information is available about the relationships between functional bacterial groups and soil fertility, where relief interacts with rainfall seasonality. The culturable-bacterial groups and nutrients were studied during two consecutive years in soils from two topographic areas of different relief (hilltop vs hillslope) in a tropical dry forest from Chamela Jalisco, Mexico. We expected that seasonal and spatial variation in soil resources availability affects the abundance of functional culturable-bacterial groups. To evaluate this, fifteen soil cores (1kg), 0-5cm depth, were taken in the dry, early rainy and rainy seasons, from each of the ten replicate plots in hilltop and hillslope areas located in three microbasins. We found that hilltop soils were more organic and had higher concentration of labile C and total nutrient forms than hillslope soils, for which these soils had higher counts of colony-forming units (CFU) of total heterotrophic and P solubilizing bacteria. In both hilltop and hillslope soils, C and nutrient concentrations, as well as the counts of CFU of heterotrophic and P solubilizing bacteria generally decreased from the dry to the rainy season during the two study years. In contrast, the counts of CFU nitrifying and cellulolytic bacteria were higher at the hillslope than at the hilltop soils. The seasonal pattern of both groups was opposite to that of heterotrophic bacteria, presumably associated with a decrease in soil labile C and organic matter quality. In conclusion, our study suggests that available C appears to be the main factor that controls the structure of soil bacterial groups and soil fertility, where relief, rainfall seasonality and intraand inter-annual variations are critical factors that interactively modify bacterial dynamics related to soil C availability in the tropical dry forest.

Los bosques tropicales secos tienen una amplia heterogeneidad ambiental y por lo tanto se podría esperar una variación temporal y espacial en la abundancia y tipo de grupos bacterianos activos. Se evaluó, durante dos años consecutivos, el efecto de la estacionalidad de la lluvia sobre algunos grupos bacterianos cultivables y nutrimentos del suelo en dos posiciones topográficas (crestas vs laderas) en el bosque tropical seco, Chamela Jalisco, México. La hipótesis fue que la variación temporal y espacial de la disponibilidad de recursos afectaría la abundancia de los grupos bacterianos funcionales (heterótrofas totales, celulolíticas, solubilizadores de fosfatos y nitrificantes) del suelo. En las crestas, el suelo fue más orgánico y con mayor concentración de nutrimentos totales y C orgánico lábil que en la ladera, registrando más bacterias heterótrofas y solubilizadoras de fosfato. En ambas posiciones topográficas la concentración de C y nutrimentos, así como el número de bacterias heterótrofas y solubilizadoras de P, decrecieron de la estación seca a la lluviosa en ambos años. En contraste, las bacterias nitrificantes fueron mayores en el suelo de la ladera, y al igual que las celulolíticas, tuvieron un patrón estacional opuesto a las bacterias heterótrofas, asociado a la disminución del C lábil y de la calidad de la materia orgánica. En conclusión, se sugiere que el relieve, la estacionalidad y la variación inter-anual de la lluvia regulan interactivamente la relación entre el C disponible y la estructura de las comunidades bacterianas del suelo en el bosque tropical seco de Chamela.

Cultivable bacterial diversity along the altitudinal zonation and vegetation range of tropical Eastern Himalaya

The Northeastern part of India sprawls over an area of 262 379km² in the Eastern Himalayan range. This constitutes a biodiversity hotspot with high levels of biodiversity and endemism; unfortunately, is also a poorly known area, especially on its microbial diversity. In this study, we assessed cultivable soil bacterial diversity and distribution from lowlands to highlands (34 to 3 990m.a.s.l.). Soil physico-chemical parameters and forest types across the different altitudes were characterized and correlated with bacterial distribution and diversity. Microbes from the soil samples were grown in Nutrient, Muller Hinton and Luria-Bertani agar plates and were initially characterized using biochemical methods. Parameters like dehydrogenase and urease activities, temperature, moisture content, pH, carbon content, bulk density of the sampled soil were measured for each site. Representative isolates were also subjected to 16S rDNA sequence analysis. A total of 155 cultivable bacterial isolates were characterized which were analyzed for richness, evenness and diversity indices. The tropical and sub-tropical forests supported higher bacterial diversity compared to temperate pine, temperate conifer, and sub-alpine rhododendron forests. The 16S rRNA phylogenetic analysis revealed that Firmicutes was the most common group followed by Proteobacteria and Bacteroidetes. Species belonging to the genera Bacillus and Pseudomonas were the most abundant. Bacterial CFU showed positive but insignificant correlation with soil parameters like pH (r=0.208), soil temperature (r=0.303), ambient temperature (r=0.443), soil carbon content (r=0.525), soil bulk density (r=0.268), soil urease (r=0.549) and soil dehydrogenase (r=0.492). Altitude (r=0.561) and soil moisture content (r=-0.051) showed negative correlation. Altitudinal gradient along with the vegetation and soil physico-chemical parameters were found to influence bacterial diversity and distribution. This study points out that this is a biome with a vast reservoir of bacteria which decrease with increasing altitudes, and highlights the microbiological importance of the poorly studied Eastern Himalayan range, justifying efforts to explore the prevalence of novel species in the biome.

La parte noreste de la India se extiende sobre una superficie de 262 379km² en la cordillera oriental del Himalaya. Es un punto de acceso con altos niveles de biodiversidad y endemismo; desafortunadamente, también es una zona poco conocida, sobre todo su diversidad microbiana. En este estudio se evaluó la diversidad de bacterias cultivables del suelo, su diversidad y distribución de las tierras bajas a las altas (34 a 3 990m.s.n.m). Se caracterizaron los parámetros físico-químicos del suelo y tipos de bosques a lo largo del gradiente altitudinal y se correlacionaron con la distribución y diversidad bacteriana. Los microbios del suelo se cultivaron en placas de agar enriquecido Muller Hinton y Luria-Bertani, e inicialmente se caracterizaron mediante métodos bioquímicos. Parámetros tales como actividad de la deshidrogenasa y ureasa, temperatura, contenido de humedad y de carbono, pH y densidad aparente del suelo se midieron en cada sitio. Aislamientos representativos también se sometieron al análisis secuencial de 16S rADN. Un total de 155 aislamientos bacterianos cultivables se caracterizaron para estimar los índices de riqueza, equidad y diversidad. Los bosques tropicales y subtropicales albergan una mayor diversidad bacteriana en comparación con los bosques templados de pino y coníferas, y los bosques subalpinos de rododendro. El análisis filogenético de 16S rARN reveló que Firmicutes fue el grupo más común, seguido de Proteobacteria y Bacteroidetes. Especies pertenecientes a los géneros Bacillus y Pseudomonas fueron las más abundantes. Las UFC bacterianas mostraron una positiva pero insignificante correlación con los parámetros del suelo, tales como pH (r=0.208), temperatura (r=0.303), temperatura ambiente (r=0.443), contenido de carbón (r=0.525), densidad aparente (r=0.268), ureasa (r=0.549) y deshidrogenasa (r=0.492). La altitud (r=-0.561) y el contenido de humedad del suelo (r=-0.051) mostraron una correlación negativa. Se encontró que el gradiente altitudinal, junto con la vegetación y los parámetros físico-químicos influyeron en la diversidad bacteriana y la distribución. Este estudio señala que este es un bioma con un vasto reservorio de bacterias que disminuyen con la altitud y pone en relieve la importancia microbiológica de la pobremente estudiada zona del este del Himalaya, lo que justifica los esfuerzos para explorar la prevalencia de nuevas especies en el bioma.

Propuesta de un método para evaluar resistencia genética en Schizolobium parahybum (Vell) Blake (Pachaco) frente a Ceratocystis spp: evidencias preliminares de resistencia en Ecuador / Proposal for a method to evaluate genetic resistance in Schizolobium parahybum (Vell) Blake (Pachaco) against ceratocystis spp: preliminary evidence of resistance in Ecuador

Se condujo una investigación en el Trópico Húmedo Ecuatoriano (THE), dirigida a encontrar un método eficiente para evaluar la resistencia genética en árboles de Schizolobium parahybum (pachaco) frente al complejo Ceratocystis: C. paradoxa, C. moniliformis, y C. fimbriata. Se estudiaron dos métodos basados en el empleo de dos tipos de tejidos vegetales: a) tejidos de ramas laterales, y 2) tejidos de corteza fustal. Se emplearon cinco rodales de pachaco, tres de los cuales son considerados de introducción original de la especie forestal al THE desde la amazonía, y dos que son descendientes de los primeros. Los resultados permitieron definir que el método basado en tejidos de corteza fustal, fue el más eficiente y logísticamente viable. La metodología final aplicada, consistió en extraer corteza desde árboles adultos, reducirla a secciones pequeñas de 1,5 cm x 4 cm (6 cm2) y mantenerlas en una cámara húmeda durante 96 horas. Una vez distribuidas las secciones de corteza, se inocularon con 0,45mL-1 de una suspensión calibrada a razón de 30.000 unidades de infección (ascosporas, conidias y micelio). Para la evaluación, se empleó una escala arbitraria de 0 a 4 que permitió estimar el crecimiento de micelio y número de peritecios para cada uno de los hongos. Esta metodología permitió discriminar entre árboles: resistentes (0,0 a 1,0), moderadamente resistentes (1,1 a 2,0), susceptibles (2,1 a 3,0), y muy susceptibles (3,1 a 4,0), lo cual la hace viable para futuros trabajos de selección de individuos y mejoramiento genético de la especie.

A research was conducted in the Humid Tropics of Ecuador (THE), aimed at finding an efficient method to evaluate genetic resistance in Schizolobium parahybum (Pachaco) trees against Ceratocystis complex: C. paradoxa, C. moniliformis and C. fimbriata. We studied two methods based on the use of two types of plant tissues: a) tissue of lateral branches, and 2) stem bark tissues. Five forest of pachaco were used, three of which are considered original introduction of forestry specie to THE from the Amazon, and two who are descendants of the former. The results allowed to define the method based on stem bark tissue was the most efficient and logistically feasible. The final methodology applied, consisted in to remove bark from mature trees, reducing it to small sections of 1.5 cm x 4 cm (6cm2) and maintained in a moist chamber for 96 hours. Once distributed the sections of bark, were inoculated with 0.45mL-1 of a suspension calibrated at a rate of 30.000 units of infection (ascospores, conidia and mycelium). For evaluation, we used an arbitrary scale from 0 to 4, which allowed to estimate the growth of mycelium and perithecia number for each of the fungi. This methodology allows us to discriminate between trees: resistant (0.0 to 1.0), moderately resistant (1.1 to 2.0), susceptible (2.1 to 3.0), and very susceptible (3.1 to 4 , 0), which makes it viable for future selection of individuals and breeding of the forest species.

Hongos fitopatógenos asociados a la enfermedad de muerte regresiva y pudrición del fuste de Pachaco (Schizolobium parahybum) en el trópico húmedo ecuatoriano / Fungi pathogens associated disease dieback and stem rot of Pachaco (Schizolobium parahybum) in the Ecuadorian humed tropics

La enfermedad de muerte regresiva y pudrición del fuste de Pachaco (Schizolobium parahybum Vell Blake) fue detectada inicialmente 1988, matando árboles jóvenes en la zona central del Trópico Húmedo Ecuatoriano, desde entonces, cada año, miles de árboles mueren por esta causa. En el año 2002 se realizó la presente investigación que abarcó tres rodales de distintas edades, ubicados en provincias diferentes, planteándose los siguientes objetivos: describir la sintomatología de la enfermedad, su incidencia en las zonas de estudio e identificar los microorganismos asociados a árboles de S. parahybum enfermos. La enfermedad mostró una sintomatología compleja, empezando con una marchitez vascular y perdida de coloración verde oscura de las hojas hasta tornarse cloróticas. Las heridas no cicatrizadas mostraron una pudrición circular que afecta la corteza y el xilema, emanando fluidos de color amarillo claro a café oscuro, con fuerte olor a materia orgánica en descomposición. En la provincia de Los Ríos (rodal mayor a 25 años) se encontró la mayor incidencia de la enfermedad (55 por ciento), seguido de las provincias Esmeraldas (rodal de 8 años) y Santo Domingo de Los Tsáchilas (rodal de 4 años) con 29 y 24 por ciento, respectivamente. De árboles enfermos se aislaron e identificaron cinco hongos, tres a nivel de género: Macrophoma sp., Fusarium sp. y Graphium sp. y dos a nivel de especies: Ceratocystis paradoxa (Dade) y C. moniliformis (Hedgc.). Las pruebas de patogenicidad demostraron que C. paradoxa, Macrophoma sp. y C. moniliformis provocaron los mayores valores de volumen aparente de necrosis con 5.40, 3.55 y 3.48 cm3respectivamente.

Dieback disease and stem rot of Pachaco (Schizolobium parahybum Vell Blake) was detected initially in 1988, killing young trees in the Ecuadorian Humed Tropics, since then, thousands of trees are dying annually. The present investigation was made in 2002, where were included three rodales of different ages, located in different provinces. The aim for this research was describe the symptoms its incidence in the zones of study and identifying the associated microorganisms affecting S. parahybum. The disease showed complex symtoms, beginning with a wither of dark, green coloration of the leaves until becoming clorotics. The healed wounds did not show a circular root that affects the crust and xylem, of where emanates fluid of clear yellow color to dark coffee, with strong smell to organic matter in decomposition. In Los Ríos province (rodal more than 25 years old) the greater incidence of the disease was 55 percent, followed by he provinces of Esmeraldas (rodal of 8 years old) and Santo Domingo de Los Tsáchilas (rodal of 4 years old) with 29 and 24 percent respectively. Of ill trees five fungi isolated themselves and identified, three at sort level: Macrophoma sp., Fusarium sp. and Graphium sp. and two at level of species: Ceratocystis paradoxa (Dade) and C. Moniliformis (Hedgc.). The pathogenicity tests demonstrated that C. paradoxa, Macrophoma sp. and C. moniliformis caused the higher values of apparent volume of necrosis with 5.40, 3.55 and 3.48 cm3 respectively.

Comunidades de hongos actinomicetos en tres tipos de vegetación de la Amazonia colombiana: abundancia, morfotipos y el gen 16s ADNr

Communities of Actynomicetes fungy in three vegetation types of the Colombian Amazon: abundance, morphotypes and the 16s rDNA gene. Among soil microorganisms, Actinomycetes play an important role in the sustainability of natural and agricultural systems: decomposition of organic matter; degradation of recalcitrant compounds like lignin; nitrogen fixation; degradation of agricultural chemicals and biological control in plants and animals. We evaluated their diversity in soils under three different vegetation covers (pasture, tropical primary forest and stubble) at two depths in the Southern Colombian Amazon border. We collected five replicates per vegetation type (in each, three samples at 0-20cm and three at 20-30cm; for a total of 30 samples). Abundance and phenotypic diversity were determined by plate counting. Genomic DNA was extracted from the isolates: the 16s rDNA gene was amplified with specific primers, and its genetic diversity was estimated by means of an amplified restriction analysis (ARDRA). Actynomicetes abundance varied with vegetation and depth, possibly reflecting presence of earthworms, macro-fauna and physico-chemical characteristics associated to fertility, as well as organic matter, total bases, and optimal capacity to cationic interchange. Primary forests had the highest diversity. Sixteen morpho-types (six genera) were identified; Streptomyces was the most abundant everywhere. The heterogeneity of ARDRA patterns prevented species identification because of the intra-species variability in sequences of 16s rDNA operons. This community is a biological indicator of landscape alteration and could include new bio-active compounds of pharmaceutical interest. Rev. Biol. Trop. 57 (4): 1119-1139. Epub 2009 December 01.

Los actinomicetos son importantes en la sostenibilidad de sistemas naturales. Su diversidad fue evaluada en suelos de bosque, pastizal y rastrojo, y dos profundidades en el Sur del Trapecio Amazónico Colombiano. Se analizaron suelos de cinco repeticiones por cobertura para un total de 15 unidades. Se tomaron seis muestras en cada unidad y dos profundidades, para un total de 30. Los actinomicetos cultivables se determinaron por recuento en placa, se extrajo ADN, se amplificó el gen ADNr 16s y su diversidad genética se estimó por ARDRA. Hubo diferencias de abundancia entre coberturas y profundidades, relacionadas con la vegetación, presencia de lombrices, macrofauna, altos niveles de materia orgánica, y bases totales. Se obtuvieron valores de diversidad fenotípica similares para las tres coberturas, pero los bosques son más diversos. Se identificaron 16 morfotipos, agrupados en séis géneros, siendo Streptomyces el más abundante. La heterogeneidad de los patrones ARDRA no permitió la asignación de especies, reflejándose variaciones en las secuencias de diferentes operones ADNr 16s en un mismo organismo. Las perturbaciones en la cobertura influyen sobre los actinomicetos, generando cambios en su abundancia y diversidad. Su importancia ecológica permite proponerlos como indicadores biológicos de alteración del paisaje.

First isolation of Cryptococcus gattii molecular type VGII and Cryptococcus neoformans molecular type VNI from environmental sources in the city of Belém, Pará, Brazil

Cryptococcus neoformans and Cryptococcus gattii are important agents of meningoencephalitis in humans in the city of Belém. This clinical data suggests that the region may be a highly endemic area for the pathogenic Cryptococcus species within the state of Pará (PA), Northern Brazil. Preliminary analysis of 11 environmental samples from the city of Belém showed two positive locations, including a hollow of a kassod tree (Senna siamea) colonized simultaneously by C. gattii molecular type VGII and C. neoformans molecular type VNI, and a birdcage in a commercial aviary positive for C. neoformans, molecular type VNI. This is the first evidence of an environmental occurrence of molecular types VNI and VGII in PA.

Primeiro isolamento ambiental de Cryptococcus gattii no Estado do Espírito Santo / First isolation of Cryptococcus gattii from the environment in the State of Espírito Santo

A presença de Cryptococcus gattii foi investigada em diferentes regiões do Estado do Espírito Santo. A maioria (73) das amostras foi coletada de árvores localizadas em lugares públicos de Vitória; 47 amostras foram coletadas de áreas preservadas ou ainda com pouco impacto humano, situados nos arredores desta cidade, a altitudes entre 0 e 900m acima do nível do mar e 48 de árvores nativas das regiões norte e sul do estado. As amostras foram coletadas de ocos e troncos de árvores com auxílio de swab e resultaram em 2 (1,2 por cento) isolados de Cryptococcus neoformans, 2 (1,2 por cento) de Cryptococcus gattii e 1 (0,6 por cento) de Cryptococcus laurentii. A espécie Cryptococcus gattii foi encontrada somente em árvores nativas da região norte, áreas que ainda apresentam resquícios de Floresta Atlântica, enquanto todas as amostras obtidas de vinte e duas espécies de árvores localizadas em área urbana não permitiram a detecção de Cryptococcus gattii. Esses resultados mostram uma possível relação entre ocorrência de Floresta Atlântica e Cryptococcus gattii e confirma que o meio ambiente é fonte de infecção desse fungo.

The presence of Cryptococcus gattii was investigated in different regions of the State of Espírito Santo. The largest number (73) of samples was collected from trees located in public places in Vitória; 47 came from preserved areas or areas with only minor human impact, surrounding this city, at altitudes from 0 to 900m above sea level; 48 came from trees native of the northern and southern regions of the state. The samples were collected from tree hollows and trunks by of swabs and yielded two isolates (1.2 percent) of Cryptococcus neoformans, two (1.2 percent) of Cryptococcus gattii and one (0.6 percent) of Cryptococcus laurentii. The species Cryptococcus gattii was found only in native trees from the northern region, in areas that still have remains of the Atlantic Forest, while none of the samples from any of the 22 tree species located in urban areas was able to show the presence of Cryptococcus gattii. These results show a possible relationship between the presence of Atlantic Forest and occurrences of Cryptococcus gattii. They confirm that the environment is a source of infection with this fungus.

Propagules of arbuscular mycorrhizal fungi in a secondary dry forest of Oaxaca, Mexico

Plant cover loss due to changes in land use promotes a decrease in spore diversity of arbuscular mycorrhizal fungi (AMF), viable mycelium and, therefore, in AMF colonization, this has an influence in community diversity and, as a consequence, in its recovery. To evaluate different AMF propagules, nine plots in a tropical dry forest with secondary vegetation were selected: 0, 1, 7, 10, 14, 18, 22, 25, and 27 years after abandonment in Nizanda, Oaxaca, Mexico. The secondary vegetation with different stages of development is a consequence of slash and burn agriculture, and posterior abandonment. Soil samples (six per plot) were collected and percentage of AMF field colonization, extrarradical mycelium, viable spore density, infectivity and most probable number (MPN) ofAMF propagules were quantified through a bioassay. Means for field colonization ranged between 40% and 70%, mean of total mycelium length was 15.7 +/- 1.88 mg(-1) dry soil, with significant differences between plots; however, more than 40% of extracted mycelium was not viable, between 60 and 456 spores in 100 g of dry soil were recorded, but more than 64% showed some kind of damage. Infectivity values fluctuated between 20% and 50%, while MPN showed a mean value of 85.42 +/- 44.17 propagules (100 g dry soil). We conclude that secondary communities generated by elimination of vegetation with agricultural purposes in a dry forest in Nizanda do not show elimination of propagules, probably as a consequence of the low input agriculture practices in this area, which may encourage natural regeneration.

La vegetación secundaria con diferentes grados de desarrollo es consecuencia de prácticas agrícolas de rozatumba- quema y su posterior abandono. La remoción de la vegetación por cambios de uso de suelo promueve una disminución en la diversidad de esporas, micelio viable y por lo tanto de la colonización de los hongos micorrizógenos arbusculares (HMA), lo cual repercute en la diversidad de la comunidad y como consecuencia en su regeneración. Para evaluar los propágulos de HMA se seleccionaron nueve parcelas con vegetación secundaria con diferentes edades de abandono: 0, 1, 7, 10, 14, 18, 22, 25, 27 años, en la región de Nizanda, Oaxaca, México. Se recolectaron muestras de suelo (seis por parcela) y se cuantificó la colonización de campo, el micelio extrarradical, la densidad de esporas viables, así como la infectividad y el número más probable de propágulos infectivos (NMP). Los promedios de la colonización de campo fueron de 40 a 70 %, el promedio de la longitud de micelio total alcanzó 15.7 ± 1.88 mg-1 suelo seco con diferencias significativas entre parcelas, pero más del 40 % del micelio extraído no fue viable. Se encontraron entre 60 y 456 esporas en 100 g de suelo pero más del 64 % presentaron algún tipo de daño. Los valores de infectividad se encontraron entre 20 % y 50 %, mientras que el NMP presentó un promedio de 85.42 ±44.17 (100 g de suelo seco). Concluimos que las comunidades secundarias generadas por la eliminación de la vegetación con fines agrícolas en la selva baja caducifolia en Nizanda o presentan eliminación de propágulos, probablemente por el bajo impacto de la agricultura, lo cual indica que la regeneración natural es posible.