AGCC. Biotecnología Agroambiente y Salud - MICROBIOTA

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Ontogenia de los estróbilos, desarrollo de los esporangios y esporogénesis de equisetum giganteum (Equisetaceae) en los Andes de Colombia
(2011-12) Rincón Barón, Edgar Javier; Forero Ballesteros, Helkin Giovani; Gélvez Landazábal, Leidy Viviana; Torres, Gerardo Andrés; Rolleri, Cristina Hilda
Ontogeny of strobili, sporangia development and sporogenesis in Equisetum giganteum (Equisetaceae) from the Colombian Andes. Studies on the ontogeny of the strobilus, sporangium and reproductive biology of this group of ferns are scarce. Here we describe the ontogeny of the strobilus and sporangia, and the process of sporogenesis using specimens of E. giganteum from Colombia collected along the Rio Frio, Distrito de Sevilla, Piedecuesta, Santander, at 2 200m altitude. The strobili in different stages of development were fixed, dehydrated, embedded in paraffin, sectioned using a rotatory microtome and stained with the safranin O and fast green technique. Observations were made using differential interference contrast microscopy (DIC) or Nomarski microscopy, an optical microscopy illumination technique that enhances the contrast in unstained, transparent. Strobili arise and begin to develop in the apical meristems of the main axis and lateral branches, with no significant differences in the ontogeny of strobili of one or other axis. Successive processes of cell division and differentiation lead to the growth of the strobilus and the formation of sporangiophores. These are formed by the scutellum, the manubrium or pedicel-like, basal part of the sporangiophore, and initial cells of sporangium, which differentiate to form the sporangium wall, the sporocytes and the tapetum. There is not formation of a characteristic arquesporium, as sporocytes quickly undergo meiosis originating tetrads of spores. The tapetum retains its histological integrity, but subsequently the cell walls break down and form a plasmodium that invades the sporangial cavity, partially surrounding the tetrads, and then the spores. Towards the end of the sporogenesis the tapetum disintegrates leaving spores with elaters free within the sporangial cavity. Two layers finally form the sporangium wall: the sporangium wall itself, with thickened, lignified cell walls and an underlying pyknotic layer. The mature spores are chlorofilous, morphologically similar and have exospore, a thin perispore and two elaters. This study of the ontogeny of the spore-producing structures and spores is the first contribution of this type for a tropical species of the genus. Fluorescence microscopy indicates that elaters and the wall of the sporangium are autofluorescent, while other structures induced fluorescence emitted by the fluorescent dye safranin O. The results were also discussed in relation to what is known so far for other species of Equisetum, suggesting that ontogenetic processes and structure of characters sporoderm are relatively constant in Equisetum, which implies important diagnostic value in the taxonomy of the group.
Acceso abierto
Simbiosis micorrízica arbuscular y acumulación de aluminio en brachiaria decumbens y manihot esculenta
(2012-07) Guerra Sierra, Beatriz Elena; Chacón, Martha Rocio
Oil palm (Elaeis guineensis Jacq) soils from-Santander Puerto Wilches-Colombia, have low fertility, high aluminum saturation and low density of mycorrhizal fungal spores. Behavior mycorrhizal symbiosis was evaluated XVLQJ QDWLYH VRLOV ZLWK P\FRUUKL]DH 0$ DQG VWHULOH VRLOV ZLWKRXW mycorrhizae (MA -) using Brachiaria decumbens and Manihot esculenta, both plants have high mycotrophy and ion binding capacity of aluminum. Variables were spore density, percentage of mycorrhizal colonization, biomass and root length, concentration of aluminum at leaf and root. Was performed (ANOVA) with a two-way general linear model. There were mycorrhizal colonization rates exceeding 70% in B. decumbens in soils with concentrations of 0,6 and 1,4 meq/100 g of aluminum. M. esculenta establishedmycorrhizationat 50% in all four soils. Spores were increased up to 200% in the two hosts plants. Aluminum concentrations were higher in mycorrhizal roots, while leaf-level values were lower.
Acceso abierto
Indigenous arbuscular mycorrhizal fungi in oil palm soils in Colombia
(2013-09) Guerra Sierra, Beatriz Elena; Serge, Sokolski; Dion, Patrice
Generally monocultures have replaced tropical forests and other ecosystems, causing big changes and little is known about the influence of the practice of monoculture in density and biodiversity of mycorrhizal fungi (AMF) species. Spore production is highly depend of physiologycal parameters of the AMF and on environmental conditions, however it is known that in nutrient-poor soils of the humid tropics many plants are obligate mycotrophs or ecologically dependent on AMF. In Oil palm (Elaeis guineensis Jacq), the limited development of their root system and field observations of high levels of mycorrhizal colonization, suggest that this crop benefits greatly from the symbiosis.[1]Isolation of soil spores and subsequent microscopic examination is a routine procedure in the recognition of AMF species, however the study of walls by light microscopy is a difficult task; interpretation depends on several factors such as the type of microscope and lighting mounting means and observer experience.Based on the morphological characteristics of the AMF described approximately 200 species (2).As a complement to morphological studies AMF wall light microscopy has been used transmission electron microscopy (TEM) and scanning electron microscopy (SEM), however the publications in this field are limited. Another limitation of morphologycal identification is the fact that field- collected spores are often parasitized or degraded and therefore unidentifiable. A methodology for increased healthy spores are AMF trap cultures ,soil samples from the field site are brought into contact with suitable plant hosts of AMF under controlled conditions in order to propagate the species, additionally the plant species used in the trap cultures may have an influence on which AMF are detected , aditionaly the molecular identification is a good tool for the identification of AMF, almost all identification systems for AMF are based on the ribosomal DNA (rDNA) , this is highly polymorphic in single spores of AMF. The aim of this study was to determine the initial density of native mycorrhizal fungi spores in soils of oil palm monocultures, and the identification of AMF species increased in trap cultures under controlled greenhouse conditions . Mycorrhizal fungi spores were identified using optical and scanning microscopy, and molecular analysis was useful for identifying some species of Glomus.
Acceso abierto
Evaluación de la patogenicidad de Xenorhabdus spp. nativos en Colombia
(2014-07) Guerra-Sierra, Beatriz Elena; Chacón, Julie Giovanna; Muñoz Flórez, Jaime Eduardo; Caicedo, Ana Milena
Xenorhabdus and Photorhabdus bacteria are symbiotically associated with nematodes of the Steinernematidae and Heterorhabditidae families respectively. They are characterized by producing a complex of substances such as toxins, antibiotics and extracellular enzymes that kill insects. In order to select the most pathogenic nematodes and antibiotic production level, it was propose to evaluate the pathogenicity of 13 native isolates. Bacteria were isolated from infective juveniles (JIS) by direct macerated, cultured on selective media (NBTA and MacConkey) and described phenotypic and biochemically. The pathogenicity was evaluated on the last instar larvae of G. mellonella, using serial dilutions of the bacterial inoculum with a concentration of 104cel/ml. The mortality rate was registered at 12, 24 and 48 hours and the colony forming units (CFU) in NBTA agar in the same intervals of time. The data were analyzed by variance analysis and mean comparison by Duncan test. Biochemical and enzymatic tests were positive for the genus Xenorhabdus. The results showed that the isolates UNPX04, UNPX15 from agricultural soils of Florida -Risaralda and Llano Bajo- Valle del Cauca respectively, caused 100% of mortality at 12 and 24 hours in contrast with seven isolations that caused only 70% of mortality.
Acceso abierto
A new Multiplex-PCR for urinary tract pathogens detection using primer design based on an evolutionary computation method
(2015-06) García Sánchez, Liliana Torcoroma; Cristancho, Laura Maritza; Vera, Erika Patricia; Begambre, Oscar
This work describes a new strategy for optimal design of Multiplex-PCR primer sequences. The process is based on the Particle Swarm Optimization-Simplex algorithm (Mult-PSOS). Diverging from previous solutions centered on heuristic tools, the Mult-PSOS is selfconfigured because it does not require the definition of the algorithm’s initial search parameters. The successful performance of this method was validated in vitro using Multiplex-PCR assays. For this validation, seven gene sequences of the most prevalent bacteria implicated in urinary tract infections were taken as DNA targets. The in vitro tests confirmed the good performance of the Mult-PSOS, with respect to infectious disease diagnosis, in the rapid and efficient selection of the optimal oligonucleotide sequences for Multiplex-PCRs. The predicted sequences allowed the adequate amplification of all amplicons in a single step (with the correct amount of DNA template and primers), reducing significantly the need for trial and error experiments. In addition, owing to its independence from the initial selection of the heuristic constants, the Mult-PSOS can be employed by non-expert users in computational techniques or in primer design problems.
Acceso abierto
Differential anti-proliferative effect on K562 leukemia cells of Lippia alba (Verbenaceae) essential oils produced under diverse growing, collection and extraction conditions
(2017-02) García Sánchez, Liliana Torcoroma; Leal, Andrés Felipe; Moreno Moreno, Erika Marcela; Stashenko, Elena E.; Arteaga, H. José
Lippia alba (Verbenaceae Family) is an aromatic shrub native to Latin America, with recognized medicinal properties and a well-known high phenotypical plasticity in response to environmental factors. In order to identify the parameters that potentiate its in vitro anti-proliferative effect on human leukemia cells (K562), a matrix was designed for the production of 76 essential oils (EOs) with variations in plant growing season, harvested part from the plant, and preservation and distillation material conditions. The results show that EOs obtained from the same L. alba chemotype (Citral or Carvone), but acquired under different environmental or extraction conditions, presented significant differences in their primary components, oil yield, and cytotoxic activity on K562 cells. Citral EOs produced under diverse conditions displayed a cytotoxic effect on tumour cells ranging from 54 to 95% (IS 1.8–8.6) and IC50 from 13 to 38.8 μg/mL. The differences in antiproliferative activity were significantly correlated with variations in the β-caryophyllene oxide concentration. These results show the value of using standardized production conditions for the commercial utilization of L. alba EOs.
Acceso abierto
Nueva reacción en cadena de la polimerasa múltiple para el diagnóstico específico de especies implicadas en la candidiasis humana
(2017-06) García Sánchez, Liliana Torcoroma; Luna, Liany Johanna; Velasco, Tania Katherine; Guerra Sierra, Beatriz Elena
Introduction: Candidiases is a group of opportunistic infections caused by yeasts belonging to the genus Candida. Candida albicans is the most prevalent species in both superficial and deep infections, however, the clinical importance of non-albicans Candida has increased during the last decade, driving an urgent need for diagnostic tests that allow for species-level resolution and selection of the optimum therapeutic approach.Objective: To design and to optimize a new multiplex PCR assay for the simultaneous identification of the five most relevant species of Candida involved in human candidiasis etiology.Materials and methods: For primers design, the physical and thermodynamic restrictions that affect multiplex PCR performance were analyzed using Gene Runner and Mult-PSOS. As templates, the internal transcribed region 2 (ITR2) was selected for C. albicans (AJ249486.1), and topoisomerase II (TOPII) for C. parasilopsis (AB049144.1), C. krusei (AB049139.1), C. tropicalis (AB049141.1), andC. guillermondii (AB049145.1). We used ATCC strains of all these five species and clinical isolates as templates.Results: We designed ten oligonucleotides for the simultaneous amplification of the Candida species. The electrophoresis band profile was: C. albicans (206 bp), C. guillermondii (244 bp), C. tropicalis (474 bp), C. parasilopsis (558 bp), and C. krusei (419 bp). Conclusion: The new multiplex PCR assay designed in this study allowed a simultaneous and efficient amplification of the amplicons corresponding to the five species of Candida under study, with an adequate resolution in standard agarose gel.
Acceso abierto
Producción de xilitol a partir de hidrolizados ácidos no detoxificados de bagazo de sorgo por debaryomyces hansenii
(2018-10) Ledezma Orozco, Edgar; Ruíz Salazar, Régulo; Bustos Vázquez, Guadalupe; Montes García, Noé; Roa Cordero, Martha Viviana; Rodríguez Castillejos, Guadalupe
The industrial production of xylitol is carried out with the chemical hydrogenation of D-xylose and it is a costly process. An alternative procedure is the fermentation of lignocellulosic residues with yeasts such as Debaryomyces hansenii (Zopf) Lodder and Kreger-van Rij. Therefore, the objective of this study was to evaluate the extraction of xylitol from sorghum straw, in detoxified and non-detoxified media. White sorghum straw [Sorghum bicolor (L.) Moench.], variety RB-Paloma, was hydrolyzed with H2 SO4 at 2, 4 and 6 %; solid liquid ratio 1:6, 1:8 and 1:10; all treatments at 120 °C for 80 min. Those hydrolyzed were neutralized and used to evaluate the production of xylitol; culture media contained 30, 40 or 50 g L-1 xylose were inoculated with D. hansenii and incubated at 30 and 35 °C, 150 and 200 RPM for 96 h. In addition, the data were analyzed with ANDEVA and means tests (p £ 0.05). The maximum concentration of xylitol in the detoxified media was 28.8 g L-1 (40 g xylose, 35 °C, 200 rpm), and in non-detoxified, the maximum found was 29.23 g L-1 (30 g xylose, 35 °C, 150 rpm). The straw evaluated could be used to obtain xylose with a potential use in media for fermentation, and results also suggest that D. hansenii can metabolize xylose in the presence of acetic acid and furfural.
Acceso abierto
Contribución a la conservación de Orchidiaceas de Santander mediante cultivo in vitro de semillas
(Bucaramanga : Universidad de Santander, 2018, 2018-12-01) Chacón Velasco, Martha Rocío; Contreras Acero, Olga Marina; Cáceres Cárdenas, Helmar Ernesto; Universidad de Santander
El registro de la diversidad de orquídeas en Colombia es sorprendente; los inventarios realizados emiten cálculos aproximados, pero se modifican en la medida que se exploran diversas áreas. Estudios realizados en Santander en el 2011 precisaron la existencia de cerca de 3.500 a 4.000 especies en más de 230 géneros, cifra que corresponde al 10 % de las especies existentes y al 25 % del total de los géneros a nivel mundial. Para 2012 fueron reportadas 4.010 especies distribuidas en 260 géneros y en el 2013 se presentó un registro de cerca de 4.100 especies agrupadas en 232 géneros. Para el 2015 el Ministerio de Ambiente y Desarrollo Sostenible a través del Sistema de Información sobre Biodiversidad de Colombia (SIB) afirmó que Colombia cuenta con el mayor número de especies de orquídeas en el mundo, con un total de 4.270 registradas, agrupadas en 274 géneros distribuidos en casi todo el territorio nacional; un total de 1.572 especies son exclusivas del país. El departamento de Santander ocupa actualmente el segundo lugar en riqueza, con un 14 %, de orquídeas a nivel nacional después del departamento de Antioquia. Santander presenta especies endémicas con distribución restringida. Sea el caso mencionar a Catasetum lucis, Sobralia uribei y Santanderella amadorinconiana, las cuales no cuentan con protección para su conservación. Los investigadores del Instituto Humboldt elaboraron una lista de especies amenazadas en Colombia y mencionaron que las familias con mayor número de especies en peligro son las orquídeas, seguidas de las palmas y las pasifloráceas (Ochoa, 1998). Dentro de las principales causas de extinción está la destrucción de sus hábitats y expansión de la frontera agrícola como las de mayor impacto, que hace prioritario plantear estrategias para frenar la pérdida de especies; entre ellas: la conservación in situ de áreas donde se encuentran los árboles hospederos, insectos y hongos micorrízicos, entre otros. Pero además la ejecución de proyectos de investigación que propendan por la creación tanto de bancos de germoplasma (preservación de semillas, células, tejidos, órganos o plantas bajo cultivo in vitro o nitrógeno líquido), así como el cultivo de plantas en vivero. De igual manera los estudios en los aspectos taxonómicos, poblacionales, interacciones ambientales, polinización, biología reproductiva, propagación in vitro y ex situ serán de gran impacto para la protección de este recurso floral nativo. El ciclo de vida sexual de las orquídeas comprende la germinación de semillas, desarrollo de protocormos, diferenciación de plantas, etapa reproductiva o floración, polinización, fecundación y dispersión de semillas. El porcentaje de germinación de las semillas de Orchidaceas en condiciones naturales es muy bajo en comparación con el número de semillas producido en cada cápsula; esto obedece a que la cubierta alberga un embrión que no almacena sustancias nutritivas. Por ello estas deben encontrar soportes adecuados como cortezas de árboles que les suministre nutrientes y establecer asociación micorrízica con hongos basidiomicetes del grupo Rizocthonia sensu latu, un grupo artificial que incluye hongos cuyas etapas sexuales pertenecen a los géneros Thanatephorus, Ceratobasidium, Sebacina y Tulasnella para garantizar de manera exitosa el proceso germinativo. La técnica de cultivo in vitro está siendo usada en varios países como uno de los medios que permiten conservar poblaciones silvestres , así como el desarrollo de paquetes tecnológicos adoptados por horticultores, comunidades organizadas e interesadas en la explotación racional de sus recursos para disminuir en gran medida la presión de la colecta de poblaciones silvestres (Salazar y Mata, 2003). Además dicha técnica favorece la variabilidad genética de las poblaciones (Arditti, 1993). El cultivo de semillas de orquídeas como modalidad del cultivo in vitro de las plantas superiores, tiene como finalidad el acortamiento del ciclo de mejora, sustitución de la simbiosis (micorrizas) y evitar la competición con otros microorganismos. Se espera que el presente documento pueda brindar a estudiantes de diferentes disciplinas, cultivadores y toda persona amante de las orquídeas las bases para comprender el ciclo de vida de las orquídeas, el estado de vulnerabilidad que presentan algunas especies de la región y el papel protagónico que ha tenido hasta el momento la técnica del cultivo in vitro de semillas como herramienta de propagación alterna para incrementar el volumen poblacional a nivel mundial y nacional de las orquídeas endémicas.
Acceso abierto
Antifungal activity of acidic electrolyzed water against strawberry postharvest molds (Fragaria x ananassa Duch cv. Camarosa)
(2019-04-01) Guerra-Sierra, Beatriz Elena; Sandoval-Meza, Adriana Ximena; García-Sanchéz, Liliana Torcoroma; Microbiota
The aim of this word was to assess the in vitro antifungal activity of acidic electrolyzed water (AEW) and the required contact time to inhibit the development of post-harvest molds common in strawberry fruit. Ninetyfour strawberry samples were used. A five-fold assay in a randomized design was carried out using standard inoculum of fungal conidia, which were subjected to an array of contact times and AEW concentrations, using a controlled agitation (120 r.p.m) at 23°C. The conidia treated with AEW were grown on potato dextrose agar and their germination was evaluated. Mycelial growth of the treated samples was measured and compared against conidia control samples treated with distilled water instead of AEW. Botrytis cinerea and Rhizopus stolonifer were the most commonly isolated species at 54.25% and 28.72%, respectively. AEW inhibited conidia germination after 7 minutes of exposure. The AEW concentration required to inhibit conidia germination was 10 ppm and 50 ppm for R. stolonifer and B. cinerea respectively, a variance possibly due to the constitution of their cellular walls. A short exposure of AEW is able to inhibit post-harvest fungi growth, and is thus recommended as an efficient, economical, and environmentally sustainable sanitation agent, with the ability of extending the strawberry postharvest consumption period.
Acceso abierto
ZnO-based nanofungicides : Synthesis, characterization and their effect on the coffee fungi Mycena citricolor and Colletotrichum sp.
(2019-05) Arciniegas Grijalba, P.A.; Patiño Portela, M.C.; Mosquera Sánchez, L.P.; Guerra Sierra, Beatriz Elena; Muñoz Flórez, Jaime Eduardo; Erazo Castillo, L.A.; Rodríguez Páez, J.E.
mical route and a ZnO-based nanobiohybrid obtained by green synthesis in an extract of garlic (Allium sativum). To find out the characteristics of the materials synthesized, X-ray diffraction (XRD), IR spectroscopy and absorption in UV–Vis were used, as well as both scanning (SEM) and transmission (TEM) electron microscopy. The results showed that the samples obtained were of nanometric size (< 100 nm), with a predominance of the wurtzite crystal phase of ZnO and little crystallization of the nanobiohybrids. Their antifungal capacity on two pathogenic fungi of coffee, Mycena citricolor (Berk and Curt) and Colletotrichum sp. was also evaluated. Both nanomaterials showed an efficient antifungal capacity, particularly the nanobiohybrids, with ~97% inhibition in growth of M. citricolor, and ~93% for Colletotrichum sp. The microstructural study with high resolution optical (HROM) and ultra-structural microscopy (using TEM) carried out on the fungi treated with the synthesized nanomaterials showed a strong nanofungicidal effect on the vegetative and reproductive structures and fungal cell wall, respectively. The inhibition of the growth of the fungi and micro and ultra-structural affectations were explained considering that the size of the nanomaterials allows them to pass easily through the cell membranes. This indicates that they can be absorbed easily by the fungi tested here, causing cellular dysfunction. Nanofungicide effects are also attributable to the unique properties of nanomaterials, such as the high surface-tobulk ratio of atoms and their surface physicochemical characteristics that could directly or indirectly produce reactive oxygen species (ROS), which affect the proteins of the cell wall.
Acceso abierto
Inhibition of C. albicans dimorphic switch by cobalt(II) complexes with ligands derived from pyrazoles and dinitrobenzoate: Synthesis, characterization and biological activity
(2019-07-01) Fonseca, Daniela; Leal-Pinto, Sandra Milena; Roa-Cordero, Martha Viviana; Vargas, Jose D.; Moreno-Moreno, Erika Marcela; Macias, Mario A.; Suescun, Leopoldo; Muñoz-Castro, Alvaro; Hurtado, John J.; Microbiota
Seven cobalt(II) complexes of pyrazole derivatives and dinitrobenzoate ligands were synthesized and characterized. The single-crystal X-ray diffraction structure was determined for one of the ligands and one of the complexes. The analysis and spectral data showed that all the cobalt complexes had octahedral geometries, which was supported by DFT calculations. The complexes and their free ligands were evaluated against fungal strains of Candida albicans and emerging non-albicans species and epimastigotes of Trypanosoma cruzi. We obtained antifungal activity with a minimum inhibitory concentration (MIC) ranging from 31.3 to 250 µg mL−1. The complexes were more active against C. krusei, showing MIC values between 31.25 and 62.5 µg mL−1 . In addition, some ligands (L1–L6) and complexes (5 and Co(OAc)2 · 4H2O) significantly reduced the yeast to hypha transition of C. albicans at 500 µg mL−1 (inhibition ranging from 30 to 54%). Finally, the complexes and ligands did not present trypanocidal activity and were not toxic to Vero cells. Our results suggest that complexes of cobalt(II) with ligands derived from pyrazoles and dinitrobenzoate may be an attractive alternative for the treatment of diseases caused by fungi, especially because they target one of the most important virulence factors of C. albicans.
Acceso abierto
Ontogenia e histoquímica de los esporangios y escamas receptaculares del helecho epífito Pleopeltis macrocarpa (Polypodiaceae)
(2019-12-05) Rincon-Baron, Edgar Javier; Guerra-Sierra, Beatriz Elena; Restrepo Zuluaga, David Esteban; Espinosa-Matías, Silvia; Microbiota
Ontogeny and histochemistry of sporangia and receptacle scales of the epiphytic fern Pleopeltis macrocarpa (Polypodiaceae).Introduction: The ontogeny of sporangia and furthermore the struc-ture and function of the receptacle scales showed by the sori of some fern species are topics scarcely represented in the scientific literature. Objectives: To describe and analyze the ontogeny of sporangia and receptacle scales of Pleopeltis macrocarpa. Methods: During March and April of 2017, fertile fronds of P. macrocarpa were col-lected from tree stems located in the plant nursery “El Edén de las flores”, municipality of Rionegro, Antioquia, Colombia. The samples were fixed and processed according to the standard protocols for embedding and sec-tioning in paraffin and resin. Sections obtained in resin (0.5 μm) were stained with Toluidine blue. The additional descriptions of the anatomy and histochemistry required specific reagents, applied for the determination of pri-mary walls, secondary walls, nuclei, lignin, polyphenols, polysaccharides, pectic substances and cellulose. The observations and photographic records were performed by photonic and epifluorescence microscopy. For the scanning electron microscopy (SEM) technique, the sori were dehydrated with 2,2- Dimethoxypropane, dried to critical point and coated with gold. Results: The sori are superficial, vascularized and have mixed development, covered by receptacle scales that detach as the sporangia reaches maturity. The leptosporangiate type sporan-gium have long stalks of primary walls, the annulus of the sporangia shows secondary walls with “U” shaped thickenings rich in lignin. The epidermal cells of the receptacle originate the sporangia and receptacle scales. The mitotic division events of these two structures are initially similar, but then diverge for the reproductive and vegetative differentiation of these two organs. Meiosis is simultaneous and the spore tetrads are arranged in a decussate or tetragonal shape. The cellular tapetum is initially unstratified but becomes bistratified by mitotic division. The inner layer of the tapetum cells break originating a plasmodial tapetum. During the sporoderm development, the first structure formed is the exospore, composed of sporopolenin, followed by the endospore composed of cellulose, pectin and carboxilated polysaccharides, and finally the perispore. The histochemistry and epifluorescence results indicate that both the sporangia and immature receptacle scales have cell walls of cellulosic. These structures as well as those of the sporangium wall cells maintain its composition during matu-ration. Whereas, the epidermal wall cells of the shields from the mature receptacle scales are characterized by thickened cuticle. The polyphenols are present during all the development stages of the sporangia and receptacle scales. Starch is abundant in the early stages of development of the receptacle cells and sporangial primordia. Conclusions: The ontogeny of the sporangia of P. macrocarpa is similar to the described for leptosporangiate ferns. The receptacle scales are mainly protective structures, its morphology and cell wall composition prevent desiccation or humidity loss of the sporangia during the labile stages of development. These results agree with the protective function attributed to the peltated pluricellular scales present in the vegetative structures of drought tolerant species of ferns and angiosperms.
Acceso abierto
Alteraciones histopatológicas causadas por la roya puccinia nakanishikii (Pucciniales: pucciniaceae) en plantas de cymbopogon citratus (poaceae)
(2020-02-13) Rincón-Barón, Edgar Javier; Gutierrez-Rodriguez, Ana Mariany; Guerra-Sierra, Beatriz Elena; Espinosa Matías, Silvia; Microbiota
Histopathological alterations caused by Puccinia nakanishikii rust (Pucciniales: Pucciniaceae) in Cymbopogon citratus (Poaceae) plants. Introduction: Histopathological and histochemical aspects linked to the attack of fungal rusts to plants, as well as its relation with the different spore stages are topics rather scarce in the scientific literature. Objective: To describe and analyze the histopathological and histochemical aspects of Cymbopogon citratus and its relation with the different stages of the spores from the rust fungi Puccinia nakanishikii. Methods: During the months April and August 2013, leaves healthy and infected by Puccinia nakanishikii were collected in the Northwestern scarp of the Bucaramanga-Colombia plateau. The samples with injuries on diverse developmental stages were fixated and processed according to the standard protocols for embedding and sectioning in paraffin and resin. Sections obtained from paraffin (5-7 μm) were stained with Safranin-Alcian blue and Alcian blue-Hematoxylin. On the other hand, sections obtained from resin (0.5 μm) were stained with Toluidine blue. Further, freehand sections were obtained for an autofluorescence analysis. The observations and photographic record were done via photonic microscope and epifluorescence microscope. For the observations via scanning electron microscopy (SEM), the samples were fixated in Glutaraldehyde, dehydrated with 2,2 dimethoxypropane, then desiccated to critical point and finally coated with gold. Results:The leaves are generally hypostomatic, with long and short epidermic cell forming parallel rows and showing unicellular prickle trichomes and micro-trichomes. The abaxial surface is covered by epicuticular wax forming a dense layer. The adaxial epidermis is formed by groupings of bulliform cells and epidermal cells with rectangu-lar or squared contour. In the mesophyll, there is no differentiation between palisade and spongy parenchyma, its anatomy reflects the C4 metabolism. The formation of uredosori and teliosori both hypophyllous was observed. Urediniospores are the reinfecting agents phase, they have 4-5 equatorial germ pores and echinulate wall. Teliospores have smooth wall and a persistent pedicel. The urediniospores form a germ tube, generally on the abaxial leaf surface, these tubes develop towards the stomata reaching the mesophyll interior. No appressorium were observed. The epidermis limiting the uredosorus detaches due the development and pressure that exert both the urediniospores and capitate paraphyses. As the infection progresses, autofluorescense of the chloro-phyll is lost and the cells undergo necrotic processes. Afterwards, the phloem collapses and the xylem becomes slightly disorganized. At this moment, the infection is extended along the whole leaf blade, resulting in the leaf death and the plant defoliation. On advanced stages of the infection, the uredosori showed pycnidia, probably belonging to the hyperparasite Sphaerellopsis, these structures were closely associated to the rust infected tissues. Conclusions:Puccinia nakanishikii develops on the leaves of Cymbopogon citratus producing uredosori and teliosori. Urediniospores are the reinfective stage, teliospores were only observed at late stages of the infection. The epidermis and photosynthetic tissue are severely affected by cell necrosis. The vascular tissues are deeply affected on the advances stages of the infection.
Acceso abierto
Antifungal effect of zinc oxide nanoparticles (ZnO-NPs) on Colletotrichum sp., causal agent of anthracnose in coffee crops
(2020-05-05) Mosquera-Sanchez, L.P.; Arciniegas-Grijalba, P.A.; Patiño-Portela, M.C.; Guerra–Sierra, Beatriz Elena; Muñoz-Florez, J.E.; Rodríguez-Páez, J.E.; Microbiota
Coffee cultivation around the world is affected by phytopathogenic fungi, among them Colletotrichum sp., the causative agent of anthracnose. In the present work, therefore, an in vitro study was carried out on the antifungal effect of zinc oxide nanoparticles (ZnO-NPs) obtained by a chemical route on Colletotrichum sp. To this end, the area of growth of the fungus exposed to the action of concentrations of 9 mmolL−1 (730 ppm), 12 mmolL−1 (980 ppm), and 15 mmolL−1 (1200 ppm) of ZnO-NPs was monitored and their behavior was compared with the effect of the fungicide, ciproconazole (positive control) as well as with a sample of the fungus that grew normally (negative control). The ZnO-NPs showed an appreciable percent inhibition of fungal growth, ~96% for the concentration of 15 mmolL−1 at 6 days, causing loss in the continuity of some hyphae and the formation of groups of hyphal structures. Additionally, the ZnO-NPs favored the formation of structures of compact appearance (similar to vacuoles) within the hypha, as well as decreasing the cytoplasmic space.
Acceso abierto
Foliar anatomy of ten genotypes of the plant manihot esculenta (Euphorbiaceae)
(2020-07-03) Marín, Jaime; Rincón-Barón, Edgar Javier; Montoya-Lerma, James; Microbiota
Cassava Manihot esculenta (Crantz) is a perennial shrub native to South America that is an essential source of carbohydrates for more than 600 million people in tropical countries. Objective: The aim of this study was to describe and compare the leaf blade anatomy of ten genotypes of cassava. Methods: The methodology for anatomical descriptions was processed and 30 leaves of each of the varieties were included and sectioned according to paraffin impregnation protocols. Results: The results showed that the leaf blade anatomi-cal structure of all the varieties in general terms show differences. All varieties had monostratified epidermis, leaf mesophyll consisted of a palisade parenchyma in a single layer and multiple layers of spongy parenchyma. Polyphenolic idioblasts were observed immersed in the palisade parenchyma and spongy parenchyma. Between 3-7 xylem ribs with their respective phloem were found in the midrib in almost all varieties. Trichomes were only found in two varieties (NAT31-ECU72) and leaves were all hipostomatic. Conclusions: The results reveal that NAT31 is the material with the most anatomically marked differences (i.e. presence of trichomes, papil-lary cell, and, on the adaxial face, special provision in the arrangement of stomata and epicuticle wax patterns), characteristics that might be related to pest resistance.
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Alteraciones anatómicas e histoquímicas ocasionadas por la oidiosis en hojas de Hydrangea macrophylla (Hydrangeaceae)
(2020-07-03) Rincón-Barón, Edgar Javier; Grisales-Echeverri, Claudia; Cuaran, Viviana Lucia; Cardona-B., Nadya Lorena; Microbiota
Anatomical and histochemical alterations caused by powdery mildew on Hydrangea mac-rophylla (Hydrangeaceae) leaves. Introduction: There are few studies concerning the morpho-anatomical and histochemical alterations caused by powdery mildew in H. macrophylla leaves in the scientific literature. Objective: To describe and analyze anatomical and histochemical aspects of this pathosystem. Methods: More than 90 leaves of H. macrophylla (both healthy and infected leaves by powdery mildew) were collected in the nursery El Jardín del Eden, Rionegro, Antioquia, Colombia. To carry out the identification of the mycopatho-gen, sections were stained with Lactophenol Blue, and contrasted with specialized taxonomic keys. Transverse fragments 1 cm thick were fixed in a mixture of formalin, alcohol, and acetic acid. These were subsequently dehydrated using an ethanol series, clarified in Xylene, and finally embedded in Paraplast plus® to obtain 5 μm sections. Schiff’s periodic acid reaction (PAS) was used to detect structural and reserve polysaccharides, Ruthenium Red for pectins, Ponseau S and Lacmoid for callose, ferric chloride for polyphenols, Sudan Black for lipids and Uvitex 2B-Hematoxylin for chitin. The sections were observed using a Nikon 80i eclipse® pho-ton microscope, with Uvitex 2B-Hematoxylin-stained sections examined by epifluorescence using a UV-2A filter. For the observation and description of the samples by scanning electron microscopy, healthy and infected leaves were fixed and dehydrated in 100 % methanol, critical point dried, and coated with gold. Results:H. macrophylla leaves are isobilateral and homobaric, with adaxial and abaxial epidermis of a single cellular layer. The palisade parenchyma consists of a layer of short cells, while the spongy parenchyma forms 6 to 7 cellular layers. All vascular bundles in the leaf blade are closed collaterals. Abundant idioblasts with raphides may be observed in the mesophyll, and starch is the main reserve carbohydrate present in the tissues. The leaves are hypostomatic and exhibit a paracytic pattern of superficial stomata which possess large substomatal cavities. The morphological data observed indicate that the mycopathogen is related to the genus Erysiphe. The epidermal cells affected by the pathogen exhibit thickened walls, granular cytoplasm, and papillae or cell wall appositions in the outer periclinal walls. With the deterioration of the epidermis, the underlying tissues are affected and become necrotic. Histochemical test indicate that infected plants thicken and reinforce their epidermal cell walls with primary wall materials; primarily cutin, pectins, and callose. When stained with Sudan Black, the presence of dark-colored agglomerates in the cytoplasm of epidermal cells may be related to plant defense mechanisms; and those observed in mesophilic cells to the disorganization of membrane systems. Polyphenols accumulate in the cytoplasm of infected epidermal cells. The fungal material present in epidermal tissues was clearly differenti-ated when stained with fluorochrome to detect chitin. Conclusions: Species of the genus Erysiphe are causative agents of powdery mildew in H. macrophylla. Necrosis of the epidermal cells is observed in response to the mycopathogen, possibly due to hypersensitive response.
Acceso abierto
Evolution of the porous structure of cocoa beans during microwave drying
(2020-07-05) Alean, Jader; Chejne, Farid; Maya, Juan C.; Camargo-Trillos, Diego; Ramírez, Say; Rincon-Baron, Edgar Javier; Rojano, Benjamin; Microbiota
In this work, it was evaluated the morphological changes of the porous structure of the cocoa bean samples subjected to microwave drying. The use of microwaves (MWs) applied by ON-OFF on cocoa bean samples allowed to avoid both the burning and the roasting of the beans. During the MWs drying process, phenomena of breakage of cellular structure, coalescence and, pore plugging altered the average pore diameter, the pore volume, surface area, and Pore Size Distribution (PSD). When the results of sun-dried beans were compared with those of beans dried by MWs, it was concluded that the average pore diameter, the pore volume, the surface area and, PSD were also affected by the solar drying; however, the breakage of cellular structure did not occur.
Acceso abierto
Impacts of Arbuscular Mycorrhizal Fungi on Rice Growth, Development, and Stress Management With a Particular Emphasis on Strigolactone Effects on Root Development
(2021-03-15) Debasis, Mitra; Guerra Sierra, Beatriz Elena; Bahman, Khoshru; De Los Santos Villalobos, Sergio; Belz, Claudia; Chaudhary, Priya; Shahrig, Faride Noroozi; Rihab, Djebaili; Nurudeen, Olatunbosun Adeyemij; El-Ballatk, Enas M.; El-Esawik, Mohamed A.; Moradic, Shokufeh; Mondall, Rittick; Senapati, Ansuman; Panneerselvam, Periyasamy; Das Mohapatra, Pradeep K.; Microbiota
Arbuscular mycorrhizal fungi (AMF) are widely distributed soil-borne microorganisms, which have a symbiotic relationship with several terrestrial plants. They play a key role in plant growth promotion and development, plant nutrient homeostasis, soil nutrient management, and induction of plant defense mechanisms against pest infestation and disease incidences. This interaction of AMF with rice plants has been studied in great detail, providing distinct perspectives on the natural basis of nutrient transport, stress management, improvement of soil health, and induction of systemic plant resistance. This review highlights the responses of (i) AMF interaction with rice plants, (ii) AMF colonization and sporulation potential in rice rhizosphere, (iii) AMF species as a source of inoculum for rice production, (iv) AMF for rice plant maintenance and durability, and (v) AMF responses to other soil microorganisms. Additionally, a new class of phytohormones known as strigolactone (SLs) has been briefly described covering the various forms of analogs, isomers, and membrane transporters. The role of SLs in pre-symbiotic molecular talks, induction of energy metabolism in mitochondria, spore germination, stimulation of hyphal branches, and the relationships of SLs synthesis with soil nutrient content provides in-depth insights into the mechanisms involved in improving AMF interactions with rice plants.
Acceso abierto
Phytoremediation of heavy metals in tropical soils an overview
(2021-03-27) Guerra Sierra, Beatriz Elena; Muñoz Guerrero, Jaider; Sokolski, Serge; Microbiota
The geomorphological characteristics of the materials inherent in tropical soils, in addition to the excessive use of fertilizers and pesticides, industrial waste and residues, and novel pollutants derived from emerging new technologies such as nanomaterials, affect the functionality and resilience of the soil-microorganism-plant ecosystem; impacting phytoremediation processes and increasing the risk of heavy metal transfer into the food chain. The aim of this review is to provide a general overview of phytoremediation in tropical soils, placing special emphasis on the factors that affect this process, such as nanoagrochemicals, and highlighting the value of biodiversity among plant species that have the potential to grow and develop in soils impacted by heavy metals, as a useful resource upon which to base further research

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