Photosynthetic Traits of Páramo Plants Subjected to Short-Term Warming in OTC Chambers.

Global warming and changes in land use are some of the main threats to high mountain species. Both can interact in ways not yet assessed. In this study, we evaluated the photosynthetic responses of six common páramo species within a warming experiment using open-top chambers (OTC) in conserved páramo areas with different land use histories. We did not find significant differences in the photochemical performance of the species as measured through Fv/Fm, ETR, and NPQ in response to passive warming, indicating that warmed plants are not stressed. However, NPQ values were higher in recovering areas, especially in the driest and warmest months. Leaf transpiration, stomatal conductance, and Ci were not affected by the OTC or the land use history. The photosynthetic capacity, maximum photosynthetic capacity, and carboxylation rate of RuBisCO increased in response to warming but only in the area with no anthropogenic intervention. These results suggest that species will respond differently to warming depending on the history of páramo use, and therefore not all páramo communities will respond equally to climate change. In disturbed sites with altered soil conditions, plants could have a lower breadth of physiological response to warming.

Close-Range Thermography and Reflectance Spectroscopy Support In Vitro and In Vivo Characterization of Colletotrichum spp. Isolates from Mango Fruits.

Colletotrichum causing anthracnose in mango is known for its variable virulence that may have an effect on disease development and efficacy of management strategies. In this study, we characterized Colletotrichum spp. isolated from mango fruits under in vitro and in vivo conditions using close-range thermography and reflectance spectroscopy. Twenty-six isolates were phylogenetically characterized to ascertain species using the internal transcribed spacer sequence. Virulence, spectral (in vivo and in vitro), and thermographic responses (in vivo) of these isolates were analyzed. Isolates were grouped into the Colletotrichum gloeosporioides species complex and classified into eight morphotypes. Mycelial growth, conidia production, sporulation abundance, and area under disease progress curve (AUDPC) varied largely among isolates. Disease symptoms were observed 4 days after inoculation (dai), and, for most morphotypes, changes in tissue temperature were registered at 11 dai, with the greatest decrease at 14 dai with pathogen sporulation. In vitro and in vivo morphotypes shared changes in the spectrum range, and main variations were found in the number of informative spectral bands. In vivo average gross reflectance was higher in disease-inoculated tissue than in healthy uninoculated tissue. Morphotype responses varied depending on AUDPC values and postinoculation time. Discriminant analysis of the spectral response using principal component analysis and partial least squares regression explained 94 to 96.3 and 98 to 99.9% of the variance from in vitro and in vivo tests, respectively. Spectral markers were obtained for four distinct morphotype groups. We found three (550 to 650, 650.1 to 790, and 1,300 to 1,400 nm) and two (520 to 830 and 1,100 to 1,450 nm) regions with highly (P < 0.05) discriminant spectral bands for diseased fruits and morphotype characterization.

Prediction model for sap flow in cacao trees under different radiation intensities in the western Colombian Amazon.

In this study, we measured diurnal patterns of sap flow (Vs) in cacao trees growing in three types of agroforestry systems (AFs) that differ in the incident solar radiation they receive. We modeled the relationship of Vs with several microclimatic characteristics of the AFs using mixed linear models. We characterized microclimatic variables that may have an effect on diurnal patterns of sap flow: air relative humidity, air temperature, photosynthetically active radiation and vapor pressure deficit. Overall, our model predicted the differences between cacao Vs in the three different AFs, with cacao plants with dense Musaceae plantation and high mean diurnal incident radiation (HPAR) displaying the highest differences compared to the other agroforestry arrangements. The model was also able to predict situations such as nocturnal transpiration in HPAR and inverse nocturnal sap flows indicative of hydraulic redistribution in the other AFs receiving less incident radiation. Overall, the model we present here can be a useful and cost-effective tool for predicting transpiration and water use in cacao trees, as well as for managing cacao agroforestry systems in the Amazon rainforest.

Physiological, Biochemical and Yield-Component Responses of Solanum tuberosum L. Group Phureja Genotypes to a Water Deficit.

Water deficits are the major constraint in some potato-growing areas of the world. The effect is most severe at the tuberization stage, resulting in lower yield. Therefore, an assessment of genetic and phenotypic variations resulting from water deficits in Colombia germplasm is required to accelerate breeding efforts. Phenotypic variations in response to a water deficit were studied in a collection of Solanum tuberosum Group Phureja. A progressive water deficit experiment on the tuberization stage was undertaken using 104 genotypes belonging to the Working Collection of the Potato Breeding Program at the Universidad Nacional de Colombia. The response to water deficit conditions was assessed with the relative chlorophyll content (CC), maximum quantum efficiency of PSII (Fv/Fm), relative water content (RWC), leaf sugar content, tuber number per plant (TN) and tuber fresh weight per plant (TW). Principal Component Analysis (PCA) and cluster analysis were used, and the Drought Tolerance Index (DTI) was calculated for the variables and genotypes. The soluble sugar contents increased significantly under the deficit conditions in the leaves, with a weak correlation with yield under both water treatments. The PCA results revealed that the physiological, biochemical and yield-component variables had broad variation, while the yield-component variables more powerfully distinguished between the tolerant and susceptible genotypes than the physiological and biochemical variables. The PCA and cluster analysis based on the DTI revealed different levels of water deficit tolerance for the 104 genotypes. These results provide a foundation for future research directed at understanding the molecular mechanisms underlying potato tolerance to water deficits.

Seed Structural Variability and Germination Capacity in Passiflora edulis Sims f. edulis.

Purple passion fruit, Passiflora edulis Sims f. edulis, is an important semi-perennial, fruit bearing vine originating in South America that produces a commercial tropical juice pulp for international and national consumption. Within the round purple passion fruit are a large number of membranous seed sacs each containing individual seeds. Little is known about the seed anatomy of the commercial passion fruit, differences between wild collected and commercial types, and its effect on seedling germination. Therefore, our main objective for this study was to analyze the seed anatomy variability of different germplasm as well as the effect on viability and germination of the seeds of this species. Germplasm was evaluated from three sources: (1) commercial cultivars grown in current production areas, (2) genebank accession from the national seed bank, and (3) landraces collected across different high and mid-elevation sites of the Andean region. A total of 12 morphometric descriptors related to seed anatomy were evaluated on the 56 genotypes, of which three were most informative: Angle to the vertex which is related to the shape of the seed, the thickness of the tegument and the horizontal length; separating the seed according to its source of origin. Germination was found to be positively correlated with the number (r = 0.789) and depth (r = 0.854) of seed pitting. Seeds of the commercial cultivars had more seed pits and higher germination compared to seeds of landraces or genebank accessions showing a possible effect of domestication on the crop. Interestingly, passion fruits often germinate during the rainy season as escaped or wild seedlings especially in the disturbed landscapes of coffee plantations, so some dormancy is needed but faster germination is needed for intensive cultivation. Harnessing passion fruit diversity would be useful as the semi-domesticated landraces have valuable adaptation characteristics to combine with rapid germination selected in the commercial cultivars. The variability of seed pitting with cultivars more pitted than landraces possibly resulting in faster germination may indicate that purple passion fruit is still undergoing a process of selection and domestication for this trait.

Photosynthesis limitations in cacao leaves under different agroforestry systems in the Colombian Amazon.

Cacao (Theobroma cacao L.) has traditionally been considered a crop that requires shade, and consequently it is implemented under agroforestry systems (AFs) in order to regulate the level of incident solar radiation. However, optimal shade levels for this tree crop may vary depending on the climate conditions of where it is grown. Here we analyzed the physiological performance of cacao under three different AFs in the Colombian Amazon that differed in solar radiation patterns: high (HPAR), medium (MPAR), or low (LPAR) mean daily incident radiation. The physiological performance was characterized using photosynthetic variables in leaves such as light- and CO2-response curves, chlorophyll a fluorescence parameters, and total chlorophyll and carotenoid contents, in conjunction with other leaf functional traits. Cacao trees exposed to HPAR showed an improved physiological performance as compared to those from the other two AFs. Compared to MPAR and LPAR, cacao trees in HPAR doubled the rate of net carbon assimilation and reached higher maximum rates of RuBisCO carboxylation and RuBP regeneration. Moreover, cacao trees in HPAR presented photoprotection mechanisms that avoided photoinhibition, which was accompanied by a greater non-photochemical quenching coefficient and biochemical and morphological adjustments (low chlorophyll but higher carotenoid contents and low specific leaf area) compared to cacao trees from the other AFs. Overall, our results show that, due to the high cloud cover in the Colombian Amazon, cacao plantations under conditions of sparse shade maximized their carbon use, showing an improved physiological performance as a result of higher photosynthetic rates and energy dissipation mechanisms. If the crop were managed with sparse shade, the paradigm that favors the cultivation of cacao under shade would be called into question in the Colombian Amazon and other regions with similar climatic conditions.

First typology of cacao (Theobroma cacao L.) systems in Colombian Amazonia, based on tree species richness, canopy structure and light availability.

AIM AND BACKGROUND: We present a typology of cacao agroforest systems in Colombian Amazonia. These systems had yet to be described in the literature, especially their potential in terms of biodiversity conservation. The systems studied are located in a post-conflict area, and a deforestation front in Colombian Amazonia. Cacao cropping systems are of key importance in Colombia: cacao plays a prime role in post conflict resolution, as cacao is a legal crop to replace illegal crops; cacao agroforests are expected to be a sustainable practice, promoting forest-friendly land use. MATERIAL AND METHODS: We worked in 50 x 2000 m2 agroforest plots, in Colombian Amazonia. A cluster analysis was used to build a typology based on 28 variables characterised in each plot, and related to diversity, composition, spatial structure and light availability for the cacao trees. We included variables related to light availability to evaluate the amount of transmitted radiation to the cacao trees in each type, and its suitability for cacao ecophysiological development. MAIN RESULTS: We identified 4 types of cacao agroforests based on differences concerning tree species diversity and the impact of canopy spatial structure on light availability for the cacao trees in the understorey. We found 127 tree species in the dataset, with some exclusive species in each type. We also found that 3 out of the 4 types identified displayed an erosion of tree species diversity. This reduction in shade tree species may have been linked to the desire to reduce shade, but we also found that all the types described were compatible with good ecophysiological development of the cacao trees. MAIN CONCLUSIONS AND PROSPECTS: Cacao agroforest systems may actually be achieving biodiversity conservation goals in Colombian Amazonia. One challenging prospect will be to monitor and encourage the conservation of tree species diversity in cacao agroforest systems during the development of these cropping systems, as a form of forest-friendly management enhancing sustainable peace building in Colombia.

Substantial equivalence analysis in fruits from three Theobroma species through chemical composition and protein profiling.

Substantial equivalence studies were performed in three Theobroma spp., cacao, bicolor and grandiflorum through chemical composition analysis and protein profiling of fruit (pulp juice and seeds). Principal component analysis of sugar, organic acid, and phenol content in pulp juice revealed equivalence among the three species, with differences in some of the compounds that may result in different organoleptic properties. Proteins were extracted from seeds and pulp juice, resolved by two dimensional electrophoresis and major spots subjected to mass spectrometry analysis and identification. The protein profile, as revealed by principal component analysis, was variable among the three species in both seed and pulp, with qualitative and quantitative differences in some of protein species. The functional grouping of the identified proteins correlated with the biological role of each organ. Some of the identified proteins are of interest, being minimally discussed, including vicilin, a protease inhibitor, and a flavonol synthase/flavanone 3-hydroxylase. BIOLOGICAL SIGNIFICANCE: Theobroma grandiflorum and Theobroma bicolor are endemic Amazonian plants that are poorly traded at the local level. As close relatives of Theobroma cacao, they may provide a good alternative for human consumption and industrial purposes. In this regard, we performed equivalence studies by conducting a comparative biochemical and proteomics analysis of the fruit, pulp juice and seeds of these three species. The results indicated equivalent chemical compositions and variable protein profiles with some differences in the content of the specific compounds or protein species that may result in variable organoleptic properties between the species and can be exploited for traceability purposes.

MEDICIÓN DE LA FLUORESCENCIA DE LA CLOROFILA a EN ALGAS ENCAPSULADAS EN ALGINATO DE CALCIO / Measuring of the Chlorophyll a Fluorescence in Calcium Alginate-Encapsulated Algae

RESUMEN La inmovilización de las algas tiene múltiples aplicaciones, tales como la biorremediación del agua y la producción de metabolitos. Una de las variables que se puede determinar en las algas inmovilizadas es la fluorescencia de la clorofila a, debido a que este parámetro está relacionado con la respuesta fisiológica de estos organismos. Por ello, el objetivo de este estudio fue explorar un método para la medición de la fluorescencia de la clorofila a en algas encapsuladas en esferas de alginato de calcio. Con este fin, se cultivaron dos especies de microalgas (Scenedesmus ovalternus LAUN 001 y Parachlorella kessleri LAUN 002) en monocultivos, tanto en condiciones de cultivo libres (10 mL de la preparación algal en 250 mL de Medio Básico de Bold), como encapsuladas (250 esferas de alginato de calcio en 250 mL de Medio Básico de Bold). Se realizaron diferentes protocolos de medición de la fluorescencia de la clorofila a del fotosistema II (PSII) variando a) el tiempo de preadaptación a la oscuridad (10, 15 y 30 min), b) la intensidad de luz generada por fluorómetro no modulado (entre 1000 y 3500 -jmoles m-2 s-1), y c) el tiempo de exposición a la luz actínica (1, 2 y 5 s). Se lograron establecer como condiciones óptimas para la medición de la eficiencia cuántica potencial del fotosistema II (Fv/Fm) en las algas encapsuladas las siguientes: a) 30 min de preadaptación a la oscuridad; b) 3000 -jmoles m-2 s-1, de intensidad lumínica generada desde el fluorómetro; y c) 1 o 2 s de exposición a la luz actínica. Se encontraron los siguientes valores en la Fv/Fm en condiciones no estresantes: 0,760 a 0,764 para S. ovalternus y 0,732 a 0,748 para P. kessleri. Esta metodología permite observar algunos cambios en la actividad fotoquímica relacionados con variaciones de los factores bajo los cuales se encuentran las algas inmovilizadas.

ABSTRACT Immobilization of algae has many applications, such as water bioremediation and production of metabolites. One of the variables that can be determined in the immobilized algae is chlorophyll a fluorescence, because this parameter is related to the physiological response ofthese organisms. Therefore, the objective ofthis study was to explore a method for measuring the chlorophyll a fluorescence in calcium alginate-encapsulated algae. To do this, two species of microalgae (Scenedesmus ovalternus LAUN 001 and Parachlorella kessleri LAUN 002) were grown in monocultures in both free culture conditions (10 mL of algae preparation in 250 mL of Basal Bold Medium) and encapsulated (250 spheres in 250 mL of Basal Bold Medium). Different measurement protocols of chlorophyll a fluorescence of photosystem II (PSII) were performed by varying a) the preadaptation time to darkness (10, 15 and 30 min), b) the light intensity of the non-modulated fluorometer (between 1000 and 3500 Llmoles m-2s-1), and c) the time of exposure to actinic light (1, 2 and 5 s). The optimal conditions for the measurement of the maximum quantum yield ofPSII (Fv/Fm) in encapsulated algae were established as follow: a) 30 min of preadaptation time; b) 3000 Llmoles m-2s-1 of the fluorometer light intensity; and c) 1 to 2 s of exposure to actinic light. The following values in the photochemical activity of algae in non-stressful conditions were found: 0.760 - 0.764 for S. ovalternus, and 0.732 - 0.748 for P. kessleri. This methodology allows to observe some changes in the photochemical activity related with variations in the factors under which are the immobilized algae.

Photosynthetic performance and leaf water potential of gulupa (Passiflora edulis Sims, Passifloraceae) in the reproductive phase in three locations in the colombian andes / Desempeño fotosintético y potencial hídrico foliar de gulupa (Passiflora edulis Sims, Passifloraceae) en estado reproductivo en tres localidades de los Andes colombianos

Gulupa, Passiflora edulis Sims (Passifloraceae), is an important fruit due to its organoleptic and nutritional characteristics and its demand in the international market; however, very few studies have been conducted for studying its Ecophysiology. Until now, this crop has spread throughout the country through empirical knowledge without data that indicate the zones that are more suitable for its cultivation. For this reason, gas exchange, chlorophyll fluorescence (photosystem II operating efficiency and maximum quantum efficiency of photosystem II photochemistry) and leaf water potential were measured in three different locations of Cundinamarca department (Chia [2610 m a.s.l., 14 °C], Granada [2230 m a.s.l., 15 °C] and Tena [2090 m a.s.l., 17 °C]), whose climatic conditions were monitored with meteorological stations to evaluate the physiologic performance in each location related to the environmental factors. The results indicate that, even though the photosynthetic capacity was similar and high in Granada and Tena, the water status of the plant, the stomatal control of water loss and recovery of photosystems during the night were more efficient in Granada (p < 0.05). In Tena, the small differences between day and night temperature, humidity, and vapor pressure deficit (VPD) would limited the night water recovery in the plants. Meanwhile, in Chia, the increase of VPD during the day and the low temperatures would decreased the water potential both during the day and during the night, as well as the recovery of photosystem II. Therefore, in conclusion the climatic conditions similar to Granada, which are 18/13 °C day/night, a VPD close to 0.5 KPa, and radiation that did not exceed 1000 μmol photons/m²s favored the good physiological performance of gulupa.

La gulupa, Passiflora edulis Sims (Passifloraceae) es un frutal importante debido a sus características organolépticas, nutricionales y su demanda en el mercado internacional; sin embargo, existen muy pocos estudios relacionados con su ecofisiología. Hasta el momento, el cultivo se ha extendido a través del país por medio de conocimiento empírico sin tener datos que sustenten las zonas más apropiadas para su cultivo. Por esta razón, en el presente estudio se midió el intercambio de gases, la fluorescencia de la clorofila (factor de eficiencia del fotosistema II y eficiencia cuántica fotoquímica máxima del fotosistema II) y el potencial hídrico foliar en tres localidades diferentes del departamento de Cundinamarca (Chía [2610 m s.n.m., 14 °C], Granada [2230 m s.n.m., 15 °C] y Tena [2090 m s.n.m., 17 °C]), cuyas condiciones climáticas fueron monitoreadas con estaciones meteorológicas para evaluar el desempeño fisiológico en cada localidad y relacionarlo con los factores ambientales. Los resultados indican que aunque la capacidad fotosintética fue alta y similar en Granada y Tena, el estado hídrico de la planta, el control estomático de la pérdida de agua y la recuperación de los fotosistemas durante la noche fueron más eficientes en Granada (p < 0,05). En Tena, la estrecha diferencia entre los valores día/noche de temperatura, humedad y déficit de presión de vapor (DPV) limitarían la recuperación hídrica de la planta, mientras que en Chía el aumento de DPV en el día, y las bajas temperaturas disminuirían el potencial hídrico, tanto durante el día como durante la noche, así como la recuperación del fotosistema II. Por tanto, en conclusión, condiciones climáticas cercanas a las de Granada; 18/13 °C día/noche, DPV de 0,5 KPa, y una radiación que no exceda los 1000 μmol fotones/ m²s favorecen el buen desempeño de la planta.

Variación temporal a Microcyclus ulei en los clones de caucho FX 3864 y FX 4098 en condiciones controladas / Temporal variation to Microcyclus ulei in rubber tree clones FX 3864 and FX 4098 under controlled conditions

Este estudio tuvo como objetivo evaluar la variación temporal de los principales componentes fisiológicos asociados a la reacción de dos clones (FX 3864 y FX 4098) de Hevea brasiliensis a Microcyclus ulei en condiciones controladas. Las inoculaciones se realizaron en cámara húmeda a 23 ºC, una humedad relativa superior al 90% y un fotoperíodo de 12 h. Con un modelo de medidas repetidas en el tiempo y mediante correlaciones se analizaron cuatro variables: severidad de ataque (SA), intensidad de esporulación conidial (IE), tamaño de lesión (TL) y frecuencia de infección (FI). M. ulei generó síntomas en los dos clones a los 4 días después de la inoculación. Los signos de la enfermedad (IE= 3) se manifestaron a los 8 días en el clon FX 3864 y a los 12 días en el clon FX 098. FX 3864 presentó la mayor susceptibilidad a M. ulei (mayor severidad y una esporulación alta, IE= 4). En general, se observó una influencia del tiempo en la reacción de cada clon para las variables SA, IE y TL. Altas correlaciones significativas se encontraron entre SA y las variables IE, TL y FI, excepto en el día 12 para IE. Este estudio permite concluir que en condiciones controladas la intensidad y la frecuencia de los síntomas así como el grado de esporulación producidos por M. ulei cambian significativamente a través del tiempo y esta variación está influenciada a su vez por el nivel de susceptibilidad a M. ulei presentado por cada clon de H. brasiliensis.

This study aimed to evaluate the effect of temporal variation on the main physiological components associated with the reaction to Microcyclus ulei of two rubber tree clones of Hevea brasiliensis under controlled conditions. Inoculations were performed in a moist chamber at 23 °C, a relative humidity higher than 90% and a photoperiod of 12 h. The variables severity of attack (SA), conidial sporulation intensity (IE), lesion size (TL) and infection frequency (IF) were analyzed with a repeated over time measurements model and also with correlations. M. ulei produced symptoms (SA, TL, FI) in both rubber tree clones 4 days after inoculation. Signs of the disease (IE = 3) appeared in the FX 3864 at day 8th and in the FX 4098 at day 12th. FX 3864 presented higher susceptibility to M. ulei (greater severity and high sporulation, with IE = 4). In general, the time influenced the reaction of each clone, especially in the variables SA, IE and TL. High significant correlations were found between SA and the variables IE, TL and FI, except on day 12 for IE. It was concluded that intensity and frequency of symptoms and the degree of sporulation produced by M. ulei change significantly over time under controlled conditions and this variation is influenced also by the level of susceptibility to M. ulei showed by each clone of H. brasiliensis.

Bioprospecting ss a possible development mechanism for Colombia / Bioprospección como posible mecanismo de desarrollo para Colombia

Bioprospecting has been on the agenda for discussion by the government, the academic community, businesses and other pertinent actors for many years now; it is an integral topic representing a potential approach to exploit biodiversity to the fullest. This document presents some definitions of what bioprospecting is (some restrictive, others with a broader perspective, depending on different approaches, actors, target markets and countries) in the context of a mechanism for development and cooperation concerning the construction of capacities, advantages and disadvantages. It was found that bioprospecting in Colombia has been developing from a broad perspective (systematic study of biological-genetic resources, transformation into a product which has led to strengthening some value chains, small- and/or large-scale marketing and some advances in intellectual property rights and the distribution of benefits) in order to provide greater benefits for the nation.

La bioprospección ha sido durante varios años tema de discusión por los gobiernos, la comunidad académica, las empresas, y otros actores que se integran en el proceso, como potencial de acercamiento y uso de la diversidad biológica. A través del presente documento se presentan algunas definiciones de lo que es la bioprospección (algunas restrictivas otras de perspectiva amplia, dependientes de diferentes aproximaciones, actores, blanco de mercado, contexto del país, entre otros), la bioprospección como mecanismo de desarrollo y cooperación para la construcción de capacidades, ventajas y desventajas. Se encuentra que en Colombia se ha venido desarrollando bioprospección desde la perspectiva amplia (estudio sistemático del recurso biológico-genético, transformación en un producto lo que ha permitido el fortalecimiento de algunas cadenas de valor, comercialización a pequeña o gran escala y algunos avances en temas de propiedad intelectual y distribución de beneficios) lo cual puede brindar mayores beneficios para la nación.

EFECTO DE LA LUZ Y DEL ÁCIDO GIBERÉLICO (AG3) EN LA GERMINACIÓN DE Minthostachys mollis KUNTH. GRISEB.(LABIATAE) / Effect of Light and Giberellic Acid (AG3) on the Germination of Minthostachys mollis Kunth. Griseb. (Labiatae)

Minthostachys mollis (Kunth) Griseb., es un arbusto perenne que crece en la región andina de Colombia; es ampliamente utilizada por las comunidades rurales donde es valorado por sus propiedades medicinales. El objetivo de este estudio fue determinar el efecto de la luz (luz roja, luz blanca y luz natural) y del ácido giberélico (0, 5, 15, 25 ppm) en el proceso de germinación de M. mollis. Se encontró inhibición de la germinación bajo condiciones de oscuridad. No se observó efecto de AG3 sobre la germinación. Los porcentajes de germinación fueron superiores a 80% para los tratamientos con luz (semilla fotoblástica positiva), donde el tratamiento con luz roja tuvo el efecto más significativo sobre el proceso de germinación.

Minthostachys mollis (Kunth) Griseb., is a perennial shrub that grows in the Andean region of Colombia; this species is widely used by rural communities where it is valued for its medicinal properties. The aim of this study was to determine the effect of light (red light, white light, and natural light) and gibberellic acid (0, 5, 15, 25 ppm) on the process of germination of M. mollis. We found a strong inhibition of germination under conditions of darkness. We do not observe effect of AG3 on germination. The germination percentages obtained were above 80% (positive photoblastic seeds) for the three proposed lighting treatments where red-light treatment had a most significant effect on the germination process.

Efecto de la incculación con hongos formadores e micorrizas arbusculares sobree plántulas de caucho / Effects Of Inoculation With Arbuscular Mycorrhizal Fungi On Rubber Seedlings

Hongos formadores de micorrizas arbusculares (HFMA) obtenidos a partir de suelos caucheros se multiplicaron en plantas de Lolium sp., con 73% de colonización radical luego de cuatro meses. Se obtuvieron siete morfotipos de HFMA, con los cuales se inocularon dos grupos de plántulas de Hevea brasiliensis: 1) producidas in vivo a partir de semilla; 2) producidas in vitro por rescate de embrión, para determinar efectos sobre mortalidad, crecimiento, micorrización y contenido de fósforo foliar. Los niveles de colonización por HFMA para las plántulas obtenidas in vitro e in vivo fueron de 12,6% y de 44,7%, respectivamente. La biomasa media total acumulada por las plántulas producidas in vitro fue de 0,41 y de 1,40 g por las procedentes del material in vivo, en comparación con los controles no inoculados, los cuales acumularon 0,37 y 0,40 g , respectivamente. El tratamiento con HFMA disminuyó la mortalidad en las plántulas obtenidas in vitro, aunque no tuvo un efecto significativo sobre el contenido de fósforo foliar. La respuesta del crecimiento de las plántulas inoculadas fue diferente dependiendo del origen del material vegetal y del tipo de inóculo (nativo o no nativo). La simbiosis entre HFMA y H. brasiliensis se desarrolló en condiciones controladas de crecimiento, aunque su avance dependió del estado de desarrollo de la plántula. No obstante, influyó en el crecimiento y en la disminución de la mortalidad de las plántulas, lo que abre la posibilidad de utilizarla como alternativa de inoculación en las fases tempranas de obtención del material vegetal.

Hevea brasiliensis rubber plants were inoculated with native arbuscular mycorrhizal fungi (AMF) during their greenhouse acclimatization. The AMF were multiplied for 4 months associated with Lolium sp. plants having 73% root colonization. Seven morphotypes were obtained. Two different groups of H. brasiliensis plants were inoculated with these morphotypes to determine AMF effect on mortality rate, growth, mycorrhization and leaf P content: those produced in vivo by seed germination and those produced in vitro by micropropagation. Plantlets produced in vitro returned 12.6% AMF colonization and 0.41 g accumulated dry biomass, whereas seedlings produced in vivo had 44.7% and 1.40 g , respectively, compared to control plants with no AMF inoculation which accumulated 0.37 g (in vitro) and 0.40 g (in vivo). AMF inoculation reduced the plants’ mortality rate regarding in vitro produced material; however, it did not influence foliar P content. Inoculated plants’ growth response was different, depending on plant material and the kind of inoculum used (native or foreign). Symbiosis developed between AMF and H. brasiliensis in controlled growth conditions although its advance was limited by the plants’ growth stage. Nevertheless, such association influenced inoculated plants’ biomass accumulation and decreased their mortality rate and could be used as an alternative treatment during the earliest stages of H. brasiliensis plantlet production.

Plasmodemos: estructura y funcion / Plasmodesmata: Structure and Function

Los plasmodesmos son canales que atraviesan la membrana y la pared celular. Estos canales especializados y no pasivos, actúan como compuertas que facilitan y regulan la comunicación y el transporte de sustancias como agua, nutrientes, metabolitos y macromoléculas entre las células vegetales. En los últimos años, una nueva visión sobre estos canales ha surgido y, estudios han demostrado que los plasmodesmos son más complejos de lo que anteriormente se pensaba. En esta nota, se pretende exponer el conocimiento actual sobre dichas estructuras, enfocándonos en su estructura y función.

Protein electrophoretic patterns and antifreezing activity in the leaf apoplast in the tropical andean species Senecio niveoaureus

Tropical high mountain plants have different adaptations to survive extreme daily temperature fluctuations and specially freezing night conditions. In winter plant species, survival to low temperatures is related to the ability of the cell to produce specific low molecular weight proteins (antifreezing proteins) and to export them to the apoplast. In order to see if high mountain tropical plants survive to low temperatures through the same mechanism we collected, during a 24 hourperiod, leaves from Senecio niveoaureus growing at 3,300 and 3,600 m.o.s.l, in the Páramo de Palacio, Chingaza, Colombia. Leaf apoplast proteins had MW between 3512 kDa. Electrophoretic patterns were different depending on the altitude and the time of sampling. However the observed variations could not be linked to changes in temperature or to the altitudinal gradient. Antifreeze activity was detected in leaf apoplast of plants at different altitudes. This is the first report of antifreeze activity in a high mountain tropical species.

Isozyme characterization of Capsicum accessions from the Amazonian Colombian collection / Caracterización por isoenzimas de accesiones de Capsicum pertenecientes a la colección amazónica colombiana

Two hundred and sixty-one accessions of the genus Capsicum were obtained from the Colombian Amazonian germplasm bank at Amazonian Institute of Scientific Research (Sinchi) and were evaluated with five polymorphic enzymatic systems, including esterase (EST), peroxidase (PRX), 6-phosphogluconatedehydrogenase (6-PGDH), aspartate amino transferase (GOT), and malic enzyme (ME). Using a cluster analysis (UPGMA) the genetic variability of these accessions were characterized. Grouping of the species C. baccatum and C. pubescens were observed, while the species C. annuum, C. chinense and C. frutescens did not group independently, a result that has been previously reported in isoenzyme analyses of this genus. Several accessions were deemed of particular interest for future ecological and evolutive studies.

Doscientas sesenta y una accesiones del género Capsicum del banco de germoplasma del Instituto Amazónico de Investigaciones Científicas (Sinchi) se evaluaron a través de cinco sistemas enzimáticos polimórficos: esterasa (EST), peroxidasa (PRX), 6-fosfogluconato deshidrogenasa (6-PGDH), aspartato amino transferasa(GOT) y enzima málica (ME). Se utilizó un análisis de agrupamiento (Upgma) con el fin de determinar la variabilidad genética. Se observó un agrupamiento de las especies C. baccatum y C. pubescens, mientras que las especies C. annuum, C. chinense y C. frutescens no mostraron un agrupamiento independiente, lo cual ya ha sido reportado en estudios por isoenzimas para el género. Varias accesiones mostraron característicasparticulares para estudios ecológicos y evolutivos.