Search

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

The genus Physalis includes species used for food, medicinal and artisanal purposes. The wild tomato (Physalis angulata L.), which is common in the mixed maize cultivation called "the milpa", is cultivated in some localities of Jalisco because of its importance in the preparation of sauces. It is hypothesized that the management of planting density and fertilization application can improve the yield of this tomato. The objective of this study was to evaluate the leaf area and yield of P. angulata L. as a function of slow-release urea doses and planting densities, under open-field rainfed conditions. Nine treatments were evaluated, resulting from the combination of three planting densities and three fertilizer doses. The experimental design was randomized complete blocks with factorial arrangement. The data were analyzed with analysis of variance and the means of the treatments were compared with Tukey's test (p = 0.05). The relationship between yield and study variables was estimated with simple linear regressions. The results indicated that with 2.5 plants m-2 the highest yield was obtained (6.4 Mg ha-1); while with 140 units of slow-release urea the average yield was 5.76 Mg ha-1. The interaction effect showed that with densities of 2.0 and 2.5 plants m-2 and with 120 kg of slow-release urea, the highest fruit yields were obtained, 6.44 and 6.87 Mg ha-1. For each unit increase in the variables leaf area, leaf area index, number of fruits per plant and fruit weight per plant, fruit yield increased as well. The yield of P. angulata responded differently to planting densities and slow-release urea doses. The best yield could be obtained with the planting density of 2.5 plants m-2 and with the application of 30.4 g m-2 slow-release urea. [ABSTRACT FROM AUTHOR]

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

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

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

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

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

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 H2SO4 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. [ABSTRACT FROM AUTHOR]

Tomatoes are commercially important worldwide for the ways it is consumed and its nutritional value. Due to its demand, cultivars with improved agronomic attributes, resistance to mechanical damage and longer shelf life have been developed. In certain cases, this has been achieved in detriment of organoleptic or nutritional quality, which native populations maintain. For this study, out of a collection of 600 native populations 13 were selected for their suitable agronomic characteristics for greenhouse cultivation, adequate yield and fruit size. Our objective was characterizing their chemical attributes related to taste and assessing their ascorbic acid content and compared it to two commercial hybrids. Our hypothesis was that the ascorbic acid and citric acid content, pH and total soluble solids in the fruits confer significant differences to the flavor. The experimental design was completely randomized, with 15 treatments and four repetitions. The data analysis was multivariate. In four stages of fruit maturity, pH, ascorbic acid, citric acid and total soluble solids content were quantified. The flavor components and the ascorbic acid content allowed three groups identification, one commercial hybrid with low ascorbic acid content, another with three native samples and the "Daniela" hybrid, classified as very sweet; and the one that included the "Sun7705" hybrid and five native samples classified as sweet, three native samples with neutral flavor and two tasteless. This confirms that native populations have potential to produce fruit for fresh or processed consumption and gourmet dishes. [ABSTRACT FROM AUTHOR]

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

Pulque bread is a traditional Mexican product that results from the fermentation by lactic acid bacteria (LAB) present in pulque or in its sediments (xaxtle). The objective of this study was to evaluate xaxtle as a starter culture in the fermentation of bread dough in order to obtain a low glycemic index baked product. Phenotypic and genotypic tests are used to identify bacteria of the genus Lactobacillus and yeasts of the genus of Saccharomyces as predominant organisms in xaxtle. Surface response methodology was used to obtain the optimum amount of lyophilized xaxtle, 3 g (~108 UFC·g-1) and the optimum time (90 min) of fermentation of the dough, considering the value D-optimum of the software Design Expert. The microstructure of the bread dough fermented with xaxtle showed a partial hydrolysis of the protein matrix, conformed by gliadins and glutenins. Furthermore, the total starch content and available starch of the bread with xaxtle decreased by 9.8% with respect to the bread made with S. cerevisiae (p=0.03) and the resistant starch was similar in both products (p=0.073). Fermentation with xaxtle reduced the hydrolyzed starch content in bread by approximately 4 %, thus classifying the product as low glycemic index bread. Therefore, the use of xaxtle as a starter culture in the fermentation of bread dough favored the reduction of the glycemic index due to the action of the microorganisms present. [ABSTRACT FROM AUTHOR]

Los elementos transponibles se usan como herramienta de mutagénesis insercional en plantas, por ejemplo, el sistema de transposones de maíz Ac (Activator) y Ds (Dissociation). Estos elementos se modificaron para facilitar la transposición en Arabidopsis thaliana con lo cual es posible el etiquetamiento y la clonación de genes. Esta herramienta se usa principalmente en la biología del desarrollo de plantas, generando marcadores específicos de tejidos y células, y su potencial se amplía en estudios de estrés biótico, como la infección por fitopatógenos como los geminivirus. El objetivo de este estudio fue usar trampas génicas como metodología para identificar genes que responden a la infección del virus de la hoja enrollada de la col (Cabbage leaf curl virus, CaLCuV) en plantas de A. thaliana. Para realizar el estudio se usaron 273 líneas transposantes Mexican Gene Trap (MGT) y 233 Mexican Enhacer Trap (MET). Las plántulas se bombardearon con el clon infeccioso de CaLCuV, y después fueron teñidas histoquímicamente para la detección de la expresión del gen reportero uidA (GUS) a 1, 3, 5 y 7 d después de la infección. Uno de los genes identificados fue PGM que codifica para una fosfoglicerato/bifosfoglicerato mutasa y tiene una respuesta temprana y específica de tejido en la infección de A. thaliana con CaLCuV. Para evaluar la función del gen PGM durante la infección, se generó una línea sobreexpresante. Los resultados sugieren que la sobreexpresión de PGM favorece la velocidad de aparición de síntomas; sin embargo el porcentaje de infección es muy bajo. El empleo de trampas génicas permite un escrutinio masivo, tejido-específico y en tiempo real durante la infección, por lo cual es una alternativa para la identificación inicial de genes del hospedero que responden a la infección por geminivirus. [ABSTRACT FROM AUTHOR]

Transposable elements are used as insertional mutagenesis tools in plants, for example, the transposons of maize Ac (Activator) and Ds (Dissociation). These elements were modified to facilitate transposition in Arabidopsis thaliana with which gene tagging and cloning became possible. This tool is used mainly in biology of plant development, generating specific markers for tissues and cells. Its potential is broadening in studies of biotic stress caused by infection with phytopathogens such as geminivirus. The objective of this study was to use gene traps as a method to identify genes that respond to the infection of the geminivirus Cabbage leaf curl virus, CaLCuV, in A. thaliana plants. To carry out the study, 273 Mexican Gene Trap (MGT) and 233 Mexican Enhacer Trap (MET) transposant lines were used. Seedlings were bombarded with an infectious CaLCuV clone and then stained histochemically to detect expression of the reporter gene UidA (GUS) 1, 3, 5 and 7 d post infection (dpi). One of the genes identified was PGM, which codes for phosphoglycerate/biphosphoglycerate mutase and has an early tissue-specific response to the infection of A. thaliana by CaLCuV. To evaluate the function of the PGM gene during infection, an over-expressing line was generated. The results suggest that over-expression of PGM favors the rate of symptom appearance. However, the percentage of infection is very low. The use of gene traps enables massive, tissue-specific screening in real time during the infection, making it an alternative for initial identification of host genes involved in the response to geminivirus infection. [ABSTRACT FROM AUTHOR]

The visual symptomatology of nutriment deficiencies, like iron (Fe) and manganese (Mn) in plant leafs is similar in their coloration and the kind of leaf they present on. A method based on the analysis of digital images of the leaves, capable to discriminate the differences of such deficiencies is required. The aim of this research was to analyze digital images of common bean (Phaseolus vulgaris L. var. Cacahuate), in order to identify differences in the Fe and Mn lesions in the initial development stage, when it is possible to revert damages with fertilization. To do so, we used a classifier created with probabilistic neuronal networks. The experimental treatments were: 1) partial deficiency (DP) of Fe (50 %); 2) DP of Mn (50 %); 3) total deficiency (DT) of Fe (0 %); 4) DT of Mn (0 %); 5) Fe/Mn interaction (0 % Fe, 0 % Mn); 6) control (100 % Fe, 100 % Mn), with 10 repetitions; Steiner solution was used as reference. The mean values of eight color and three texture variables from digital images of six common bean leaf samples were obtained; these were of 100×100 pixels (360 total samples) in 74 dds. These mean values were used as entry variables to generate the classifiers with a cascade correlation algorithm of the Fe and Mn deficiency treatments. The classifiers that only considered textural characteristics had correct global classification of symptoms less or equal to 44 %. In contrast, the highest percentage of correct global classification of the classifiers in the test was of 76.6 % with six variables, which included texture and color characteristics, and six exit classes of difference treatments. The reduction of the number of classes did not increase the percentage of correct classification in the test. [ABSTRACT FROM AUTHOR]

La sintomatología visual en hojas debida a deficiencias nutrimentales, como la de hierro (Fe) y manganeso (Mn), son similares en coloración y en tipo de hojas en que se presenta, por lo cual se requiere un método, con base en análisis de imágenes digitales de hojas, que discrimine esas deficiencias. El objetivo de esta investigación fue analizar imágenes digitales de hojas de frijol (Phaseolus vulgaris L.) var. Cacahuate para identificar, con un clasificador creado con redes neuronales probabilísticas, deficiencias de Fe y Mn en una etapa inicial, cuando todavía es posible revertir los daños con fertilización. Los tratamientos fueron: 1) deficiencia parcial (DP) de Fe (50 %); 2) DP de Mn (50 %); 3) deficiencia total (DT) de Fe (0 %); 4) DT de Mn (0 %); 5) interacción (0 % Fe, 0 % Mn); 6) testigo (100 % Fe, 100 % Mn), con 10 repeticiones; la referencia fue la solución Steiner. Los valores promedio de ocho variables de color y tres de textura, se obtuvieron de seis muestras de imágenes digitales de 100×100 píxeles (360 muestras en total), de hojas de frijol obtenidas 74 dds. Estas fueron usadas como variable de entrada para generar clasificadores con redes neuronales probabilísticas con el algoritmo de correlación en cascada de los tratamientos de deficiencias de Fe y Mn. Los clasificadores que solo consideraron características texturales, como variables de entrada, tuvieron porcentajes de clasificación correcta global de síntomas menores o iguales a 44 %. En cambio, el porcentaje de clasificación correcta global del mejor clasificador en la prueba fue 76.6 % con seis variables que incluyeron características de textura y color, y seis clases de salida o tratamientos de deficiencias. Un número menor de clases de salida no aumentó el porcentaje de clasificación correcta global en la prueba. [ABSTRACT FROM AUTHOR]

Plantas de chile Capsicum annuum L. CM334 exhiben un alto grado de resistencia a Phytophthora capsici, pero son susceptibles a Nacobbus aberrans; tal resistencia se ha asociado con la acumulación de capsidiol, una fitoalexina sesquiterpénica. En el presente estudio se determinó mediante qRT-PCR los niveles de expresión del gen HMG2 (hidroximetilglutaril- CoA reductasa 2, asociado con la biosíntesis de fitoalexinas sesquiterpénicas) en raíces de chile CM334 inoculadas con N. aberrans y en combinación con P. capsici. Los niveles de transcritos de HMG2 fueron significativamente reducidos (p⩽0.05) de -1.57 a -1.28 veces en la interacción CM334/ N. aberrans; mientras que en raíces inoculadas sólo con el oomiceto la acumulación de transcritos fue temprana e intensa (1.52 a 3.54 veces). En plantas inoculadas con ambos patógenos, la expresión fue alta comparada con aquellas inoculadas sólo con el nematodo (p⩽0.05), pero generalmente menor que la expresión observada en raíces inoculadas sólo con el oomiceto. La expresión del gen HMG2 (asociado con defensa) fue reducida en raíces de chile CM334 infectadas por N. aberrans. [ABSTRACT FROM AUTHOR]

Plants of chilli Capsicum annuum L. CM334 show a high level of resistance to Phytophthora capsici, but are susceptible to Nacobbus aberrans; such resistance has been associated with capsidiol accumulation, a sesquiterpene phytoalexin. In the present study the expression of hydroxymethylglutaryl- CoA reductase 2 gene (HMG2, associated with sesquiterpene phytoalexins biosynthesis) in CM334 chilli roots inoculated with N. aberrans and in combination with P. capsici, was determined by qRT-PCR. The levels of HMG2 transcripts were significantly reduced (p⩽0.05) from -1.57 to -1.28- fold in the interaction CM334/N. aberrans; whereas in roots inoculated only with the oomycete, the accumulation of transcripts occurred earlier and at higher levels (1.52 to 3.54-fold). In plants inoculated with both pathogens, the expression was higher compared with those inoculated with the nematode only (p⩽0.05), but generally lower than the expression observed in roots of plants inoculated with the oomycete alone. The expression of the HMG2 gene associated with defense was reduced in CM334 chilli plants infected by N. aberrans. [ABSTRACT FROM AUTHOR]

Forest litter emits CO2 into the atmosphere, but there are few studies on the subject and it is important to generate this information to improve inventories of greenhouse gases (GHGs). Methods to quantify this emission are performed in situ during long periods of measurements and others require the use of high cost instruments; some measure the loss of organic matter over time and others are indirect and are based on measurements dependent on weather conditions. The aim of this study was to generate a standardized operation protocol (PEO, its Spanish acronym) to measure the CO2 emission potential of in vitro litter using a manometric respirometer (OxiTop OC110®) in a maximum time of 10 d incubation. Litter samples were collected in a Quercus spp forest in Tequexquinahuac, Estado de Mexico, at the beginning of 2012. The experimental design was completely randomized, treatments were incubations (25 °C) with four litter moisture percentages (20, 40, 60 and 80% dry weight) and four sample sizes (5, 10, 20, 40 g), and each treatment was replicated three times. Based on the data ANOVA was performed and treatment means were compared with the Tukey test (p≤0.05). The response variables were: CO2 emission, CO2 emission rate and percentage of oxidized carbon compared to total carbon at the start of incubation. The optimum conditions for the measurement were 10 g sample and 60% humidity. Under these conditions the maximum CO2 emission was recorded (23554 mg CO2 kg-1) as well as the lowest standard deviation (331 mg CO2 kg-1), the lowest of the 16 treatments resulting from combining sample sizes and moisture percentage. In these conditions the percentage of carbon emitted compared to the initial carbon was the highest (5.26%). The measurement of respiration in such assay depends on the humidity of the sample and the availability of oxygen present in the system, which is the condition for determining the optimal operating environment using the OxiTop OC. The data generated by OxiTop are indicators of the potential emission of CO2 by different types of litter and have a similar value to that of the incubations performed to evaluate the potential mineralization of nitrogen. [ABSTRACT FROM AUTHOR]

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

Exogenous fibrolytic enzymes are not synthesized by the ruminal microorganisms, so they are added to feed in order to increase fiber degradation. The objective of this study was to evaluate in vitro xilanase, cellulose and laccase activity, as well as xylanase and cellulose enzymatic stability of an enzymatic fibrolytic product (Fibrozyme Alltech, Inc.). The experimental design was completely randomized and treatments were: buffer pH 6.0, buffer pH 7.0 and clarified ruminal fluid pH 6.5. Data were analyzed using the SAS Mixed procedure and the Tukey test (p≤0.05). The exogenous enzyme product contained 292 IU xylanase g-1 and 36 IU cellulase g-1, without laccase activity. In buffer with pH 6 cellulases were more stable than the xylanases, and both enzymes showed activity until 46 h. The speed constants of enzymatic inactivation (k) were -0.054 h-1 in xylanases and -0.008 h-1 in cellulases, and half life time (t1/2) of 12.8 and 87.7 h. In buffer pH 7 cellulases remained more stable and the xylanases lost their activity at 32 h; values of k were -0.07 h-1 and ?0.009 h-1, and t1/2 of 9.9 and 77 h for xylanases and cellulases. In the medium with clarified ruminal fluid, cellulases maintained more stable their activity and xylanases lost it in 4 h (k=-1.815 h-1 and -0.026 h-1; t1/2=0.38 and 26.87 h for xylanases and cellulases). It is concluded that in vitro pH and enzymes contained in the clarified ruminal fluid affect the stability of the exogenous fibrolytic enzyme product. [ABSTRACT FROM AUTHOR]