Carlos Ceceña-Duran

Molecular identification of phosphate-solubilizing native bacteria isolated from the rhizosphere of Prosopis glandulosa in Mexicali valley.

One of the main limitations in intensive crop production in Northwestern Mexico is the dependence on the use of phosphate fertilizer. In this study, we isolated indigenous microorganisms with phosphate solubilization capacities from mesquite (Prosopis glandulosa) present in the Mexicali valley. In total, 4 bacteria were isolated from the rhizosphere of mesquite, including ICA01, ICA02Ba, ICA03Bs, and ICA04Ma. The bacterial isolates were identified based on their phenotypic and 16S rRNA gene sequencing data to be Acinetobacter calcoaceticus. The results showed that ICA01 was the most efficient in solubilizing phosphate, followed by ICA02Ba and ICA03Bs, while ICA04Ma showed the lowest phosphate-solubilizing activity. The pH value of the culture medium decreased with bacterial growth, suggesting that these strains produce organic acids that solubilize phosphorus. These results will be useful for biotechnological studies and A. calcoaceticus may be employed for biofertilization programs in northwest Mexico.

Silver nanoparticles from Prosopis glandulosa and their potential application as biocontrol of Acinetobacter calcoaceticus and Bacillus cereus

Abstract In the present study the characterization and properties of silver nanoparticles from Prosopis glandulosa leaf extract (AgNPs) were investigated using UV–Vis spectroscopic techniques, energy dispersive X-ray spectrometers (EDS), zeta potential and dynamic light scattering. The UV–Vis spectroscopic analysis showed the absorbance peaked at 487 nm, which indicated the synthesis of silver nanoparticles. The experimental results showed silver nanoparticles had Z-average diameter of 421 nm with higher stability (−200 mV). The EDS analysis also exhibited presentation of silver element. Additionally, the different concentrations of AgNPs (25, 50, 75 and 100 mg/mL) showed antibacterial activity against Acinetobacter calcoaceticus and Bacillus cereus. Finally, AgNPs from leaf extracts of P. glandulosa may be used as an agent of biocontrol of microorganism of importance medical. However, further studies will be needed to fully understand the antimicrobial activity of silver nanoparticles obtain from P. glandulosa.

Bioaccumulation and effect of cadmium in the photosynthetic apparatus of Prosopis juliflora

Abstract In the present study Prosopis juliflora plants grown in hydroponics solution were exposed to 50,100 and 1000 μM CdCl2. The cadmium uptake, transport and toxicity on the photosynthetic activities in the plants were measured at 48 h after starting cadmium treatments. The results showed that the concentration of Cd2+ in P. juliflora tended to increase with addition of Cd2+ to hydroponics solution. However, the increase of Cd2+ in roots and leaves varied largely. In this sense, the accumulation of Cd2+ in P. juliflora roots increased significantly in proportion with the addition of this metal. In contrast a relatively low level of Cd2+ transportation index, and bioaccumulation factor were found in P. juliflora at 48 h after of treatments. On the other hand the maximum photochemical efficiency of photosystem II (Fv/Fm) and the activity of photosystem II (Fv/Fo) ratios in P. juliflora leaf treated with Cd2+ not showed significantly changes during the experiment. These results suggested that the photosynthetic apparatus of P. juliflora was not the primary target of the Cd2+ action. Further studies will be focused in understanding the participation of the root system in Prosopis plants with the rhizosphere activation and root adsorption to soil Cd2+ under natural conditions.

Efecto antifúngico de extractos fenólicos y de carotenoides de chiltepín (Capsicum annum var. glabriusculum) en Alternaria alternata y Fusarium oxysporum

The effect of phenolic and carotenoid extracts from chiltepin fruits on mycelial growth and the inhibition of conidial germination of Alternaria alternata and Fusarium oxysporum were investigated in the present work. Phenolic extracts inhibited mycelial growth of A.alternata by 38.46%, and significantly reduced conidial germination on the fifth day after treatment to 92% in relation to control. No significant changes were observed in the inhibition of mycelial growth in Fusarium oxysporum; however, the number of germinated conidia was reduced, showing 85% inhibition five days after treatment in relation to control. Moreover, carotenoid extracts showed 38.5% inhibition of mycelial growth and 85.3% inhibition of conidial germination of A.alternata, five days after treatment. Carotenoid extracts showed less inhibition of mycelial growth (20.3%) in F.oxysporum, with respect to A.alternata; while there was greater inhibition of conidial germination (96%) on the fifth day after treatment. Phenolic and carotenoid extracts from chiltepin may be a promising alternative as a natural fungicide against fungi of agricultural importance.

Effects of cadmium on total phenolic compounds and flavonoids in Euglena gracilis

En el presente estudio la produccion de compuestos fenolicos y flavonoides producidos por E. gracilis expuesto a dos concentraciones de cadmio fue evaluado usando cromatografia liquida de alta precision (HPLC). Los resultados mostraron que 0.02 mM de Cd+2 incrementaba significativamente el contenido total de compuestos fenolicos (798.46 ± 12.61 μg GA/g) y flavonoides (241.34 ± 47.63 μg QE/g) con respecto al control (137.34 ± 19.80 μg QE/g DW y 549.00 ± 8.57 μg GA/g DW) respectivamente. Sin embargo, incrementos no significativos en el contenido de compuestos fenolicos (568.54 ± 17.42 μg GA/g DW) y flavonoides totales (141.11 ± 9.36 μg QE/g DW) fueron observados en E. gracilis expuestas a 0.14 mM de Cd+2. Futuros estudios son necesarios para determinar la funcion especifica de los flavonoides en E. gracilis expuesto a altas concentraciones de Cd+2.

Changes in the phenylalanine ammonia lyase activity, total phenolic compounds, and flavonoids in Prosopis glandulosa treated with cadmium and copper

The aim of the present work is to evaluate the changes on the phenylalanine ammonia lyase (PAL) activity, phenolic compounds accumulation and photochemical efficiency in leaves of P. glandulosa treated with Cd2+ (0.001 M) and Cu2+ (0.52 M) concentrations for 96 h under hydroponic conditions. The results showed that only leaves treated with copper had a decrease in photochemical efficiency and leaf epidermal polyphenols in P. glandulosa leaves after 96 h of exposure. On the other hand the reverse-phase HPLC analysis revealed higher levels of phenolic compound (gallic, vanillic and caffeic acids) and flavonoids (rutin and kaempferol-3-O-glucosides) in plant leaves from Cu and Cd-treatments with respect to control plants. Finally, highest increments in PAL activity was observed in extracts of leaves treated with Cu and Cd (about 205 and 284%), respectively, with respect to control plants after 96 h treatment. These suggest that activation of phenylpropanoid pathway represent a source of nonenzymatic antioxidants that protect at P. glandulosa against oxidative stress when exposed to cadmium and copper. Hence future studies are necessary to elucidate the participation of phenylpropanoid pathway in the reduction of metal toxicity in Prosopis species.

Inoculación de Trichoderma longibrachiatum en algodón transgénico: Cambios en compuestos fenólicos y enzimas de estrés oxidativo

espanolEl objetivo del presente estudio fue evaluar la actividad de las enzimas fenilalanina amonio-liasa (PAL), peroxidasa (POX) y la produccion de compuestos fenolicos y flavonoides en plantas de algodon transgenico en respuesta a la inoculacion con Trichoderma longibrachiatum (ICA-4). Noventa dias despues de la inoculacion con T. longibrachiatum, hojas de las plantas de algodon fueron colectadas y las enzimas PAL, POX y los compuestos fenolicos fueron determinados. Los resultados mostraron que la inoculacion aumento el contenido de compuestos fenolicos y flavonoides en 18% y 45%, respectivamente; comparadas con plantas no inoculadas. La actividad de las enzimas peroxidasa (4,88 Ux10-5/mg de proteina), y fenilalanina amonia-liasa (0,0176 U/mg de proteina) mostraron diferencias significativas en comparacion con la actividad enzimatica de plantas no inoculadas (3,48x10-5 U/mg proteina para POX y 0,01 U/mg de proteina para PAL). Estos resultados sugieren la induccion de una respuesta de resistencia sistemica inducida por la inoculacion de las semillas con la cepa Trichoderma ICA-4. EnglishThe objective of the present study was to evaluate the activity of phenylalanine ammonia-lyase (PAL), peroxidase (POX) and the production of phenolic compounds and flavonoids in transgenic cotton plants in response to inoculation with Trichoderma longibrachiatum (ICA-4). Ninety days after inoculation with T. longibrachiatum, leaves of the cotton plants were collected and the enzymes PAL, POX and phenolic compounds were determined. The results showed that inoculation increased the content of phenolic compounds and flavonoids by 18% and 45%, respectively, compared to non-inoculatedplants. The activity of the enzymes peroxidase (4.88 Ux10-5/mg protein), and phenylalanine ammonia-lyase (0.0176 U/mg protein) showed significant differences compared to the enzymatic activity of uninoculated plants (3, 48x10-5 U/mg proteinfor POX and 0.01 U/mg proteinfor PAL). These results suggest the induction of a systemic resistance response induced by seed inoculation with the Trichoderma ICA-4 strain.

Expression of metallothionein type 2 and 3 genes in Prosopis glandulosa leaves treated with copper

For a better understanding of the strategies that are used by Prosopis glandulosa in heavy metal tolerance, the present study evaluated the gene expression of three metallothioneins (MTs; PgMt2-1, PgMt2, and PgMt3) in plants exposed to sub-lethal concentrations of copper. The PgMt2-1, PgMt2, and PgMt3 sequences were homologous to the MT type 2 (isoform 1), Mt2, and Mt3 sequences of other plant species found in GenBank. A reverse transcriptase-polymerase chain reaction showed that treatment with 100 mM Cu2+ induced a significant increase in PgMt2 and PgMt3 expression during the first 4 h of exposure compared to that of PgMt2-1. However, after 8 h of exposure, the expression levels of PgMt2 and PgMt3 were significantly lower than those of PgMt2-1. PgMt transcript levels only increased significantly during the first hour after exposure to copper, suggesting that PgMts could play a key role in the plants detoxification mechanism. However, additional studies are required to confirm MTs as a mechanism of heavy metal tolerance and accumulation in this species.

Changes of photochemical efficiency and epidermal polyphenols content of Prosopis glandulosa and Prosopis juliflora leaves exposed to cadmium and copper

Abstract The effect of metals on the photosynthetic activities and epidermal polyphenol content of Prosopis glandulosa and Prosopis juliflora leaves was investigated by the tissue tolerance test. Foliar tissues of Prosopis glandulosa and Prosopis juliflora were incubated with Cd2+ (0.001 M) or Cu2+ (0.52 M) concentrations for 96 h. The results showed that significant reductions (p < 0.05) of photochemical efficiency in P. juliflora leaves were found after 96 h of exposure to 0.52 M Cu2+ compared with Cd-treatments and controls. In contrast, P. glandulosa leaves showed a progressive increase on photochemical efficiency at 72 h after Cu-treatment. The results also showed a significant decrease (p < 0.05) of epidermal polyphenols in P. juliflora leaves after 24 h of exposure to 0.52 M Cu2+ compared with Cd-treatments and control leaves. On the other hand, the values of leaf epidermal polyphenols observed in P. glandulosa exposed to copper and cadmium did not show any difference with respect to control. These findings are very important and suggest that these compounds could be considered as a protection mechanism of P. glandulosa when is treated with these heavy metals. Finally, the results of bioaccumulation showed that the copper concentration in P. glandulosa was higher than the values detected in P. juliflora Nevertheless, the cadmium concentration in foliar tissues of P. juliflora was significantly higher than P. glandulosa after 96 h of exposure to Cu2+ or Cd2+. Therefore, future studies are necessary to elucidate the effects of heavy metals on the biosynthesis of flavonoids and participation of these compounds in the reduction of metal toxicity in Prosopis species.

El injerto como alternativa para mejorar el rendimiento en la producción de frijol ejotero (Phaseoulus vulgaris L.)

El ejote es una hortaliza que forma parte de la dieta basica en Latinoamerica, sin embargo, su produccion se ve frenada por diversos factores y el sector productivo demanda nuevas alternativas para el manejo de enfermedades y para el aumento en los rendimientos de las variedades. El objetivo del presente fue evaluar el rendimiento de dos variedades de frijol ejotero injertadas sobre dos variedades de frijol ayocote (Phaseolus coccineous) como portainjerto. El injerto fue de tipo empalme y su prendimiento se determino a los 20 dias. A los 7, 21 y 56 dias despues del trasplante se midio altura de planta. En cosecha se cuantifico numero de vainas, longitud de vaina y rendimiento por planta. Los resultados del porcentaje de prendimiento mostraron una temprana compatibilidad en la mayoria de los tratamientos a excepcion del tratamiento FXO, que no presento respuesta ante el injertado. Los tratamientos injertados aumentaron en 67,9% la longitud de las plantas en comparacion con las plantas no injertadas, el tamano de fruto y el rendimiento tambien se incremento en 50 y 100%, respectivamente. El frijol ejotero injertado en frijol ayocote representa una alternativa para mejorar el rendimiento y calidad del fruto.