COMPARACIÓN DE HUELLAS DE DNA EN HOJA Y FRUTO DE Capsicum spp.: INFERENCIA DE POLINIZACIÓN CRUZADA

The Capsicum genus comprehends five species that are mostly cultivated (C. annuum L., C. chinense Jacq., C. frutescens L., C. baccatum L. and C. pubescens). México occupies the second place in world production, with the C. annuum crop being of greater economic, cultural and social importance. DNA fingerprints in leaf and fruit of two varieties of C. annuum (Jalapeño and Serrano) and one variety of C. pubescens (Manzano) were compared with ISSR gene markers, in order to estimate the degree of crossing that took place in different environments in experimental plants. For each PCR primer, 32 to 44 amplicons were obtained, and in total 76 fragments of different molecular weights were considered to carry out the analyses. The PIC, MI and Rp values were 0.75, 0.70 and 18.8 for leaf, and de 0.67, 0.62 and 20 for fruit. With the Iso_1 primer the percentages of polymorphism obtained were 91.3 % for leaf and 87 % for fruit from the same plant. The ISSR markers allowed estimating the percentage of cross-pollination, thus comparing the genetic information of leaf and fruit structures in Capsicum spp., which can accelerate the plant improvement process, also permitting to differentiate the three pepper varieties, separate the cultivars and estimate the level of pollination that took place under experimental conditions.El género Capsicum comprende cinco especies mayormente cultivadas (C. annuum L., C. chinense Jacq., C. frutescens L., C. baccatum L. y C. pubescens). México ocupa el segundo lugar de producción mundial, en donde el cultivo de C. annuum es de mayor importancia económica, cultural y social. Se compararon huellas de DNA en hoja y fruto de dos variedades de C. annuum (Jalapeño y Serrano) y una variedad de C. pubescens (Manzano) con marcadores genómicos ISSR, para estimar el grado de entrecruzamiento ocurrido en diferentes ambientes en plantas experimentales. Se obtuvieron de 32 a 44 amplicones por iniciador para PCR y en total se consideraron 76 fragmentos de diferentes pesos moleculares para realizar los análisis. Los valores de PIC, MI y Rp fueron de 0.75, 0.70 y 18.8 para hoja, y de 0.67, 0.62 y 20 para fruto. Con el iniciador Iso_1 se obtuvieron porcentajes de polimorfismo de 91.3% para hoja y 87% en fruto de la misma planta. Los marcadores ISSR permitieron estimar el porcentaje de polinización cruzada, comparando la información genómica de estructuras de hoja y fruto en Capsicum spp., lo que puede acelerar el proceso de fitomejoramiento, permitiendo además, diferenciar a las tres variedades de chile, separar a los cultivares y estimar el nivel de polinización ocurrida en condiciones experimentales

CARACTERIZACIÓN E IDENTIFICACIÓN MOLECULAR DE BACTERIAS AISLADAS DE KEFIR

Kefir is a probiotic food composed mainly of lactic acid bacteria and yeasts; intake helps the proper function of the human intestine by increasing the beneficial flora. Depending on the geographic site, this product has distinctive organoleptic characteristics provided by the type of associated microorganisms and the quality of the milk used. Kefir has undergone industrialization, but to standardize the taste and quality, it is necessary to select the appropriate inoculum. Lactic acid bacteria isolated from artisanal kefir were identified and characterized molecularly. All the bacteria were rod shaped, Gram positive, catalase negative and with no sporulation; the bacteria also acidified the milk with different pH values. Thefermented milk showed viscous consistency, characteristic odor and most frequently it was gasified. Bacterial isolates were differentiated with RAPD and DAF-PCR, and classified into four groups. The sequences of the 16S gene identified them as Lactobacillus kefiri.El kefir es un alimento probiótico, compuesto principalmente de bacterias ácido-lácticas y levaduras. Su ingesta ayuda al buen funcionamiento del intestino humano por el incremento de la flora benéfica. Dependiendo del lugar, este producto presenta características organolépticas distintivas proporcionadas por el tipo de microorganismos asociados y la calidad de la leche utilizada. Actualmente existe interés en industrializarlo, pero es necesario seleccionar el inóculo adecuado para estandarizar su sabor y calidad. Con base en lo anterior, se caracterizaron e identificaron molecularmente bacterias ácido-lácticas aisladas de kefir artesanal. Todas las bacterias caracterizadas fueron de forma bacilar, Gram positivas, catalasa negativas, sin esporulación, y acidificaron la leche en valores de pH diferentes. La leche fermentada presentó consistencia viscosa, olor característico, y generalmente estaba gasificada. Todos los maislamientos fueron diferenciados con RAPDs, RAPD-CAFs, separados en cuatro grupos, y las secuencias del gen 16S los identificó como Lactobacillus kefiri

Genetic and Molecular Characterization of Temperate and Tropical Forage Maize Inbred Lines

Livestock feeding in the Central highland of Mexico is based on harvest, grazing and annual forage conservation, with forage maize being the most important silage crop (Alarcón, 1995). Even though forage maize is extensively bred in Europe, USA and Asia since the 1900’s, this started in Mexico only in the 1960’s, and little is known about genetic diversity in both agronomic and nutritive value traits. Our breeding program goals are to analyze combining ability of biomass and quality predictors and to study the genetic relationship of inbred lines between lowland tropical and temperate races from Mesa Central, by genetic and molecular approaches

Genetic and Molecular Characterization of Temperate and Tropical Forage Maize Inbred Lines

The livestock feeding in the Central highland of Mexico is based on harvest, grazing and annual forage conservation, being forage maize the most important silage crop (Alarcón, 1995). Even though forage maize is extensively bred in Europe, USA and Asia since 1900\u27s, this started in Mexico in the 1960\u27s, and little is known about the genetic diversity in both agronomic and nutritive value traits. Our breeding program goals are to analyze combining ability of biomass and quality predictors and to study the genetic relationship of inbred lines between lowland tropical and temperate races from Mesa Central, by genetic and molecular approaches

Efecto de Pseudomonas syringae subsp. syringae en el rendimiento y distribución de biomasa en trigo

The effect of Pseudomonas syringae subsp. syringae on seed yield, aerial biomass production and partitioning in wheat (Triticum aestivum L.) is unknown. A field experiment was carried out in two locations of the Mexican Highlands (Montecillo and Chapingo) to evaluate the response of two wheat cultivars (‘Seri M82’ and ‘Rebeca F2000’) to four inoculum rates (106, 8, 10 cfu mL–1, plus a control without inoculum). Disease incidence and severity, seed yield, seed number and seed size were measured. At flowering and seed physiological maturity, aerial biomass production and distribution of main stem, secondary stems and total plant were recorded. Source-sink relationships during the grain filling period were estimated. Higher values of disease incidence and severity were observed at Chapingo; the same traits were also greater in ‘Seri’ than in ‘Rebeca’ at both sites (p < 0.05). Seed yield, seed number and seed size of ‘Rebeca’ were higher (p < 0.05) than that of ‘Seri’. The pathogen reduced (p < 0.05) plant height, seed yield, seed yield components, and biomass production of most organs of main and secondary stems. The magnitude of the reductions was similar in both cultivars at both sites. The effect of the bacteria at each location was higher (p < 0.05) at greater doses affecting seed number more than seed weight. Stems prevailed as sink organs, while laminae, sheaths, spikes, and other vegetative parts predominated as source organs. Plant disease records should complement crop physiological variables to evaluate and to explain bacterial disease effectsEl efecto de Pseudomonas syringae subsp. syringae en el rendimiento de semilla y en la producción y distribución de biomasa aérea en trigo (Triticum aestivum L.) es desconocido. Se sembró un experimento en dos localidades de los Valles Centrales de México (Montecillo y Chapingo) para evaluar la respuesta de dos cultivares de trigo (‘Seri M82’ y ‘Rebeca F2000’) a cuatro dosis de inóculo (106, 8, 10 cfu mL–1, más un testigo sin inóculo). Se registraron datos de incidencia y severidad, rendimiento de semilla y número y tamaño de semilla. En la floración y madurez fisiológica de semilla, se registró la producción y distribución de biomasa aérea de tallos, vainas, limbos y espigas de tallos principales, secundarios y total por planta. Se estimaron las relaciones fuente-demanda durante el periodo de llenado de grano. La incidencia y severidad de la enfermedad fueron mayores en Chapingo, y en ‘Seri’ respecto a ‘Rebeca’ en ambas localidades (p < 0,05). El rendimiento de semilla, así como el número y tamaño, fue mayor (p < 0,05) en ‘Rebeca’ que en ‘Seri’. El patógeno redujo (p < 0,05) la altura de la planta, el rendimiento y sus componentes, y la producción de biomasa de la mayoría de los órganos de los tallos principales y secundarios; sin embargo, la magnitud de las reducciones fue similar en ambos cultivares. El efecto de la bacteria en cada localidad fue mayor (p < 0,05) a dosis mayores al afectar al número de semillas más que al peso de las mismas. Los tallos prevalecieron como órganos de demanda, mientras que limbos, vainas, espigas, y otras partes vegetativas predominaron como órganos fuente. Los reportes de enfermedades de las plantas podrían complementarse con variables fisiológicas del cultivo para evaluar y explicar los efectos de las enfermedades bacteriana

Distinción de especies del género Persea mediante RAPD e ISSR de ADN

With the aim of establishing a basis to differentiate part of the Persea genetic diversity, specially of the subgenus Persea maintained in the National Avocado Germplasm Repository of Mexico, eight species were studied (P. americana, P. steyermarkii, P. schiedeana, P. lingue, P. nubigena, P. floccosa, P. cinerascens y P. indica) with molecular markers by means of RAPD and ISSR techniques, where the PCR products were separated in acrylamide gels. The DNA fingerprinting was analyzed with multivariate statistical methods and bootstrapping to establish their genomic relationships. Useful DNA polymorphic fragments were found for the inter and intra-specific distinction of the eight species of Persea considered in the study. The statistical analysis of the DNA fingerprints by means of RAPD grouped the different species congruently with the actual taxonomic classification, compared with ISSR. According to the present study, P. indica y P. lingue show less genomic relationship with the rest of the species studied, and this is accordance to the fact that they correspond to the subgenus Eriodaphne. The results permitted to differentiate genotypes of the different species of the subgenus Persea that includes P. americana and an inter-specific hybrid included in the study.Con la finalidad de establecer bases para diferenciar parte de la diversidad genética de Persea y en especial del subgénero Persea resguardado en la colección nacional de germoplasma de aguacate de México, se estudiaron ocho especies (P. americana, P. steyermarkii, P. schiedeana, P. lingue, P. nubigena, P. floccosa, P. cinerascens y P. indica) con marcadores moleculares mediante las técnicas de RAPD e ISSR, donde los productos de PCR fueron separados en geles de acrilamida. Las huellas de ADN se analizaron con métodos estadísticos multivariadas y de remuestreo para conocer su relación genómica. Se detectaron fragmentos polimorfismos de ADN útiles para la distinción inter e intraespecífica de las ocho especies del género Persea en estudio. Los análisis estadísticos de las huellas de ADN mediante RAPD a diferencia de ISSR, agruparon de forma congruente a las diferentes especies de acuerdo a la taxonomía actual. De acuerdo al presente estudio, P. indica y P. lingue mantienen poca relación genómica con el resto de las especies estudiadas por pertenecen al subgénero Eriodaphne. Por otra parte los resultados permitieron diferenciar genotipos de las diferentes especies del subgénero Persea incluyendo a P. americana y un híbrido interespecífico incluido en el estudio

Variación de la región ribosómica nuclear en Crataegus L. del centro y sur de México

This study was conducted at the Universidad Autónoma de Chapingo and concluded in October 2008, to determine the genetic relationships among species of Crataegus fromcentral and southern Mexico. The variation in the sequences of the nuclear ribosomal region was low in all accessions of germplasm of Mexican Crataegus, and the phylogramonly showed separation of the species used as positive controls, but did not show a clear separation of groups of species. However, all accessions had the same pattern of nucleotide substitution and very low values of the distanceof nucleotide composition; thus, Mexican Crataegus species have high genetic relationship among them, but there is alack of evidence to conclude that they are variants of the same taxonomic species. C. nelsoni and C. stipulosa could be a source of genes for C. mexicana because both species,from Chiapas, have the closest relationship with this species,which has the best agronomic characteristics.Este estudio fuerealizado en la Universidad Autónoma Chapingo y concluido en octubre de 2008 y tuvo como objetivo determinar las relaciones genéticas entre especies de Crataegus del centro y sur de México. La variación en las secuencias de la región ribosómica nuclear fue baja en todas las accesiones de germoplasma de Crataegus mexicanos, y el filograma sólomostró separación de las especies usadas como controles positivos, pero no mostró una clara separación de gruposde especies. Sin embargo, todas las accesiones tuvieron un mismo patrón de sustitución de nucleótidos y muy bajos valores en la distancia de composición de nucleótidos; porlo que las especie s mexicanas de Crataegus mostraron altarelación genética, pero falta evidencia para concluir que son variantes de una misma especie taxonómica. C nelsoni y C.stipulosa pueden ser una fuente de genes para C. mexicana porque ambas especies, originarias de Chiapas, tienen la másestrecha relación con esta especie , que es la que presenta las mejores características agronómicas

Effect of pseudomonas syringae subsp. syringae on yield and biomass distribution in wheat [Efecto de pseudomonas syringae subsp. syringae en el rendimiento y distribuci�n de biomasa en trigo]

The effect of Pseudomonas syringae subsp. syringae on seed yield, aerial biomass production and partitioning in wheat (Triticum aestivum L.) is unknown. A field experiment was carried out in two locations of the Mexican Highlands (Montecillo and Chapingo) to evaluate the response of two wheat cultivars ('Seri M82' and 'Rebeca F2000') to four inoculum rates (106,8,10 cfu mL-1, plus a control without inoculum). Disease incidence and severity, seed yield, seed number and seed size were measured. At flowering and seed physiological maturity, aerial biomass production and distribution of main stem, secondary stems and total plant were recorded. Source-sink relationships during the grain filling period were estimated. Higher values of disease incidence and severity were observed at Chapingo; the same traits were also greater in 'Seri' than in 'Rebeca' at both sites (p < 0.05). Seed yield, seed number and seed size of 'Rebeca' were higher (p < 0.05) than that of 'Seri'. The pathogen reduced (p < 0.05) plant height, seed yield, seed yield components, and biomass production of most organs of main and secondary stems. The magnitude of the reductions was similar in both cultivars at both sites. The effect of the bacteria at each location was higher (p < 0.05) at greater doses affecting seed number more than seed weight. Stems prevailed as sink organs, while laminae, sheaths, spikes, and other vegetative parts predominated as source organs. Plant disease records should complement crop physiological variables to evaluate and to explain bacterial disease effects