Zebra chip spatial behavior and Bactericera cockerelli (Sulc) (Hemiptera: Triozidae) in Solanum tuberosum L. in valleys high of Mexico.

Comportamiento espacial de Zebra chip y Bactericera cockerelli, en cultivo de papa.En México la producción de papa es afectada por la enfermedad de Zebra chip causada por la bacteria Candidatus Liberibacter solanacearum que es transmitida por el psílido Bactericera cockerelli. El objetivo de esta investigación fue determinar el comportamiento espacial de Zebra chip y Bactericera cockerelli mediante técnicas geoestadísticas y la detección de la bacteria aplicando técnicas moleculares. En el año 2013 se seleccionó dos parcelas comerciales de papa de la variedad Fianna; un total de 121 puntos fueron muestreados cada 10 m con el método de cuadrícula por parcela, georreferenciando cada planta. La incidencia de la enfermedad se determinó en campo sobre la base de los síntomas observados; la detección molecular de la bacteria se realizó con los iniciadores Lp Frag 1-25F/427R. La incidencia de la enfermedad en la parcela 1 fue de 30% y de 25% en la parcela 2; la bacteria se detectó en el 27% de las plantas sintomáticas y en el 14% de las asintomáticas. La distribución espacial de la enfermedad, el patógeno y el vector se presentó en forma agregada, ajustándose a los modelos gaussiano y esférico; en la parcela 2, los centros de agregación del estadio adulto y la bacteria presentaron la misma ubicación.Universidad Autónoma del Estado de México CONACY

Zebra chip spatial behavior and Bactericera cockerelli (Sulc) (Hemiptera: Triozidae) in Solanum tuberosum L. in valleys high of Mexico

En México la producción de papa es afectada por la enfermedad de Zebra chip causada por la bacteria Candidatus Liberibacter solanacearum que es transmitida por el psílido Bactericera cockerelli. El objetivo de esta investigación fue determinar el comportamiento espacial de Zebra chip y Bactericera cockerelli mediante técnicas geoestadísticas y la detección de la bacteria aplicando técnicas moleculares. En el año 2013 se seleccionó dos parcelas comerciales de papa de la variedad Fianna; un total de 121 puntos fueron muestreados cada 10 m con el método de cuadrícula por parcela, georreferenciando cada planta. La incidencia de la enfermedad se determinó en campo sobre la base de los síntomas observados; la detección molecular de la bacteria se realizó con los iniciadores Lp Frag 1-25F/427R. La incidencia de la enfermedad en la parcela 1 fue de 30% y de 25% en la parcela 2; la bacteria se detectó en el 27% de las plantas sintomáticas y en el 14% de las asintomáticas. La distribución espacial de la enfermedad, el patógeno y el vector se presentó en forma agregada, ajustándose a los modelos gaussiano y esférico; en la parcela 2, los centros de agregación del estadio adulto y la bacteria presentaron la misma ubicación.In Mexico potato production is affected by the disease Zebra chip; which it caused by the bacterium Candidatus Liberibacter solanacearum and is vectored by the psyllid Bactericera cockerelli. The objective of this research was to determine the spatial behavior of Zebra chip and Bactericera cockerelli with geostatistical techniques and bacterium detection using molecular techniques. In 2013 two commercial plots were selected cultivated with the variety Fianna; a total of 121 points were sampled every 10 m using the method of grid, in wich each plant was georeferenced. The incidence of the disease was determined by the symptoms observed in the field; the molecular detection of bacterium was performed using Lp 1-25F Frag/427R primers. The disease incidence in plot 1 was 30% and 25% in plot 2; the bacterium was detected in 27% of plants where symptoms were presented and in 14% of asymptomatic ones. The spatial distribution of the disease, the pathogen and the vector was presented in an aggregated form, adjusting the gaussian and spherical model. In parcel 2, the aggregation centers of the adult stage and the bacterium showed the same location.Fil: Contreras-Rendón, Alejandra. Universidad Autónoma del Estado de México. Facultad de Ciencias AgrícolasFil: Gutiérrez-Ibáñez, Ana Tarin. Universidad Autónoma del Estado de México. Facultad de Ciencias AgrícolasFil: Sánchez-Pale, Jesús Ricardo. Universidad Autónoma del Estado de México. Facultad de Ciencias AgrícolasFil: Silva-Rojas, Hilda Victoria. Colegio de Postgraduados. Campus Montecillo (México)Fil: Laguna-Cerda, Antonio. Universidad Autónoma del Estado de México. Facultad de Ciencias Agrícola

Spatial pattern of mottled stripe disease (Herbaspirillum rubrisubalbicans) in sugar cane

Sugar cane (Saccharum spp. hybrids) is the most important agroindustrial crop of the tropics. Recently, sugar cane plants with chlorotic leaf streaking associated with the bacterium Herbaspirillum rubrisubalbicans have been observed. This disease impacts photosynthetic capacity and yield. Characterizing the spatio-temporal behavior of chlorotic mottling using prediction maps is an important element of integrated disease management. Here, we determine the spatial distribution of mottled stripe disease in sugar cane in southeastern Mexico. To do this, we randomly chose and georeferenced 80 points in commercial plots in 2016 and 2017 to determine the disease incidence. We generated an experimental semivariogram based on a predetermined theoretical model and estimated Kriging. The incidence was 2.93% in 2016 and 5.36% in 2017 in varieties ICP-MEX-92-1420, CP-72-2086, ITV-92-373, MEX-79434 and MEX-69-290. The spatial behavior of the bacteria fit the pentaspherical model in 2016 and the spherical model in 2017. Spatial interpolation was validated by Mean Error (ME), Root Mean Square Error (RMSE) and Mean Standardized Prediction Error (MSPE) values near zero, visualized using the generated map. The results will be used to guide management of mottled stripe disease in sugar cane in the affected area. Highlights H. rubrisubalbicans can persist from sugar cane growing season to the next and spread from one plot to another by different mechanisms. The chlorotic mottling of sugar cane showed an aggregate type spatial behavior at the regional level. The differences in spatial patterns between seasons show the dispersion potential of the disease in this crop system, as well as a latent infestation in the area. The semivariograms and maps show aggregate behavior of this disease, expressed as different spatial patterns given by the spatial dependence among points and the severity of the effects in each plot.Sugar cane (Saccharum spp. hybrids) is the most important agroindustrial crop of the tropics. Recently, sugar cane plants with chlorotic leaf streaking associated with the bacterium Herbaspirillum rubrisubalbicans have been observed. This disease impacts photosynthetic capacity and yield. Characterizing the spatio-temporal behavior of chlorotic mottling using prediction maps is an important element of integrated disease management. Here, we determine the spatial distribution of mottled stripe disease in sugar cane in southeastern Mexico. To do this, we randomly chose and georeferenced 80 points in commercial plots in 2016 and 2017 to determine the disease incidence. We generated an experimental semivariogram based on a predetermined theoretical model and estimated Kriging. The incidence was 2.93% in 2016 and 5.36% in 2017 in varieties ICP-MEX-92-1420, CP-72-2086, ITV-92-373, MEX-79434 and MEX-69-290. The spatial behavior of the bacteria fit the pentaspherical model in 2016 and the spherical model in 2017. Spatial interpolation was validated by Mean Error (ME), Root Mean Square Error (RMSE) and Mean Standardized Prediction Error (MSPE) values near zero, visualized using the generated map. The results will be used to guide management of mottled stripe disease in sugar cane in the affected area. Highlights H. rubrisubalbicans can persist from sugar cane growing season to the next and spread from one plot to another by different mechanisms. The chlorotic mottling of sugar cane showed an aggregate type spatial behavior at the regional level. The differences in spatial patterns between seasons show the dispersion potential of the disease in this crop system, as well as a latent infestation in the area. The semivariograms and maps show aggregate behavior of this disease, expressed as different spatial patterns given by the spatial dependence among points and the severity of the effects in each plot

Pantoea agglomerans in Immunodeficient Patients with Different Respiratory Symptoms

The aim of this paper was to determine in 32 patients from 4 different Mexican hospitals the frequency of opportunistic bacteria in the 2010 to 2011 time period. The patients were divided in 4 groups. Group 1 included 21 HIV positive patients with acute respiratory syndrome. Four HIV positive patients with tuberculosis symptoms were included in Group 2; two patients with tuberculosis symptoms and one asymptomatic person formed Group 3. Reference Group 4 included 4 patients from whom 4 strains of Mycobacterium spp. had been reported. The strains were isolated and identified by 16S rRNA gene amplification, API 20E and 50CH, biochemical test, and antibiotic sensitivity. The strains found were 10 Pantoea agglomerans, 6 Mycobacterium spp., 6 Pseudomonas spp. and 10 strains of normal floral species: Thermoactinomycetes bacterium (1), Enterococcus faecium (2), Bacillus licheniformis (1), Lactobacillus rhamnosus (2), Streptococcus oralis (2), Streptococcus anginosus (1), and Enterobacter hormaechei (1)

Caracterización molecular de variedades de caña de azúcar cultivadas en el estado de Tabasco, México

To characterize varieties in recent years have used different types of morphological, biochemical and molecular methods. The aim of this study was to characterize molecular genetic variability in varieties of sugarcane (Saccharum spp.) grown in the state of Tabasco, Mexico, by AFLP. It was used 12 varieties of sugarcane. Young leaves of plants growing in the field were selected for experiment. After making 12 combinations of primers, the results indicated that the combination E-ACC/M-CTA produced 72 to 1353 bp polymorphic fragments. The dendrogram revealed two distinct groups of Saccharum spp. and a variety that differed from both. Group I comprised the varieties C 87-51, 96-40 ATM, B 4362, 69-290 Mex, Mex Mex 91-130 and 57-1285, which formed a cluster and showed a similarity of 0.77%. Group II included the varieties RD 75-11, Mex 79-431, SP 70-1284, 72-2086 and CP Mex 59-32 which formed another cluster with 0.70%. The variety Mex 68-P-23 differed from the other 11 varieties.Keywords: DNA, AFLP, molecular markersEl objetivo del presente trabajo fue caracterizar molecularmente la variabilidad genética en variedades de caña de azúcar (Saccharum spp.) cultivadas en el estado de Tabasco, México, mediante AFLP. Se utilizaron 12 variedades de caña de azúcar de las cuales se tomaron hojas jóvenes de plantas en campo. Después de realizar 12 combinaciones de cebadores, los resultados indicaron que la combinación E-ACC/M-CTA produjo fragmentos polimórficos de 72 a 1353 pb. El dendrograma reveló dos grupos distintos de Saccharum spp. y una variedad que se diferenció de ambos. El grupo I comprendió las variedades C 87-51, ATM 96-40, B 4362, Mex 69-290, Mex 57-1285 y Mex 91-130, que formaron un conglomerado y presentaron una similitud del 0.77%. El grupo II comprendió las variedades RD 75-11, Mex 79-431, SP 70-1284, Mex 59-32 y CP 72-2086 las cuales conformaron otro conglomerado con 0.70%. La variedad Mex 68-P-23 se diferenció de las otras 11 variedades.Palabras clave: ADN, AFLP, marcadores moleculare

Isolation of Bacteria with Antifungal Activity against the Phytopathogenic Fungi Stenocarpella maydis and Stenocarpella macrospora

Stenocarpella maydis and Stenocarpella macrospora are the causal agents of ear rot in corn, which is one of the most destructive diseases in this crop worldwide. These fungi are important mycotoxin producers that cause different pathologies in farmed animals and represent an important risk for humans. In this work, 160 strains were isolated from soil of corn crops of which 10 showed antifungal activity against these phytopathogens, which, were identified as: Bacillus subtilis, Pseudomonas spp., Pseudomonas fluorescens, and Pantoea agglomerans by sequencing of 16S rRNA gene and the phylogenetic analysis. From cultures of each strain, extracellular filtrates were obtained and assayed to determine antifungal activity. The best filtrates were obtained in the stationary phase of B. subtilis cultures that were stable to the temperature and extreme pH values; in addition they did not show a cytotoxicity effect against brine shrimp and inhibited germination of conidia. The bacteria described in this work have the potential to be used in the control of white ear rot disease

Endophytic Trichoderma Species Isolated from Persea americana and Cinnamomum verum Roots Reduce Symptoms Caused by Phytophthora cinnamomi in Avocado

Avocado root rot caused by the oomycete Phytophthora cinnamomi is a severe disease that affects avocado production in Mexico and worldwide. The use of biological control agents such as Trichoderma species isolated from places where the disease is always present, represents an efficient alternative to reduce losses. Thus, the objective of this research was to evaluate the biocontrol ability of 10 endophytic Trichoderma spp. strains against P. cinnamomi tested both in vitro and in the greenhouse. The endophytic Trichoderma spp. were recovered from Persea americana and Cinnamomum verum roots, isolated and purified on potato–dextrose–agar medium. Ten strains were identified by phylogenetic reconstruction of the internal transcribed spacer region of rDNA sequences as T. asperellum (T-AS1, T-AS2, T-AS6, and T-AS7), T. harzianum (T-H3, T-H4, and T-H5), T. hamatum (T-A12), T. koningiopsis (T-K8 and T-K11), and P. cinnamomi (CPO-PCU). In vitro dual-culture assay, the percentage of inhibition of radial growth (PIRG) between Trichoderma spp. and P. cinnamomi strains was measured according to the Bell’s scale. PIRG results indicated that T-AS2 reached the highest value of 78.32%, and T-H5 reached the lowest value of 38.66%. In the greenhouse, the infection was evaluated according to the percentage of disease incidence. Plants with the lowest incidence of dead by avocado root rot were those whose seedlings were inoculated with T-AS2 and T-AS7, resulting in only 5% death by root rot caused by P. cinnamomi. The disease incidence of seedlings with wilt symptoms and death decreased more than 50% in the presence of Trichoderma spp. Relying on the results, we conclude that T. asperellum and T. harzianum contribute to the biocontrol of soil-borne pathogenic oomycete P. cinnamomi

La pigmentación de Fusarium verticilliodes (Sacc.) como factor de virulencia en plántulas de maíz

This researchaimed to determine the relationship between the color of thepigment produced by isolates of F. verticilliodes and virulencein maize seedlings. Symptomatic and asymptomatic corn cobswere collected in Veracruz State, Mexico during the springsummercycle of 2008. The experiment was analyzed using anexperimental design in split plots with a double division, undergreenhouse conditions during two crop cycles, fall-winter of2008 and spring-summer of 2009, in the Postgraduate CollegeCampus Montecillo, Mexico State. The pigmentation of theisolates obtained from symptomatic seeds with mycelium wasmore intense with a purple color, and the white myceliumisolates showed a more homogeneous color. Isolates fromasymptomatic seeds had a tenuous violet coloration, and fromwhite to cream coloration of mycelium. It was observed thatisolates from symptomatic and asymptomatic seeds werepathogenic; the purple isolations from symptomatic seedswere more virulent than the white isolate, opposite to whathappened with the isolation from asymptomatic seeds, inwhich the white mycelium was more virulent.El objetivode este trabajo fue determinar la relación entre el colordel pigmento producido por aislamientos de F. verticillioidesy la virulencia en plántulas de maíz. Las mazorcas de maízsintomáticas y asintomáticas se colectaron en el Estado deVeracruz, México durante el ciclo agrícola primavera-verano2008. El experimento se analizó siguiendo un diseño experimentalen parcelas con doble división y se realizó en condicionesde invernadero en dos ciclos; otoño- invierno 2008y primavera-verano 2009, en el Colegio de PostgraduadosCampus Montecillo, Estado de México. La pigmentaciónde los aislamientos obtenidos de semillas sintomáticas conmicelio morado, fue más intensa y con micelio blanco mostraronun color más homogéneo, mientras que los de semillasasintomáticas tuvieron coloraciones de micelio violeta tenuey de blanco a crema. Los aislamientos obtenidos de semillassintomáticas y asintomáticas fueron patogénicos, el de colormorado de semillas sintomáticas fue más virulento que elblanco, caso contrario en semillas asintomáticas, donde elblanco fue más virulento

Colletotrichum fructicola, a Member of Colletotrichum gloeosporioides sensu lato, is the Causal Agent of Anthracnose and Soft Rot in Avocado Fruits cv. “Hass”

The filamentous Ascomycota Colletotrichum gloeosporioides sensu lato is a fungus that has been reported worldwide as a causal agent of anthracnose disease in avocado and other crops. In Mexico, this species affects fruits from an early stage of development in the orchard until the post-harvest stage. Although fungicides are continuously applied to control Colletotrichum species, pericarp cankers and soft rot mesocarp in fruits are still frequently observed. Considering the lack of a precise description of the causative agent, the aim of the current study was to determine the pathogens involved in this symptomatology. Twenty-four isolates were consistently obtained from the pericarp of avocado fruits cv. “Hass” collected in the central avocado-producing area of Mexico. Morphological features such as colony growth, conidia size, and mycelial appressorium were assessed. Bayesian multilocus phylogenetic analyses were performed using amplified sequences of the internal transcribed spacer region of the nuclear ribosomal DNA; actin, chitin synthase, glyceraldehyde-3-phosphate dehydrogenase partial genes; and APn2-Mat1-2 intergenic spacer and mating type Mat1-2 partial gene from the nine selected isolates. In addition, fruits were inoculated with a conidial suspension and reproducible symptoms confirmed the presence of Colletotrichum fructicola in this area. This pathogenic species can now be added to those previously reported in the country, such as C. acutatum, C. boninense, C. godetiae, C. gloeosporioides, and C. karstii. Disease management programs to reduce the incidence of anthracnose should include C. fructicola to determine its response to fungicides that are routinely applied, considering that the appearance of new species is affecting the commercial quality of the fruits and shifting the original population structure