Physiological and genetic analysis of a mapping population responsiveness to plant growth-promoting Azospirillum in wheat

Azospirillum brasilense is a plant growth-promoting rhizobacteria (PGPR) with the potential of being employed as an inoculant to decrease the use of chemical fertilizers. We investigated the effect of A. brasilense inoculation on a doubled haploid population derived from Opata / WSHD67.2(257) cross and detected Quantitative Trait Loci (QTL) for seven agronomic traits. The population was segregated, concerning their response to inoculation, into three subgroups: neutral, positive, and negative in a proportion of 60:25:15. A total of 18 major QTL and 83 minor QTL controlled the expression of measured traits. Nineteen QTL showed pleiotropic characteristics; chromosomes 5A, 7A, 7B, and 7D were distinguished as those with QTL controlling four of the seven phenotypes measured. The sequences of nearest markers to major QTL detected synteny to rice sequences that codified for at least 38 candidate genes described and discussed as a first step to understanding the interaction of wheat with A. brasilense

Honduras 2013 : proceso electoral, financiamiento y transparencia. Informe de monitoreo

El proceso electoral que concluyó con la celebración de las elecciones generales el domingo 24 de noviembre del año 2013, fue un proceso especial y de gran significado en la historia de la transición política hacia la democracia en la sociedad hondureña. A lo largo de esta transición, a veces tan errática y difícil como incierta y prolongada, los hondureños hemos ido a las urnas en una decena de veces para escoger a nuestros gobernantes. Pero nunca antes el torneo electoral había sido tan abierto y plural, así como tan reñido y polarizado ideológicamente, como lo ha sido en esta ocasión. Marcadas por la impronta del reciente golpe de Estado perpetrado el 28 de junio del año 2009, las elecciones de 2013 se llevaron a cabo en medio de un clima de mucha expectación ciudadana y grandes posibilidades de llevar a cabo cambios políticos importantes en la vida de la nación. Nunca antes el status quo había sido tan cuestionado y puesto en duda como en el proceso electoral del año 2013

Design and application of new 16S rRNA-targeted oligonucleotide probes for the Azospirillum-Skermanella-Rhodocista-cluster

The genera Azospirillum, Skermanella and Rhodocista form a phylogenetic subgroup within the alfa subclass of Proteobacteria. Based on comparative 16S rRNA sequence analysis a nested set of new oligonucleotide probes was designed. It comprises probes for the whole genus cluster Azospirillum-Skermanella-Rhodocista, for the Azospirilli subcluster I including A. lipoferum, A. doebereinerae, A. largimobile, A. brasilense and A. halopraeferens, for the Azospirilli subcluster II including A. amazonense, A. irakense and the genus Skermanella, for the genus Rhodocista as well as for all Azospirilli species or species cluster. The new probes allow a fast and reliable in situ identification of bacteria belonging to the Azospirillum-Skermanella-Rhodocista-cluster at different phylogenetic levels. The specificity of the new probes was tested with 56 strains of the Azospirillum-Rhodocista-Skermanella-cluster and selected reference cells from other genera by hybridising with the complete probe set. In addition, applications of the fluorescently labelled probes for in situ identification of isolates and for the in situ localisation of A. brasilense on maize roots were demonstrated using confocal laser scanning microscopy. Key words: Azospirillum – Rhodocista – Skermanella – fluorescence in situ hybridization – FISH – 16S rRNA – top to bottom approach – identification – monitorin

Growth effects in oregano plants (Origanum vulgare L.) assessment through inoculation of bacteria isolated from crop fields located on desert soils.

The bacteria can establish beneficial interactions with plants acting as growth promoters and enhance stress tolerance during plant interactions. Likewise, bacteria are able to develop multi-species communities where multiple interactions are possible. In this work, we assessed the physiological effects of three bacteria isolated from an arid environment (Bacillus niacini, B. megaterium, and Moraxella osloensis) applied as single-species or as a consortium, on oregano (Origanum vulgare L.) plants. Moreover, we assessed the quorum-sensing (QS) signaling activity to determine the molecular communication between plant growth-promoting (PGP) bacteria. The plant inoculation with B. megaterium showed a positive effect on morphometric and physiologic parameters. However, no synergistic effects were determined when bacterial consortium were inoculated. Likewise, the QS signaling activation in biofilm assays was determined only for inter-species interaction inside the Bacillus genus, but not activation with either interaction with M. osloensis. These results suggest a neutral or antagonistic interaction for inter-specific bacterial biofilm establishment, as well as for the interaction with oregano plants when bacteria were inoculated in a consortium. In conclusion, we were able to determine that the bacterial interactions are not always positive or synergistic, but also might be neutral or antagonistic.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Bacterial communities of the psyllid pest Bactericera cockerelli (Hemiptera: Triozidae) Central haplotype of tomato crops cultivated at different locations of Mexico

Background The psyllid, Bactericera cockerelli, is an insect vector of ‘Candidatus Liberibacter’ causing “Zebra chip” disease that affects potato and other Solanaceae crops worldwide. In the present study, we analyzed the bacterial communities associated with the insect vector Bactericera cockerelli central haplotype of tomato crop fields in four regions from Mexico. Methods PCR was used to amplify the mitochondrial cytochrome oxidase I gene (mtCOI) and then analyze the single nucleotide polymorphisms (SNP) and phylogenetic analysis for haplotype identification of the isolated B. cockerelli. Moreover, we carried out the microbial diversity analysis of several B. cockerelli collected from four regions of Mexico through the NGS sequencing of 16S rRNA V3 region. Finally, Wolbachia was detected by the wsp gene PCR amplification, which is the B. cockerelli facultative symbiont. Also we were able to confirm the relationship with several Wolbachia strains by phylogenetic analysis. Results Our results pointed that B. cockerelli collected in the four locations from Mexico (Central Mexico: Queretaro, and Northern Mexico: Sinaloa, Coahuila, and Nuevo Leon) were identified, such as the central haplotype. Analyses of the parameters of the composition, relative abundance, and diversity (Shannon index: 1.328 ± 0.472; Simpson index 0.582 ± 0.167), showing a notably relatively few microbial species in B. cockerelli. Analyses identified various facultative symbionts, particularly the Wolbachia (Rickettsiales: Anaplasmataceae) with a relative abundance higher. In contrast, the genera of Sodalis and ‘Candidatus Carsonella’ (Gammaproteobacteria: Oceanospirillales: Halomonadaceae) were identified with a relatively low abundance. On the other hand, the relative abundance for the genus ‘Candidatus Liberibacter’ was higher only for some of the locations analyzed. PCR amplification of a fragment of the gene encoding a surface protein (wsp) of Wolbachia and phylogenetic analysis corroborated the presence of this bacterium in the central haplotype. Beta-diversity analysis revealed that the presence of the genus ‘Candidatus Liberibacter’ influences the microbiota structure of this psyllid species. Conclusions Our data support that the members with the highest representation in microbial community of B. cockerelli central haplotype, comprise their obligate symbiont, Carsonella, and facultative symbionts. We also found evidence that among the factors analyzed, the presence of the plant pathogen affects the structure and composition of the bacterial community associated with B. cockerelli

Changes of Soil Bacterial Diversity as a Consequence of Agricultural Land Use in a Semi-Arid Ecosystem

<div><p>Natural scrublands in semi-arid deserts are increasingly being converted into fields. This results in losses of characteristic flora and fauna, and may also affect microbial diversity. In the present study, the long-term effect (50 years) of such a transition on soil bacterial communities was explored at two sites typical of semi-arid deserts. Comparisons were made between soil samples from alfalfa fields and the adjacent scrublands by two complementary methods based on 16S rRNA gene fragments amplified from total community DNA. Denaturing gradient gel electrophoresis (DGGE) analyses revealed significant effects of the transition on community composition of <i>Bacteria</i>, <i>Actinobacteria</i>, <i>Alpha</i>- and <i>Betaproteobacteria</i> at both sites. PhyloChip hybridization analysis uncovered that the transition negatively affected taxa such as <i>Acidobacteria</i>, <i>Chloroflexi</i>, <i>Acidimicrobiales</i>, <i>Rubrobacterales</i>, <i>Deltaproteobacteria</i> and <i>Clostridia</i>, while <i>Alpha-, Beta- and Gammaproteobacteria, Bacteroidetes</i> and <i>Actinobacteria</i> increased in abundance. Redundancy analysis suggested that the community composition of phyla responding to agricultural use (except for <i>Spirochaetes</i>) correlated with soil parameters that were significantly different between the agricultural and scrubland soil. The arable soils were lower in organic matter and phosphate concentration, and higher in salinity. The variation in the bacterial community composition was higher in soils from scrubland than from agriculture, as revealed by DGGE and PhyloChip analyses, suggesting reduced beta diversity due to agricultural practices. The long-term use for agriculture resulted in profound changes in the bacterial community and physicochemical characteristics of former scrublands, which may irreversibly affect the natural soil ecosystem.</p> </div

Boxplots of the variation of community structure under same sites and land use based on DGGE profiles for a: <i>Bacteria</i>; b: <i>Actinobacteria</i>; c: <i>Alphaproteobacteria</i>; d: <i>Betaproteobacteria</i>.

<p>Boxplots of the variation of community structure under same sites and land use based on DGGE profiles for a: <i>Bacteria</i>; b: <i>Actinobacteria</i>; c: <i>Alphaproteobacteria</i>; d: <i>Betaproteobacteria</i>.</p

Percent dissimilarity of microbial DGGE fingerprints of different taxa for soils compared between alfalfa and scrubland or between site 1 and site 2.

*<p>Significant (p<0.05) difference in community fingerprints between treatments as revealed by permutation tests.</p

Honduras 2013 : proceso electoral, financiamiento y transparencia. Informe de monitoreo

El proceso electoral que concluyó con la celebración de las elecciones generales el domingo 24 de noviembre del an&#771;o 2013, fue un proceso especial y de gran significado en la historia de la transición política hacia la democracia en la sociedad honduren&#771;a. A lo largo de esta transición, a veces tan errática y difícil como incierta y prolongada, los honduren&#771;os hemos ido a las urnas en una decena de veces para escoger a nuestros gobernantes. Pero nunca antes el torneo electoral había sido tan abierto y plural, así como tan ren&#771;ido y polarizado ideológicamente, como lo ha sido en esta ocasión. Marcadas por la impronta del reciente golpe de Estado perpetrado el 28 de junio del an&#771;o 2009, las elecciones de 2013 se llevaron a cabo en medio de un clima de mucha expectación ciudadana y grandes posibilidades de llevar a cabo cambios políticos importantes en la vida de la nación. Nunca antes el status quo había sido tan cuestionado y puesto en duda como en el proceso electoral del an&#771;o 2013