Estudio del efecto de la sequía inducida por polietilenglicol en Capsicum frutescens en un sistema hidropónico

La sequía es el factor más común que limita el desarrollo y productividad de los cultivos, afectando severamente a la agricultura. En México, uno de los cultivos de importancia económica y gastronómica sensible al estrés hídrico es el género Capsicum. En el presente estudio se evaluó la aplicación de prolina en plantas de Capsicum frutescens expuestas a sequía inducida por polietilenglicol (PEG) en un sistema hidropónico. Empleando un diseño factorial 22, se evaluaron un total de 60 plántulas durante 120 h dividas en cuatro tratamientos: PEG (0 y 10 %) y Pro (0 y 10 mM) como variables de estudio. Los resultados demostraron que la exposición a 10 mM de Pro indujo un aumento significativo en la concentración de clorofila y de prolina endógena (hoja y raíz) en las plántulas en ausencia de estrés. Además, se observó un 80 % de supervivencia de las plántulas y un aumento en el contenido de prolina en aquellas que estuvieron expuestas a 10 mM Pro + 10 % PEG. De igual manera, se presentó un aumento en el contenido de clorofila (13 µg • mL-1), contenido relativo de agua (CRA) en raíz (77.6 %), porcentaje de electrolitos en hoja y raíz (~44 y ~52 % respectivamente), en comparación con el tratamiento de 0 mM Pro + 10 % PEG. Los resultados sugieren que la aplicación previa de prolina tiene un efecto positivo en la supervivencia de las plántulas bajo condiciones de sequía inducida por PEG

Molecular characterization and phylogenetic analysis of a Squash leaf curl virus isolate from Baja California Sur, Mexico

Background The begomovirus, squash leaf curl virus (SLCuV) is one of the causal agents of squash leaf curl (SLC) disease, which is among the most destructive diseases of cucurbit crops in tropical, subtropical, and semiarid regions worldwide. This disease was originally reported in the American continent with subsequent spread to the Mediterranean basin. Up to now, SLCuV has only been detected by PCR in Mexico. This study provides the first complete sequence of a Mexican SLCuV isolate from Baja California Sur (BCS). In addition, the genome of the virus was characterized, establishing its phylogenetic relationship with other SLCuV isolates. Methods The full genome (DNA-A and DNA-B) was amplified by rolling circle amplification, cloned and sequenced and the open reading frames (ORF) were annotated. Virus identification was performed according to the International Committee on Taxonomy of Viruses (ICTV) criteria for begomovirus species demarcation. To infer evolutionary relationship with other SLCuV isolates, phylogenetic and recombination analyses were performed. Results The SLCuV-[MX-BCS-La Paz-16] genome (DNA-A and DNA-B) had 99% identity with SLCuV reference genomes. The phylogenetic analysis showed that SLCuV-[MX-BCS-La Paz-16] is closely related to SLCuV isolates from the Middle East (Egypt, Israel, Palestine and Lebanon). No evidence of interspecific recombination was determined and iterons were 100% identical in all isolates in the SLCuV clade. Conclusions SLCuV-[MX-BCS-La Paz-16] showed low genetic variability in its genome, which could be due to a local adaptation process (isolate environment), suggesting that SLCuV isolates from the Middle East could have derived from the southwestern United States of America (USA) and northwestern Mexico

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

Effects of Vermicompost Leachate versus Inorganic Fertilizer on Morphology and Microbial Traits in the Early Development Growth Stage in Mint (Mentha spicata L.) And Rosemary (Rosmarinus officinalis L.) Plants under Closed Hydroponic System

The objective of this study was to compare the morphology of M. spicata and R. officinalis plants, and the relative abundance quantification, colony-forming units, ribotypes, and biofilm former bacteria under an inorganic fertilizer and the use of vermicompost leachate in the rhizosphere under a closed hydroponic system. In mint (Mentha spicata) plants treated with the vermicompost leachate, growth increase was determined mainly in root length from an average of 38 cm in plants under inorganic fertilizer to 74 cm under vermicompost leachate. In rosemary (Rosmarinus officinalis), no changes were determined between the two treatments. There were differences in the compositions of microbial communities: For R. officinalis, eight ribotypes were identified, seven for inorganic fertilizer and four for vermicompost leachate. For M. spicata, eight ribotypes were identified, three of them exclusive to vermicompost leachate. However, no changes were observed in microbial communities between the two treatments. Otherwise, some changes were observed in the compositions of these communities over time. In both cases, the main found phylum was Firmicutes, with 60% for R. officinalis and 80% for M. spicata represented by the Bacillus genus. In conclusion, the use of vermicompost leachate under the hydroponic system is a viable alternative to achieve an increase in the production of M. spicata, and for both plants (mint and rosemary), the quality of the product and the microbial communities that inhabited them remained unaltered

NB-LRR signaling induces translational repression of viral transcripts and the formation of RNA processing bodies through mechanisms differing from those activated by UV stress and RNAi

Plant NB-LRR proteins confer resistance to multiple pathogens, including viruses. Although the recognition of viruses by NB-LRR proteins is highly specific, previous studies have suggested that NB-LRR activation results in a response that targets all viruses in the infected cell. Using an inducible system to activate NB-LRR defenses, we find that NB-LRR signaling does not result in the degradation of viral transcripts, but rather prevents them from associating with ribo- somes and translating their genetic material. This indicates that defense against viruses involves the repression of viral RNA translation. This repression is specific to viral transcripts and does not involve a global shutdown of host cell trans- lation. As a consequence of the repression of viral RNA translation, NB-LRR responses induce a dramatic increase in the biogenesis of RNA processing bodies (PBs). We demonstrate that other pathways that induce translational repression, such as UV irradiation and RNAi, also induce PBs. However, by investigating the phosphorylation status of eIF2$ and by using suppressors of RNAi we show that the mechanisms leading to PB induction by NB-LRR signaling are different fro