Sinorhizobium fredii HH103 RirA is required for oxidative stress resistance and efficient symbiosis with Soybean

Members of Rhizobiaceae contain a homologue of the iron-responsive regulatory protein RirA. In different bacteria, RirA acts as a repressor of iron uptake systems under iron-replete conditions and contributes to ameliorate cell damage during oxidative stress. In Rhizobium leguminosarum and Sinorhizobium meliloti, mutations in rirA do not impair symbiotic nitrogen fixation. In this study, a rirA mutant of broad host range S. fredii HH103 has been constructed (SVQ780) and its free-living and symbiotic phenotypes evaluated. No production of siderophores could be detected in either the wild-type or SVQ780. The rirA mutant exhibited a growth advantage under iron-deficient conditions and hypersensitivity to hydrogen peroxide in iron-rich medium. Transcription of rirA in HH103 is subject to autoregulation and inactivation of the gene upregulates fbpA, a gene putatively involved in iron transport. The S. fredii rirA mutant was able to nodulate soybean plants, but symbiotic nitrogen fixation was impaired. Nodules induced by the mutant were poorly infected compared to those induced by the wild-type. Genetic complementation reversed the mutant’s hypersensitivity to H2O2, expression of fbpA, and symbiotic deficiency in soybean plants. This is the first report that demonstrates a role for RirA in the Rhizobium-legume symbiosis.Andalucian Government Grant No. P11-CVI-7500Spanish Government Grant Nos. BIO2013-42801-P and BIO2016-78409-REuropean Regional Development Funds (ERDF)VPPI (V Plan Propio de Investigación) of University of Seville

Estudios de infección de spongospora subterránea en papa (solanum tuberosum) variedad comercial diacol capiro

Spongospora subterranea (Wallroth) Lagerheim f. sp. subterranea Tomlinson es el agente causal de la roña o sarna polvosa de la papa y, además, es vector del virus potato mop top (PMTV). Es un patógeno protozoario, que causa su infección por medio de zoosporas que se encuentran en quistosoros los cuales son el principal modo de dispersión de la enfermedad. Éstos pueden permanecer en el suelo, raíces y tubérculos como estructuras de resistencia por varios años hasta que las condiciones medio ambientales favorezcan la liberación de zoosporas y se dé una nueva infección en las plantas de papa. En el presente trabajo se evaluó un método de bioensayo con el fin de establecer, bajo condiciones controladas, la infección de Spongospora subterranea en la variedad comercial de papa Diacol Capiro. Para tal fin se realizó un experimento, en el cual se evaluaron los efectos de tres fuentes de inóculo: quistosoros provenientes de suelo, de raíz y de tubérculo, con el fin de determinar la fuente más infectiva y la que provocara el desarrollo de la enfermedad. Las plántulas fueron inoculadas con una solución infectiva con una concentración de 1.6x105 quistososros/ml en condiciones de invernadero. Las evaluaciones fueron realizadas a los 19, 34, 64 y 93 días luego de ser inoculadas. Siguiendo la metodología propuesta y realizado el análisis microscópico respectivo, sólo fue posible encontrar algunas estructuras relacionadas en una observación, lo cual no permite confirmar la presencia general del patógeno luego de la inoculación.   Abstract Spongospora subterranea (Wallroth) Lagerheim f. sp. subterranea Tomlinson causes powdery scab in potato and is also vector to the mop-top virus (PMTV) in potato. Is a plasmodiophorids; infections occur through zoospores which are inside resistance spores called sporeballs or cystosori which are the principal way of the disease dispersion. Sporeballs can remains on soil, roots and tubers as resistance structure, and can still there for many years until the weather conditions being favorable to zoospores release starting a new infections on potato plants. In this study was evaluated a bioassay method with the aim to establish an infection from to Diacol Capiro potato variety on greenhouse conditions. It was carried out an experiment which tried to evaluate three different inoculums sources: cystosori from soil, potato roots and tubers, in order to identify the most infectious source and the one which cause the development of the disease. The plants were inoculated, in greenhouse conditions, by a cystosori infected solutions with a 1.6x105 cystosori/ml concentration. The evaluations were made 19, 34, 64 and 93 days after inoculation. Following this methodology and after all the respective microscopical observations, it was not possible to found many clearly structure related to which does not allowed to confirm the presence of the pathogen after the inoculation.

Sinorhizobium fredii Strains HH103 and NGR234 Form Nitrogen Fixing Nodules With Diverse Wild Soybeans (Glycine soja) From Central China but Are Ineffective on Northern China Accessions

Sinorhizobium fredii indigenous populations are prevalent in provinces of Central China whereas Bradyrhizobium species (Bradyrhizobium japonicum, B. diazoefficiens, B. elkanii, and others) are more abundant in northern and southern provinces. The symbiotic properties of different soybean rhizobia have been investigated with 40 different wild soybean (Glycine soja) accessions from China, Japan, Russia, and South Korea. Bradyrhizobial strains nodulated all the wild soybeans tested, albeit efficiency of nitrogen fixation varied considerably among accessions. The symbiotic capacity of S. fredii HH103 with wild soybeans from Central China was clearly better than with the accessions found elsewhere. S. fredii NGR234, the rhizobial strain showing the broadest host range ever described, also formed nitrogen-fixing nodules with different G. soja accessions from Central China. To our knowledge, this is the first report describing an effective symbiosis between S. fredii NGR234 and G. soja. Mobilization of the S. fredii HH103 symbiotic plasmid to a NGR234 pSym-cured derivative (strain NGR234C) yielded transconjugants that formed ineffective nodules with G. max cv. Williams 82 and G. soja accession CH4. By contrast, transfer of the symbiotic plasmid pNGR234a to a pSym-cured derivative of S. fredii USDA193 generated transconjugants that effectively nodulated G. soja accession CH4 but failed to nodulate with G. max cv. Williams 82. These results indicate that intra-specific transference of the S. fredii symbiotic plasmids generates new strains with unpredictable symbiotic properties, probably due to the occurrence of new combinations of symbiotic signals.España, Junta de Andalucía P11-CVI-7500España Ministerio de Economía y Competitividad BIO2016-78409-

The Sinorhizobium fredii HH103 double-edged sword

Rhizobia are soil proteobacteria able to stablish an efficient symbiosis with legume plants (Poole et al., 2018). In this interaction, bacteria infect the plant roots and penetrate inside through the root hairs. Simultaneously to the infection process, plant develop new organs called nodules, generally located on roots, which hosted the rhizobial cells. Once rhizobia are located in the nodules, they invade the plant cells and differentiate into bacteroids, a morphological and physiological state able to fix the atmospheric nitrogen to ammonium, which is supplied to the plant (Tsyganova et al., 2017). This interaction requires a complex and coordinated molecular signals interchange between two partners, since this event determine the susceptible plants to be nodulate by a specific rhizobium and therefore the success of the process (Oldroyd 2013). One of these signals are the molecules called Nod Factors, lipochitooligosaccharides secreted by the bacteria in response to the plant signals and detected by the plant receptors. Several bacterial regulators finely regulate these molecules; however, their overproduction produces changes in the host specificity and the effectiveness of the infection process.Motivation: Since the host specificity is determined by the bacterial and plant signals, the alteration of some of them could modify the bacterial host range and even increase the efficiency with other plants.Methods: All the experiments were carried out with Sinorhizobium fredii HH103, a rhizobial strain isolated from China and natural symbiont of soybean (Glycine max cv. Williams).Gene expression analysis were carried out by RNA-seq and validated by RT-qPCR.Nod Factors were extracted from the supernatant culture and analysed by HPLC-HRMS/MS.Plant assays with Glycine max cv. Williams, Lotus burttii and L. japonicus Gifu were carried out in Leonard jars.Infection mode analyses were carried out by epifluorescence microscopy.Results: The mutation of any regulator that finely regulates the Nod Factor production causes an increase of Nod Factor gene expression, among other changes in the gene expression pattern, and in consequence an overproduction of these molecules. These changes provoke a partial impairment in symbiosis with soybean, its natural host, but on the other hand improve the nodulation effectiveness with L. burttii and allow the gaining the nodulation capacity with L. japonicus Gifu, where the wild type strain is not able to stablish an effective symbiosis. The infection mode analysis revealed that these mutants switched the infection way from intercellular infection, a primitive mode, to infection threads formation, more evolved way.Conclusions: S. fredii HH103 has evolved with its natural host, soybean, to improve their symbiotic performance even though it could diminish or abolish the nodulation effectivity with other legume plants

Implementación de Nethserver para dar solución a las necesidades específicas de la compañía tecnológica

En este artículo se presentará la propuesta para implementar un servidor GNU/Linux, usando la distribución Nethserver 7.9.200. Para tal propósito se presentará el paso a paso de la instalación y configuración del servidor en una máquina virtual, seguido de esto se configurará y demostrará el funcionamiento de los servicios de: DHCP server, DNS server, controlador de dominio, servidor proxy, firewall, FTP server, Impresoras compartidas y VPN.In this article we will present the proposal to implement a GNU/Linux server, using the Nethserver 7.9.200 distribution. Step by step installation and configuration of the server in a virtual machine, followed by the configuration and demonstration of the following services: DHCP server, DNS server, domain controller, proxy server, firewall, FTP server, Shared printers and VPN

Colección de Mamíferos del Instituto Humboldt (IAvH-M)

The Mammal Collection of the Humboldt Institute is the third largest collection in the country and houses 9.471 specimens. These belong to 400 species, 212 genera, 51 families and 14 orders, from eight countries, Colombia the one with a higher representation (66,5% of species registered in the country). The best represented orders are Chiroptera, Rodentia, and Primates. The collection houses one neotype and two paratypes of Cebus albifrons albifrons, a paratype of Aotus hershkovitzi and a paratype of Vampyressa sinchi. The collection has been a benchmark for the study of the Colombian mammals and the Institute continues its effort to improve the curatorial status and the information associated to the specimens.La colección de mamíferos del Instituto de Investigación de Recursos Biológicos Alexander von Humboldt es la tercera colección de mayor número de especímenes en el país con 9.471 determinados en 400 especies, 212 géneros, 51 familias y 14 órdenes, procedentes de ocho países, siendo Colombia el de mayor representatividad (66,5% de la diversidad registrada para el país en este grupo). Los órdenes mejor representados son Chiroptera, Rodentia y Primates. Alberga un neotipo y dos paratipos de Cebus albifrons albifrons, un paratipo de Aotus hershkovitzi y un paratipo de Vampyressa sinchi. La colección ha sido un referente para el estudio de mamíferos colombianos y se continúan realizando esfuerzos para mejorar el estado curatorial y la información asociada a los especímenes

Effect of different quality irrigation water on the growth, mineral concentration and physiological parameters of Viburnum tinus plants

Treated wastewater may be considered an alternative source of water and fertilizer nutrients for landscape plants. However, NaCl, the principal compound in this water, can be detrimental to plants. Viburnum tinus plants were submitted for 4 months to 4 irrigation treatments with water from different sources: control (Control) (EC < 0.9 dS m-1); NaCl solution (NaCl) (EC = 4 dS m-1); irrigation water normally used in the area (IW) (EC = 1.2-1.8 dS m-1) and reclaimed water (RW) (EC = 4 dS m-1). During a recovery period of two months, all the plants were irrigated with the control water. The results showed that biomass was affected in NaCl, IW and RW treatments, both leaf area and height decreased at the end of saline period. These changes were more pronounced in the NaCl treatment, which also caused a decrease in stem diameter and root/shoot ratio. The similar growth alterations founded after the recovery period showed that salts continued to be present in the substrate. Compared with the control, NaCl and RW plants showed a greater rate of Na+ and Cl- absorption by roots. Stem water potential was mainly affected by the NaCl treatment in the last weeks of the saline period. Through the experiment, the stomatal conductance and photosynthesis values were the lowest in plants that received the highest amount of salts, especially NaCl treatment which was the only treatment that did not recover at the end of experiment. Plants of the IW treatment showed slight changes in stomatal conductance and photosynthetic rate with respect to the control, although the reduction in the growth and size of these plants suggests that slight increases in EC could be very toxic for this species. Hence, using different sources of water with similar EC, (NaCl and RW) it is important to know the exact composition, since the toxic effects produced by high concentrations of Na+ and Cl- might be offset by the effect of other ions like magnesium, potassium and phosphorus. In the physicochemical analysis of water, the highest concentrations of these ions were observed in RW and as consequence, their concentrations in plants were not reduced by the Na+ and Cl- effect, phosphorus even increased, improving the plant nutritional balance.This work was supported by the projects: CICYT (AGL 2008- 05258-CO2-1-2- AGR and AGL 2011-30022-CO2-01-02), Fundación Séneca (15356/PI/10) and Vías y Construcción, S. A. (CDTI IDI-20101191).Peer Reviewe

Transcriptomic studies of the effect of nod gene-inducing molecules in rhizobia: Different weapons, one purpose

Simultaneous quantification of transcripts of the whole bacterial genome allows the analysis of the global transcriptional response under changing conditions. RNA-seq and microarrays are the most used techniques to measure these transcriptomic changes, and both complement each other in transcriptome profiling. In this review, we exhaustively compiled the symbiosis-related transcriptomic reports (microarrays and RNA sequencing) carried out hitherto in rhizobia. This review is specially focused on transcriptomic changes that takes place when five rhizobial species, Bradyrhizobium japonicum (=diazoefficiens) USDA 110, Rhizobium leguminosarum biovar viciae 3841, Rhizobium tropici CIAT 899, Sinorhizobium (=Ensifer) meliloti 1021 and S. fredii HH103, recognize inducing flavonoids, plant-exuded phenolic compounds that activate the biosynthesis and export of Nod factors (NF) in all analysed rhizobia. Interestingly, our global transcriptomic comparison also indicates that each rhizobial species possesses its own arsenal of molecular weapons accompanying the set of NF in order to establish a successful interaction with host legumes.Ministerio de Economía y Competitividad BIO2016-78409-R, AGL2016-77163-

A transcriptomic analysis of the effect of genistein on Sinorhizobium fredii HH103 reveals novel rhizobial genes putatively involved in symbiosis

Sinorhizobium fredii HH103 is a rhizobial soybean symbiont that exhibits an extremely broad host-range. Flavonoids exuded by legume roots induce the expression of rhizobial symbiotic genes and activate the bacterial protein NodD, which binds to regulatory DNA sequences called nod boxes (NB). NB drive the expression of genes involved in the production of molecular signals (Nod factors) as well as the transcription of ttsI, whose encoded product binds to tts boxes (TB), inducing the secretion of proteins (effectors) through the type 3 secretion system (T3SS). In this work, a S. fredii HH103 global gene expression analysis in the presence of the flavonoid genistein was carried out, revealing a complex regulatory network. Three groups of genes differentially expressed were identified: i) genes controlled by NB, ii) genes regulated by TB, and iii) genes not preceded by a NB or a TB. Interestingly, we have found differentially expressed genes not previously studied in rhizobia, being some of them not related to Nod factors or the T3SS. Future characterization of these putative symbiotic-related genes could shed light on the understanding of the complex molecular dialogue established between rhizobia and legumes.España, Ministerio de Economía y Competitividad BIO2011-30229-C01España, Ministerio de Economía y Competitividad AGL2012-38831Junta de Andalucía, P11-CVI-7050Junta de Andalucía P11-CVI-750