The Symbiosis Interactome: a computational approach reveals novel components, functional interactions and modules in Sinorhizobium meliloti

<p>Abstract</p> <p>Background</p> <p><it>Rhizobium</it>-Legume symbiosis is an attractive biological process that has been studied for decades because of its importance in agriculture. However, this system has undergone extensive study and although many of the major factors underpinning the process have been discovered using traditional methods, much remains to be discovered.</p> <p>Results</p> <p>Here we present an analysis of the 'Symbiosis Interactome' using novel computational methods in order to address the complex dynamic interactions between proteins involved in the symbiosis of the model bacteria <it>Sinorhizobium meliloti </it>with its plant hosts. Our study constitutes the first large-scale analysis attempting to reconstruct this complex biological process, and to identify novel proteins involved in establishing symbiosis. We identified 263 novel proteins potentially associated with the Symbiosis Interactome. The topology of the Symbiosis Interactome was used to guide experimental techniques attempting to validate novel proteins involved in different stages of symbiosis. The contribution of a set of novel proteins was tested analyzing the symbiotic properties of several <it>S. meliloti </it>mutants. We found mutants with altered symbiotic phenotypes suggesting novel proteins that provide key complementary roles for symbiosis.</p> <p>Conclusion</p> <p>Our 'systems-based model' represents a novel framework for studying host-microbe interactions, provides a theoretical basis for further experimental validations, and can also be applied to the study of other complex processes such as diseases.</p

Helping Legumes under Stress Situations: Inoculation with Beneficial Microorganisms

In the upcoming years, legume crops will be subjected to multiple, diverse, and overlapping environmental stressors (raise in global temperatures and CO2, drought, salinity, and soil pollution). These factors will menace legume productivity and food quality and security. In this context, tolerant plant growth promoting rhizobacteria (PGPR) are useful biotechnological tools to assist legume establishment and growth. In this chapter, tolerant PGPR able to promote legume growth will be revised. Besides, in the era of -omics, the mechanisms underlying this interaction are being deciphered, particularly transcriptomic, proteomic, and metabolomic changes modulated by PGPR, as well as the molecular dialog legume-rhizobacteria

Modeling the Impact of Traffic Conditions and Bicycle Facilities on Cyclists\u27 On-Road Stress Levels

Past research efforts have shown that cyclists’ safety, stress, and comfort levels greatly affect the routes chosen by cyclists and cycling frequency. Some researchers have tried to categorize cyclists’ levels of traffic stress utilizing data that can be directly measured in the field, such as the number of motorized travel lanes, motorized vehicle travel speeds, and type of bicycle infrastructure. This research effort presents a novel approach: real-world, on-road measurements of physiological stress as cyclists travel across different types of bicycle facilities at peak and off-peak traffic times. By matching videos with stressful events, it was possible to observe the circumstances of those stressful events. The stress data was normalized, and the method was carefully validated by a detailed analysis of the stress measurements. Novel statistical results from a multi-subject study quantifies the impact of traffic conditions, intersections, and bicycle facilities on average stress levels

Removal of copper from aqueous solutions by rhizofiltration using genetically modified hairy roots expressing a bacterial Cu-binding protein

The aim of this work was to develop a biotechnological tool to hyperaccumulate high copper (Cu) concentrations from wastewaters. Transgenic tobacco hairy roots were obtained by expressing, either the wild-type version of the gene copC from Pseudomonas fluorescens in the cytoplasm of plant cells (CuHR), or a modified version targeted to the vacuole (CuHR-V). Control hairy roots transformed with the empty vector (HR) were also generated. The roots were incubated in the presence of solutions containing Cu (from 1 to 50 mM). At 5 mM external copper, transgenic hairy roots accumulated twice the amount of copper accumulated by control hairy roots. However, at 50 mM Cu, accumulation in both transgenic and control roots reached similar values. Maximum Cu accumulation achieved by transgenic hairy roots was 45,000 µg g−1 at 50 mM external Cu. Despite the high Cu accumulation, transgenic hairy roots, particularly CuHR-V, showed less toxicity symptoms, in correlation with lower activity of several antioxidant enzymes and lower malondialdehyde (MDA) levels. Moreover, CuHR-V roots displayed low values of the oxidative stress index (OSI)–a global parameter proposed for oxidative stress–indicating that targeting CopC to the vacuole could alleviate the oxidative stress caused by Cu. Our results suggest that expressing copC in transgenic hairy roots is a suitable strategy to obtain Cu-hyperaccumulator hairy roots with less toxicity stress symptoms. Abbreviations: APX: ascorbate peroxidase; ATSDR: Agency for Toxic Substances and Disease Registry (U.S.); BCF: bioconcentration factor; CuHR: copper-hairy roots; EDTA: ethylenediamine tetracetic acid; EPA: Environmental Protection Agency (U.S.); GSH: glutathione; HM: heavy metals; HR: control hairy roots; ICP-OES: Inductively Coupled Plasma/Optical Emission Spectrometry; MDA: malondialdehyde; NBT: nitroblue tetrazolium; OD: optical density; OSI: oxidative stress index; PCR: polymerase chain reaction; PVP: polyvynilpirrolidone; PX: peroxidase; ROS: reactive oxygen species; SOD: superoxide dismutase.Fil: Perez Palacios, Patricia. Universidad de Sevilla; EspañaFil: Agostini, Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; ArgentinaFil: Ibañez, Sabrina Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; ArgentinaFil: Talano, Melina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; ArgentinaFil: Rodríguez Llorente, Ignacio D.. Universidad de Sevilla; EspañaFil: Caviedes, Miguel A.. Universidad de Sevilla; EspañaFil: Pajuelo, Eloísa. Universidad de Sevilla; Españ

Engineering Copper Hyperaccumulation in Plants by Expressing a Prokaryotic <i>copC</i> Gene

In this work, engineering Cu-hyperaccumulation in plants was approached. First, the <i>copC</i> gene from Pseudomonas sp. Az13, encoding a periplasmic Cu-binding protein, was expressed in Arabidopsis thaliana driven by the <i>CaMV35S</i> promoter (transgenic lines 35S-copC). 35S-copC lines showed up to 5-fold increased Cu accumulation in roots (up to 2000 μg Cu. g^–1) and shoots (up to 400 μg Cu. g^–1), compared to untransformed plants, over the limits established for Cu-hyperaccumulators. 35S lines showed enhanced Cu sensitivity. Second, <i>copC</i> was engineered under the control of the <i>cab1</i> (chlorophyll a/b binding protein 1) promoter, in order to drive <i>copC</i> expression to the shoots (transgenic lines cab1-copC). cab1-copC lines showed increased Cu translocation factors (twice that of wild-type plants) and also displayed enhanced Cu sensitivity. Finally, subcellular targeting the CopC protein to plant vacuoles was addressed by expressing a modified <i>copC</i> gene containing specific vacuole sorting determinants (transgenic lines 35S-copC-V). Unexpectedly, increased Cu-accumulation was not achievedneither in roots nor in shootswhen compared to 35S-copC lines. Conversely, 35S-copC-V lines did display greatly enhanced Cu-hypersensitivity. Our results demonstrate the feasibility of obtaining Cu-hyperaccumulators by engineering a prokaryotic Cu-binding protein, but they highlight the difficulty of altering the exquisite Cu homeostasis in plants

Tolerancia al mercurio de variedades de Lupinus albus inoculadas con Bradyrhizobium en suelos contaminados por mercurio

Trabajo presentado en la III Conferencia Iberoamericana de Interacciones Beneficiosas Microorganismo-Planta-Ambiente (IBEMPA), celebrada en Lima (Perú), del 6 al 10 de noviembre de 2017En nuestro grupo se está estudiando el potencial fitorremediador de suelos contaminados por metales pesados de la simbiosis leguminosa-rizobio. Se ha demostrado, en cultivo semi-hidropónico y concentraciones entre 0 y 200 ¿M de HgCl2 en la solución de riego, que la inoculación de plantas de altramuz (L. albus) con la cepa L-7AH de Bradyrhizobium canariense, tolerante al mercurio, confiere a las plantas la capacidad de desarrollarse en presencia de este metal pesado y acumularlo en altas concentraciones, especialmente en raíces y nódulos. Crecimiento, eficiencia fotosintética y actividad nitrogenasa de las plantas inoculadas con L-7AH eran similares a los de las plantas control (sin Hg), mientras que en las inoculadas con la cepa sensible, L-3, todos los parámetros disminuían significativamente y apenas acumulaban Hg. Estos resultados sugerían que la simbiosis L. albus-B. canariense L-7AH podría ser útil para la fitorremediación, mediante fitoestabilización, de suelos contaminados por Hg. Para evaluar la capacidad fitorremediadora de estas plantas, se utilizaron suelos de las localidades de Almadenejos y Las Cuevas (Ciudad Real, España) con diferentes contenidos totales en Hg (22 y 2.6 g kg-1, respectivamente), que se mezclaron con vermiculita (1:1) para evitar su compactación. Se sembraron semillas de altramuz de las variedades G1 y N1 y se inocularon con B. canariense L-7AH, o L-3, o no se inocularon. Tras 6 semanas de riego con agua estéril, todas las plantas mostraban un aspecto similar. Se midieron parámetros de crecimiento, fotosíntesis, actividades enzimáticas del metabolismo antioxidante y nitrogenasa, sin encontrar diferencias significativas. El análisis físico-químico de los suelos, sin embargo, mostró que éstos presentaban una gran diferencia en su pH, siendo 6.9 el de Almadenejos y 5.1 el de Las Cuevas, lo cual afecta al porcentaje de Hg ligado a ácidos húmicos que es del 2.1% y del 13.1%, respectivamente. En esas condiciones, la concentración de Hg biodisponible es probablemente muy similar en ambos suelos, lo que explicaría los resultados del presente ensayo.Agradecemos la financiación a MINECO (AGL2013-40758-R) y CSIC i-COOP (2016SU0005)

Targeting Acr3 from: Ensifer medicae to the plasma membrane or to the tonoplast of tobacco hairy roots allows arsenic extrusion or improved accumulation. Effect of acr3 expression on the root transcriptome

Transgenic tobacco hairy roots expressing the bacterial arsenite efflux pump Acr3 from Ensifer medicae were generated. The gene product was targeted either to the plasma membrane (ACR3 lines) or to the tonoplast by fusing the ACR3 protein to the tonoplast integral protein TIP1.1 (TIP-ACR3 lines). Roots expressing Acr3 at the tonoplast showed greater biomass than those expressing Acr3 at the plasma membrane. Furthermore, higher contents of malondialdehyde (MDA) and RNA degradation in ACR3 lines were indicative of higher oxidative stress. The determination of ROS-scavenging enzymes depicted the transient role of peroxidases in ROS detoxification, followed by the action of superoxide dismutase during both short- and medium-term exposure periods. Regarding As accumulation, ACR3 lines accumulated up to 20-30% less As, whereas TIP-ACR3 achieved a 2-fold increase in As accumulation in comparison to control hairy roots. Strategies that presumably induce As uptake, such as phosphate deprivation or dehydration followed by rehydration in the presence of As, fostered As accumulation up to 10 800 μg g-1. Finally, the effects of the heterologous expression of acr3 on the root transcriptome were assessed. Expression at the plasma membrane induced drastic changes in gene expression, with outstanding overexpression of genes related to electron transport, ATP synthesis and ATPases, suggesting that As efflux is the main detoxification mechanism in these lines. In addition, genes encoding heat shock proteins and those related to proline synthesis and drought tolerance were activated. On the other hand, TIP-ACR3 lines showed a similar gene expression profile to that of control roots, with overexpression of the glutathione and phytochelatin synthesis pathways, together with secondary metabolism pathways as the most important resistance mechanisms in TIP-ACR3, for which As allocation into the vacuole allowed better growth and stress management. Our results suggest that modulation of As accumulation can be achieved by subcellular targeting of Acr3: expression at the tonoplast enhances As accumulation in roots, whereas expression at the plasma membrane could promote As efflux. Thus, both approaches open the possibilities for developing safer crops when grown on As-polluted paddy soils, but expression at the tonoplast leads to better growth and less stressed roots, since the high energy cost of As efflux likely compromises growth in ACR3 lines.Fil: Pérez Palacios, Patricia. Universidad de Sevilla. Facultad de Farmacia; España. British American Tobacco; Reino Unido. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; ArgentinaFil: Funes Pinter, Mariano Iván. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Biotecnología Ambiental y Salud - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Cordoba. Instituto de Biotecnología Ambiental y Salud; ArgentinaFil: Agostini, Elizabeth. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Biotecnología Ambiental y Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Cordoba. Instituto de Biotecnología Ambiental y Salud; ArgentinaFil: Talano, Melina Andrea. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Biotecnología Ambiental y Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Cordoba. Instituto de Biotecnología Ambiental y Salud; ArgentinaFil: Ibañez, Sabrina Guadalupe. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Biotecnología Ambiental y Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Cordoba. Instituto de Biotecnología Ambiental y Salud; ArgentinaFil: Humphry, Matt. British American Tobacco; Reino UnidoFil: Edwards, Kieron. British American Tobacco; Reino UnidoFil: Rodríguez Llorente, Ignacio. Universidad de Sevilla; EspañaFil: Caviedes, Miguel A.. Universidad de Sevilla; EspañaFil: Pajuelo, Eloísa. Universidad de Sevilla; Españ