Microbiome engineering to improve biocontrol and plant growth-promoting mechanisms

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.micres.2018.01.005 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/A plant microbiome includes a microbial community that typically interacts extensively with a plant. The plant microbiome can survive either inside or outside of plant tissues, performing various plant beneficial activities including biocontrol of potential phytopathogens and promotion of plant growth. An important part of the plant microbiome includes plant growth-promoting bacteria (PGPB) that commonly reside in the rhizosphere and phyllosphere, and as endophytic bacteria (inside of plant tissues). As new plant microbiome-manipulating strategies have emerged in recent years, we have critically reviewed relevant literature, chiefly from the last decade. We have analysed and compared the rhizosphere, phyllosphere and endosphere as potential ecosystems for manipulation, in order to improve positive interactions with the plant. In addition, many studies on the bioengineering of the endophyte microbiome and its potential impact on the core microbiome were analysed with respect to five different strategies, including host mediated and multi-generation microbiome selection, inoculation into soil and rhizosphere, inoculations into seeds or seedlings, tissue atomisation and direct injection into tissues or wounds. Finally, microbiome engineering presents a feasible strategy to solve multiple agriculture-associated problems in an eco-friendly way.Fundación Santoy

Similaridad del nicho ecológico de Pinus montezumae y P. pseudostrobus (Pinaceae) en México: implicaciones para la selección de áreas productoras de semillas y de conservación

Background and Aims: Ecological niche models have been used to understand how species can change or persist in an environmental and geographical space over time. The aims of the study were i) to model the ecological niche of Pinus montezumae and Pinus pseudostrobus in Mexico, ii) to evaluate and compare the similarity and equivalence of niche suitability between the distribution areas of both species, and iii) to propose potential geographic zones for the delimitation of seed-producing and conservation areas for each species.Methods: We used geographical data on distribution of species and climatic, topographic, elevation and soil data as environmental predictors, which were modeled based on the Maximum Entropy algorithm. The parameters of similarity (I) and equivalence (D) were estimated to know the degree of overlap of the niche of the species. For the selection of seed areas, environmental data were used that defined the distribution of each species and dasometrics of the National Forest and Soil Inventory (INFyS).Key results: The models show that the two species have similar areas of high suitability, distributed in the Trans-Mexican Volcanic Belt and the Sierra Madre del Sur. The highest contribution to the models for Pinus pseudostrobus were the variables average annual temperature (41.3%) and total annual rainfall (14.3%), whereas the soil (31.1%) and altitude (29%) were determinants in P. montezumae. The niche overlap analysis indicates that the observed value of equivalence (D=0.430) is less than the similarity value (I=0.610), suggesting that the species have a similar niche but that this is not equivalent, which could be in the process of diversification.Conclusions: The suitability of the ecological niche is similar for the two pine species, but it is not equivalent as they present differential environmental variables. These results have implications for the selection of potential areas for seed production and conservation of each species.Antecedentes y Objetivos: Los modelos de nicho ecológico se han usado para entender de qué manera las especies pueden cambiar o persistir en un espacio ambiental y geográfico a lo largo del tiempo. Los objetivos del presente estudio fueron i) modelar el nicho ecológico de P. montezumae y P. pseudostrobus en México, ii) evaluar y comparar la similaridad y equivalencia de la idoneidad del nicho entre las áreas de distribución de las dos especies, y iii) proponer zonas geográficas potenciales para la delimitación de áreas productoras de semillas y conservación para cada especie.Métodos: Se usaron datos geográficos para predecir la distribución de especies y climáticos topográficos y edáficos como predictores ambientales, fueron modelados con base en el algoritmo de Máxima Entropía. Se estimaron parámetros de similaridad (I) y equivalencia (D) para conocer el grado de traslape del nicho. Para la selección de áreas semilleras se usaron los datos ambientales que definieron la distribución de cada especie y dasométricos del Inventario Nacional Forestal y de Suelos (INFyS).Resultados clave: Los modelos muestran que las dos especies presentan zonas muy similares de alta idoneidad, distribuidas en la Faja Volcánica Transmexicana y en la Sierra Madre del Sur. Las mayores contribuciones al modelo de Pinus pseudostrobus fueron las variables temperatura promedio anual (41.3%) y precipitación total anual (14.3%), mientras que el suelo (31.1%) y la altitud (29%) fueron determinantes para el modelo de P. montezumae. El traslape de nicho presenta un valor observado de equivalencia (D=0.430) menor al de similaridad (I=0.610), sugiriendo que las especies tienen un nicho similar, pero que este no es equivalente en su totalidad, el cual podría estar en proceso de diversificación.Conclusiones: La idoneidad del nicho ecológico es similar para las dos especies de pino, pero no es equivalente al presentar variables ambientales diferenciales. Estos resultados tienen implicaciones para la selección potencial de áreas productoras de semillas y conservación para cada especie

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Influencia de la maduración del fruto de Arbutus xalapensis kunth sobre la germinación de semillas y embriones cigóticos

The aim of this study was to determine the effect of fruit ripeness of in vitro germination of seeds and zygotic embryos of Arbutus xalapensis Kunth. Fruits were collected from 10 trees in each of the two study sites and were classified according to their size and weight in 10 states into three groups characterized by the color of the fruit: 1 to 6 dark green fruits (DGF), 7 and 8 yellow-green fruits (YGF) and 9 and 10 orange-red fruits (ORF). 50 seeds of each state were selected and placed on MS medium to evaluate their germination. The experiment was repeated two times and the results were submitted to Tukey's analysis of mean comparison which indicated that the three groups have different characteristics related to fresh weight and diameter (P ≤ 0.05), with an average of 6.3 g and 0.21 mm for DGF, 9.5 g and 0.46 mm for YGF and 10.8 g and 0.70 mm for ORF. The stereomicroscopic analysis showed that all states have seed maturation and embryos; states one to four embryos have developed, and in the states 5 to 10, fruits contain a greater number of seeds with embryos developed and higher germination (7.6 to 8.8). Therefore, is proposed the use of ripening fruit from stages 5 to 10 for right germination of seeds of strawberry tree, while for zygotic embryos is necessary to carry out studies of culture media for its germination.En este trabajo se determinó el efecto del estado de maduración del fruto en la germinación in vitro de semillas y embriones cigóticos de Arbutus xalapensis Kunt. Se colectaron frutos de 10 árboles en cada uno de los dos sitios de estudio y se clasificaron según su tamaño y peso dentro de tres grupos caracterizados por el color del fruto: 1 a 6 frutos verde oscuro (FVO), 7 y 8 frutos verde-amarillo (FVA), y 9 y 10 frutos naranja-rojizo (FNR). De cada estado se seleccionaron 50 semillas y se colocaron en medio MS para evaluar su germinación. El experimento se repitió dos veces y los resultados obtenidos fueron sometidos a un análisis de comparación de medias de Tukey el cual indicó que los tres grupos de frutos presentan características de peso fresco y diámetro diferentes (P ≤ 0.05), con un promedio de 6.3 g y de 0.21 mm para FVO, 9.5 g y 0.46 mm para FVA y 10.8 g y 0.70 mm para FNR. El análisis de microscopía estereoscópica demostró que todos los estados de maduración presentan semillas y embriones; los estados 1 al 4 presentan embriones no desarrollados, y en los estados 5 al 10 los frutos contienen un mayor número de semillas con embriones desarrollados y con una mayor germinación (7.6 a 8.8 semillas/unidad experimental). Se propone el uso de semillas provenientes de frutos de los estados de maduración 5 al 10 para la germinación adecuada de semillas de madroño, mientras que para los embriones cigóticos es necesario realizar estudios de prueba de medios de cultivo para su germinación

Aumento de tolerancia de Casuarina equisetifolia a cloruro de sodio mediado por pseudomonas fluorescens

The use of tolerant species and beneficial microorganisms is an alternative in the recovery of saline soils. The objective of this research was to evaluate the efficiency of casuarina as a species tolerant to salinity and the effect of Pseudomonas fluorescens on this condition. This research tested salinity tolerance of casuarina and the additive effect of Pseudomonas fluorescens inoculation. The effect of sodium chloride (NaCl) on the casuarina germination was determined, the soil-plant interaction was analyzed on its tolerance to salinity and the effect of Pseudomonas flourescens strains (UM16, UM240, UM256 and UM270) on increased NaCl tolerance in casuarina. Results show that casuarina seed germination was delayed proportionally to NaCl concentration. NaCl tolerance was observed in dry biomass weight which decreased 3,50 to 23,48% in the roots and 1,18 to 30,66% in the aerial parts when compared to the absolute control. Innoculation of P. fluorescens strain UM256 increased dry biomass weight in the root and aerial part by 10,06 and 18,70%, respectively, when compared to the NaCl-treated control. In conclusion, the best result was for the plants that were inoculated with P. fluorescens strain UM256 which increases the tolerance of the plants to soil salinity conditions.El uso de especies tolerantes y microorganismos benéficos es una alternativa en la recuperación de suelos salinos. El objetivo de esta investigación fue evaluar la eficiencia de casuarina como especie tolerante a la salinidad y el efecto de Pseudomonas fluorescens sobre ésta capacidad en condiciones de invernadero. Se determinó el efecto del cloruro de sodio (NaCl) sobre la germinación de casuarina, se analizó la interacción suelo-planta sobre su tolerancia a la salinidad y el efecto de Pseudomonas  fluorescens cepas: UM16, UM240, UM256 y UM270 sobre el aumento de la tolerancia al NaCl. Los resultados obtenidos demuestran que la germinación de semillas de casuarina se retrasó en forma directamente proporcional a la concentración de NaCl. La tolerancia de la planta a NaCl se reflejó en materia seca, con valores de 3,50 a 23,48%  y 1,18 a 30,66% por debajo del testigo absoluto para raíz y parte aérea, respectivamente. La cepa UM256 de P. fluorescens incrementó la materia seca de raíz y parte aérea entre 10,06 y 18,70% con relación al testigo con NaCl. En conclusión, el mejor resultado fue para las plantas que fueron inoculadas con P. fluorescens cepa UM256 la cual aumenta la tolerancia de las plantas ante condiciones de salinidad del suelo