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Garcia-Sanchez A.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Alonso-Rojo P.,University of Salamanca | Santos-Frances F.,University of Salamanca
Science of the Total Environment | Year: 2010

High levels of total and bioavailable As in soils in mining areas may lead to the potential contamination of surface water and groundwater, being toxic to human, plants, and animals. The soils in the studied area (Province of Salamanca, Spain) recorded a total As concentration that varied from 5.5. mg/kg to 150. mg/kg, and water-soluble As ranged from 0.004. mg/kg to 0.107. mg/kg, often exceeding the guideline limits for agricultural soil (50. mg/kg total As, 0.04. mg/kg water-soluble As). The range of As concentration in pond water was <0.001μg/l-60μg/l, with 40% of samples exceeding the maximum permissible level (10μg/l) for drinking water. Estimated bioavailable As in soil varied from 0.045. mg/kg to 0.760. mg/kg, around six times higher than water-soluble As fraction, which may pose a high potential risk in regard to its entry into food chain. Soil column leaching tests show an As potential mobility constant threatening water contamination by continuous leaching. The vertical distribution of As through soil profiles suggests a deposition mechanism of this element on the top-soils that involves the wind or water transport of mine tailings. A similar vertical distribution of As and organic matter (OM) contents in soil profiles, as well as, significant correlations between As concentrations and OM and N contents, suggests that type and content of soil OM are major factors for determining the content, distribution, and mobilization of As in the soil. Due to the low supergenic mobility of this element in mining environments, the soil pollution degree in the studied area is moderate, in spite of the elevated As contents in mine tailings. © 2010 Elsevier B.V.


Martinez-Hidalgo P.,University of Salamanca | Galindo-Villardon P.,University of Salamanca | Igual J.M.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Martinez-Molina E.,University of Salamanca
Scientific Reports | Year: 2014

Biotic interactions can improve agricultural productivity without costly and environmentally challenging inputs. Micromonospora strains have recently been reported as natural endophytes of legume nodules but their significance for plant development and productivity has not yet been established. The aim of this study was to determine the diversity and function of Micromonospora isolated from Medicago sativa root nodules. Micromonospora-like strains from field alfalfa nodules were characterized by BOX-PCR fingerprinting and 16S rRNA gene sequencing. The ecological role of the interaction of the 15 selected representative Micromonospora strains was tested in M. sativa. Nodulation, plant growth and nutrition parameters were analyzed. Alfalfa nodules naturally contain abundant and highly diverse populations of Micromonospora, both at the intra- and at interspecific level. Selected Micromonospora isolates significantly increase the nodulation of alfalfa by Ensifer meliloti 1021 and also the efficiency of the plant for nitrogen nutrition. Moreover, they promote aerial growth, the shoot-to-root ratio, and raise the level of essential nutrients. Our results indicate that Micromonospora acts as a Rhizobia Helper Bacteria (RHB) agent and has probiotic effects, promoting plant growth and increasing nutrition efficiency. Its ecological role, biotechnological potential and advantages as a plant probiotic bacterium (PPB) are also discussed.


Gonzalez J.M.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Portillo M.C.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Belda-Ferre P.,Center for Advanced Research in Public Health | Mira A.,Center for Advanced Research in Public Health
PLoS ONE | Year: 2012

The microbial world has been shown to hold an unimaginable diversity. The use of rRNA genes and PCR amplification to assess microbial community structure and diversity present biases that need to be analyzed in order to understand the risks involved in those estimates. Herein, we show that PCR amplification of specific sequence targets within a community depends on the fractions that those sequences represent to the total DNA template. Using quantitative, real-time, multiplex PCR and specific Taqman probes, the amplification of 16S rRNA genes from four bacterial species within a laboratory community were monitored. Results indicate that the relative amplification efficiency for each bacterial species is a nonlinear function of the fraction that each of those taxa represent within a community or multispecies DNA template. Consequently, the low-proportion taxa in a community are under-represented during PCR-based surveys and a large number of sequences might need to be processed to detect some of the bacterial taxa within the 'rare biosphere'. The structure of microbial communities from PCR-based surveys is clearly biased against low abundant taxa which are required to decipher the complete extent of microbial diversity in nature. © 2012 Gonzalez et al.


Sanchez Marquez S.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Bills G.F.,Fundacion MEDINA | Herrero N.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Zabalgogeazcoa I.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca
Fungal Ecology | Year: 2012

Many fungi behave as endophytes in grasses. Unlike the well known . Epichloë/. Neotyphodium species, most other endophytes are not capable of systemic colonization of plant organs, or seed transmission. The species diversity of the non-systemic endophytic mycobiota of grasses is large, dominated by ascomycetes. The relative abundance of species is very unequal, a few dominant taxa like . Acremonium, . Alternaria, . Cladosporium, . Epicoccum and . Penicillium spp., occur in many grasses and locations. In contrast, many rare species are isolated only once in endophyte surveys. The possible ecological functions of endophytes are diverse, and often unknown. Latent pathogens represent a small fraction of endophytic mycobiotas, indicating that many non-pathogenic fungal taxa are able to enter plants overriding defence reactions. Some dominant species behave as latent saprotrophs, sporulating when the host tissue dies. Endofungal viruses and bacteria occur among endophytic species, but their effect in their hosts is largely unknown. © 2011 Elsevier Ltd and The British Mycological Society.


Marquez S.S.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Bills G.F.,Fundacion Medina | Acuna L.D.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Zabalgogeazcoa I.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca
Fungal Diversity | Year: 2010

Holcus lanatus is a grass that grows in humid, often waterlogged soils in temperate zones around the world. The purpose of this work was to identify fungal endophytes associated with its roots and leaves, and to describe the diversity and spatial distribution patterns found in its mycobiota. Holcus plants were sampled at 11 locations in western and northern Spain, and endophytes were isolated from leaves and roots of each plant. Morphological and molecular methods based on the ITS1-5.8SrRNA-ITS2 sequence were used for isolate identification. In total, 134 different species were identified, 77 occurred in leaves, 79 in roots, and 22 were common to both organs. The dominant species of the mycobiota were isolated from roots and leaves, and were species generally considered as multi-host endophytes. The species richness was similar in leaves and roots, but the composition of isolates from roots varied more among locations than in leaf mycobiotas, suggesting that soil characteristics may have strongly influenced the root mycobiota. Significant variations with respect to the composition of their mycobiota among different locations indicate that beta diversity is a first order factor governing the richness and distribution of the endophytic mycobiota in grasses. © Kevin D. Hyde 2010.


Balsera M.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Uberegui E.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Schurmann P.,Laboratoire Of Biologie Moleculaire Et Cellulaire | Buchanan B.B.,University of California at Berkeley
Antioxidants and Redox Signaling | Year: 2014

Significance: The post-translational modification of thiol groups stands out as a key strategy that cells employ for metabolic regulation and adaptation to changing environmental conditions. Nowhere is this more evident than in chloroplasts - the O2-evolving photosynthetic organelles of plant cells that are fitted with multiple redox systems, including the thioredoxin (Trx) family of oxidoreductases functional in the reversible modification of regulatory thiols of proteins in all types of cells. The best understood member of this family in chloroplasts is the ferredoxin-linked thioredoxin system (FTS) by which proteins are modified via light-dependent disulfide/dithiol (S-S/2SH) transitions. Recent Advances: Discovered in the reductive activation of enzymes of the Calvin-Benson cycle in illuminated chloroplast preparations, recent studies have extended the role of the FTS far beyond its original boundaries to include a spectrum of cellular processes. Together with the NADP-linked thioredoxin reductase C-type (NTRC) and glutathione/glutaredoxin systems, the FTS also plays a central role in the response of chloroplasts to different types of stress. Critical Issues: The comparisons of redox regulatory networks functional in chloroplasts of land plants with those of cyanobacteria - prokaryotes considered to be the ancestors of chloroplasts - and different types of algae summarized in this review have provided new insight into the evolutionary development of redox regulation, starting with the simplest O2-evolving organisms. Future Directions: The evolutionary appearance, mode of action, and specificity of the redox regulatory systems functional in chloroplasts, as well as the types of redox modification operating under diverse environmental conditions stand out as areas for future study. © Copyright 2014, Mary Ann Liebert, Inc. 2014.


Balsera M.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Soll J.,Ludwig Maximilians University of Munich | Buchanan B.B.,University of California at Berkeley
Trends in Plant Science | Year: 2010

The import of chloroplast proteins synthesized in the cytosol of a plant cell is mediated by two multiprotein complexes or translocons located at the outer and inner membranes of the chloroplast envelope, respectively, TOC and TIC. These complexes integrate different signals to assure the timely transport of proteins into the chloroplast in accordance with the metabolic and developmental needs of the cell. The past few years have witnessed the emergence of redox as a regulator of the protein transport process. Here, we discuss evidence that the metabolic redox state of the chloroplast regulates the import of preproteins by altering either the activity or composition of participating transport components. It appears that, through these redox changes, chloroplasts communicate with other compartments of the plant cell. © 2010 Elsevier Ltd.


Manzano-Roman R.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Siles-Lucas M.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca
Molecular and Biochemical Parasitology | Year: 2012

MicroRNAs (miRNAs) are a recently discovered class of small non-coding RNAs that can down-regulate protein expression by specific mRNA recognition. Evidence is accumulating that the miRNAs are implicated in the course and outcome of infectious and non-infectious diseases. Both parasites specific miRNA sequences and the phenomenon of the alteration of host miRNA levels after parasite infection are known, although detailed information about the direct intervention of parasites in the alteration of host miRNA levels and how this is regulated by parasites at molecular level is still lacking. Circulating miRNAs can be detected in biological fluids as serum, saliva and others, exhibiting a good potential as non-invasive biomarkers. Their ability to function as master regulators of the gene expression and the possibility for a relative easy manipulation of the miRNA machinery and related events, coupled with their apparent lack of adverse events when administered, place miRNAs as promising targets for the treatment of diseases. Moreover, the dependence of parasites over the host cellular machinery to accomplish infection and complete their biological cycles, together with the potential manipulation of host's responses through parasite miRNAs, point out that the miRNA machinery is particularly interesting to seek for alternative therapeutic approaches against parasites. Additionally, the studies about parasitic manipulation of the host immune responses thought miRNAs could broaden our knowledge about basic aspects of the host-parasite relationships. © 2012 Elsevier B.V.


De Aldana B.R.V.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Bills G.,University of Texas Health Science Center at Houston | Zabalgogeazcoa I.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca
Fungal Diversity | Year: 2013

Grasses represent one of the Earth's most common plant groups, and natural and cultivated habitats dominated by grasses cover about 40% of the land surface. In turn, each grass species hosts multiple fungal species which can behave as endophytes. An analysis of the endophytic taxa identified in surveys conducted in 14 grass species showed that some of the most frequent taxa on each grass were also present across several host grasses. These taxa were Alternaria, Epicoccum, Cladosporium, Fusarium, and a few others. A similar analysis of airborne fungi surveyed at 41 different locations throughout the world showed that some of the most geographically widespread, and most locally frequent airborne fungi belonged to the same genera that are dominant endophytes in grasses (i.e. Cladosporium, Alternaria, Fusarium, etc.). Therefore, airborne spores of genera that are ubiquitous in grasses are common worldwide and attain high atmospheric concentrations. In addition, spores of the above mentioned fungi are also important respiratory allergens. Direct observation indicates that saprobic colonization and sporulation of non-systemic grass endophytes could become unrestrained when their host plant tissue dies. Subsequently, when appropriate environmental conditions favour sporulation on grass host surfaces, the natural cycle for airborne conidia initiates, and large numbers of these conidia disperse as inoculum for new endophytic infections. Therefore, the cycle of endophytism may be an important link between climate, plant biology and public health. © 2013 Mushroom Research Foundation.


Herrero N.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Zabalgogeazcoa I.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca
Virus Research | Year: 2011

A mixed virus infection in a strain of the endophytic and entomopathogenic fungus Tolypocladium cylindrosporum was deduced from a study of the transmission to conidia of several double-stranded RNA (dsRNA) elements. The transmission rates of each dsRNA were different, and monosporic isolates harbouring different combinations of the original set of six dsRNAs were obtained. A 5196 bp dsRNA element was sequenced and represents the genome of T. cylindrosporum virus 1 (TcV1), a new member of the genus Victorivirus in the Totiviridae family. This virus was transmitted to 81.4% of the conidia; in contrast, four dsRNAs of 3.1-3.7. kbp were transmitted only to 4.7% of the monosporic isolates obtained from the infected parental strain. These four dsRNAs did not show segregation during transmission, and one of them was shown by sequence analysis to encode an RdRp, suggesting that the four molecules might represent the whole genome of a quadripartite chrysovirus. A third possible virus with a genome of approximately 4.2. kbp was transmitted to 79.1% of the monosporic isolates produced by the infected strain. Ribavirin was used to cure T. cylindrosporum from viruses, and TcV1 was sensitive to this drug. All monosporic cultures derived from the infected strain treated with 80 and 100. μM concentrations of the drug were free of TcV1. © 2011 Elsevier B.V.

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