1,721,039 research outputs found
Exploiting Rice Blast Fungus Enzymes for Practical Applications in Plant Disease Control and Biomass Conversion
No full textThe filamentous fungus Magnaporthe oryzae is the main causal agent of rice blast disease that accounts for 10-30% yield losses per year globally. This pathogen uses a large number of carbohydrate-active and cell wall degrading enzymes to initiate the invasion in all parts of the rice plant. These enzymes are potential targets for inhibitors or molecules with antimicrobial activity. In addition, they could hold the keys to efficiently converting rice straw, the main byproduct of rice production, to fermentable sugar. Of our particular interests are polysaccharide monooxygenases (PMOs) that degrade polysaccharides in an unprecedented oxidative mechanism and can significantly boost the activity of canonical cellulases. Understanding the mechanisms and biological functions of PMOs and related polysaccharide degrading enzymes will provide the basis for developing practical applications in rice blast disease control and biomass conversion to commodity chemicals
Indirect estimation of agent-based models. An application to a simple diffusion model
No full textWe estimate an agent-based interpretation of the well-known Bass innovation diffusion model. In order to reduce the computational complexity of the estimation procedure, standard
ML techniques are used to estimate some parameters as a function of other parameters, which are then estimated by simulated moments. We prove that our estimates are consistent
and converge to the true values as population size increases. Our approach can be generalized
to the estimation of more complex agent-based models. However, a trade-off emerges between model inadequacy and data inadequacy. This is particularly severe when only aggregate information is available, as common with diffusion data
Twenty years of research on cerato-platanin family proteins: clues, conclusions, and unsolved issues
No full textTwenty years of research on cerato-platanin family proteins (CPPs) have led to some clear conclusions: CPPs are exclusively present in the fungal kingdom and possess an outstanding capacity to stimulate the immune system of plants. Recent discoveries have highlighted remarkable structural and functional similarities between CPPs and expansins, a class of non-enzymatic proteins found in both plants and microbes possessing loosening ability on the cell wall structure. Nevertheless, the determination of a biological role for CPPs in fungi is becoming a complicated puzzle to solve, since experimental data are often divergent and point to functional diversification. A general consensus appears however possible: CPPs from pathogenic and beneficial fungi may be considered as microbe-associated molecular patterns (MAMPs) and likely play a dual role, exerting functions in the fungal cell wall and/or in plant colonization. In this review, which celebrates 20 y of research on CPPs, we trace the history of these proteins and highlight experimental evidence and still unsolved issues
Corrigendum: Characterization and expression of Fusarium graminearum endo-polygalacturonases in vitro and during wheat infection
No full textFusarium graminearum cerato-platanin proteins weaken cellulosic materials and enhance cellulase activity in an expansin-like manner
No full textCerato-platanin proteins (CPPs) belong to a family of small secreted non-catalytic fungal proteins with phytotoxic activity. CPPs have been recently classified as expansin-like proteins because of structural and functional features related to plant expansins, small secreted proteins able to loosen and disrupt the non-covalent bonding networks of plant cell wall polysaccharides without enzymatic activity. The genome of Fusarium graminearum, the causal agent of Fusarium head blight disease of wheat and other cereal grains, contains two genes putatively encoding for CPPs (FgCPPs). To characterize their role, the two proteins have been heterologously expressed in yeast. Enzymatic assays have shown the ability of the recombinant FgCPPs to reduce the viscosity of a cellulose soluble derivate (carboxymethyl cellulose, CMC) mainly with a non-enzymatic activity. Indeed, differently from other fungal CPPs and similarly to expansins, FgCPPs seem trapped by cellulose and not by chitin, thus suggesting that they could interact with cellulose. The incubation of CMC with a cellulase in presence or absence of the two recombinant proteins has shown that the FgCPPs enhance cellulase activity. A double knock-out mutant deleted of both FgCPPs encoding genes produces higher cellulase activity when grown on CMC, thus suggesting that the absence of FgCPPs forces the fungus to produce more cellulase activity to compensate for the lack of expansin-like activity. Finally, the preliminary demonstration that the FgCPPs act also loosening filter paper, a natural insoluble cellulose, could suggest a possible future biotechnological application in second-generation biofuels production from agricultural lignocellulosic biomasses rich in cellulose
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A single amino acid substitution in highly similar endo-PGs from Fusarium verticillioides and related Fusarium species affects PGIP inhibition
No full textEndo-polygalacturonase (PG) may be a critical virulence factor secreted by several fungi upon plant invasion. The single-copy gene encoding PG in Fusarium verticillioides and in eight other species of the Gibberella fujikuroi complex (F. sacchari, F. fujikuroi, F. proliferatum, F. subglutinans, F. thapsinum, F. nygamai, F. circinatum, and F. anthophilum) was functionally analyzed in this paper. Both the nucleotide and amino acid sequences were highly similar among the 12 strains of F. verticillioides analyzed, as well as among those from the G. fujikuroi complex. The PGs were not inhibited by the polygalacturonase-inhibiting proteins (PGIPs) from the monocot asparagus and leek plants, but were inhibited to variable extents by bean PGIP. PGs from F. verticillioides, F. nygamai and one strain of F. proliferatum were barely inhibited. Residue 97 within PG was demonstrated to contribute to the different levels of inhibition. Together these findings provide new insights into the structural and functional relationships between the PG from the species of the G. fujikuroi complex and the plant PGIP. © 2007 Elsevier Inc. All rights reserved
Peptide-Based Biopesticides
No full textIn this presentation we describe the great potential of peptides as biopesticides. Currently Europe is greatly encouraging research in sustainable pest-management. Finding eco-friendly, effective alternatives to synthetic pesticides is of paramount importance, especially against the so-called priority pests of fruits and vegetables. For some of these pests, such as botrytis cinerea and peronospora viticola, no effective bio-alternatives to small organic molecules are available so far. Fungi belonging to the genus Trichoderma are distributed worldwide and have been used successfully in field trials against many crop pathogens. They produce peptaibols, a peculiar family of peptides, as part of their defense system against other microorganisms. Such secondary metabolites are known for their plantprotection properties: they (i) possess antimicrobial activity, (ii) act as stimulants of plant defences and growth (iii) elicit plant production of volatiles to attract natural enemies of herbivorous insects. By means of a versatile SPPS strategy, we produced several analogs of such naturally occurring peptides. With such compounds, we can circumvent both the health hazards and the unreliable effectiveness in open field connected with the use of antagonistic microorganisms as biological control agents, while keeping the biomolecules responsible for their beneficial effects. Our peptides have been tested (alone or in combination) both in vitro and in vivo against a variety of priority pests, such as the fungi Botrytis cinerea and Penicillum italicum, and the bacterium Pectobacterium carotovorum. We identified several peptaibol analogs with a broad-spectrum activity as biopesticides, able to completely inhibit the growth of B. cinerea and many other pathogens for over a week at low micromolar concentrations
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