1,721,004 research outputs found
Characterization of endopolygalacturonase of species belonging to the Gibberella fujikuroi complex
No full textThe Gibberella fujikuroi complex includes toxigenic and pathogenic fungal species able to produce disease on several economically important crops. In order to understand the involvement of the endopolygalacturonase (endo-PG) in the infection process we have first purified the endo-PG produced in culture by eight species (from two to four isolates of Fusarium verticillioides, F. sacchari, F. fujikuroi, F. proliferatum, F. subglutinans, F. thapsinum, F. nygamai, F. circinatum) belonging to the complex, and then cloned the corresponding genes. The coding sequence of the endo-pg gene permitted to distinguish clearly the different species according to the classification obtained with the partial sequence of the translation elongation factor (TEF), a molecular marker widely used to distinguish identify Fusarium species. The deduced aminoacidic sequence of endo-PGs were very similar among the species and quite identical within the species. The endo-PGs displayed similar properties when assayed against different substrates but showed diverse behaviors in the presence of plant inhibitors (PGIP). In particular, all endo-PGs were not inhibited by PGIP from monocot plants (like aparagus and maize) but presented various degree of inhibition when assayed against the bean PGIP, with the endo-PG from F. verticillioides being the less inhibited. Considering that many species of the G. fujikuroi complex are pathogens of monocot plants, their endo-PG appears particularly adapted to overcome the hindrance of the host PGIPs
Endo-PGs from species of the Gibberella fujikuroi complex provide new insight into the PG-PGIP interaction
No full textSeveral Fusarium species of the Gibberella fujikuroi complex are toxigenic and able to induce diseases on many crops, especially cereals. At early stages of the infection process, these fungi produce endo-polygalacturonase (PG) activity which degrades the host cell wall pectic polymers. Plants, on the other hand, contain polygalacturonase-inhibiting proteins (PGIPs) in their tissues which may contrast the fungal infection by inhibiting the PG activity. We observed that the PGs from several species of the Gibberella fujikuroi complex (F. verticillioides, F. sacchari, F. fujikuroi, F. proliferatum, F. subglutinans, F. thapsinum, F. anthophilum, F. nygamai, F. circinatum) are not inhibited by PGIPs extracted from asparagus and leek monocot plants. Instead, these PGs were inhibited to variable extents by the PGIP extracted from bean. The PGs ranked into four groups of inhibition when assayed against the bean PGIP. Specifically, the PGs from F. verticillioides and F. nygamai were the least inhibited and those from F. thapsinum were low inhibited; the PGs from F. sacchari, F. fujikuroi and F. proliferatum were inhibited at an intermediate level, while the PGs from F. anthophilum, F. circinatum and F. subglutinans were the most inhibited. The genes encoding these fungal PGs were cloned, and the multiple alignments of the deduced amino acid sequences allowed identifying the few amino acid substitutions likely involved in the different binding with the bean PGIP. Site-directed mutagenesis experiments showed that the amino acid in position 122 is crucial for recognition of the Fusarium PGs by the bean PGIP
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
First report of Olpidium virulentus, O. bornovanus, O. brassicae on cucumber in Sardinia, Italy
No full textFusaHelp. A web site program for the morphological identification of Fusarium species
Full text linkFusarium is one of the most important phytopathogenic fungi of agricultural and human concern. More than 300 species have been described, many of which are pathogenic to important crops, flowers, forest trees, animals, and humans. Species belonging to this genus have been detected in all environments: grassland, desert, littoral, agricultural, alpine zones, aquatic, man-made, and hospitals. Despite the importance of molecular techniques for the identification of a fungal species, morphological criteria still have an important role, including for Fusarium species, for which morphological identification of species requires adequate training and experience. In this paper, we present FusaHelp, a computer-based, user-friendly tool for the morphological identification of common Fusarium species, based on the wide experience of the authors who have devoted most of their scientific careers to the identification and characterization of these species. The web-location of FusaHelp (https://www.fusahelp.com) will greatly facilitate morphological identification and is intended to provide support for all those people who work with this important genus and need a quick clue on the identification, even incomplete, of the Fusarium species that they are working with. © 2023, The Author(s)
Characterisation of isolates of Phoma tracheiphila by RAPD-PCR, microsatellite-primed PCR and rDNA ITS1/ITS2 sequencing and development of specific primers for in planta detection
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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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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