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Coexpression of fungal cell wall-modifying enzymes reveals their additive impact on arabidopsis resistance to the fungal pathogen, Botrytis cinerea
Full text linkThe plant cell wall (CW) is an outer cell skeleton that plays an important role in plant growth and protection against both biotic and abiotic stresses. Signals and molecules produced during host–pathogen interactions have been proven to be involved in plant stress responses ini-tiating signal pathways. Based on our previous research findings, the present study explored the possibility of additively or synergistically increasing plant stress resistance by stacking beneficial genes. In order to prove our hypothesis, we generated transgenic Arabidopsis plants constitutively overexpressing three different Aspergillus nidulans CW-modifying enzymes: a xylan acetylesterase, a rhamnogalacturonan acetylesterase and a feruloylesterase. The two acetylesterases were expressed either together or in combination with the feruloylesterase to study the effect of CW polysaccharide deacetylation and deferuloylation on Arabidopsis defense reactions against a fungal pathogen, Botrytis cinerea. The transgenic Arabidopsis plants expressing two acetylesterases together showed higher CW deacetylation and increased resistance to B. cinerea in comparison to wild-type (WT) Col-0 and plants expressing single acetylesterases. While the expression of feruloylesterase alone compromised plant resistance, coexpression of feruloylesterase together with either one of the two acetylesterases restored plant resistance to the pathogen. These CW modifications induced several defense-related genes in uninfected healthy plants, confirming their impact on plant resis-tance. These results demonstrated that coexpression of complementary CW-modifying enzymes in different combinations have an additive effect on plant stress response by constitutively priming the plant defense pathways. These findings might be useful for generating valuable crops with higher protections against biotic stresses
The 3-D structure of PGIP reveals a binding site mediating interaction with pectins
No full textSorrento, Ital
ALTERATIONS OF CELL WALL STRUCTURE AND INTEGRITY IMPROVE RESISTANCE TO PATHOGENS
No full textCell wall modifying enzymes (CWMEs) are expressed by microbial pathogens during invasion to penetrate the cell wall barrier. Plants sense loss of cell wall integrity and trigger defenses leading to an improved resistance to pathogens. The expression of CWMEs or their inhibit ors in planta represents a useful tool not only to improve resistance to pathogens but also to investigate therole of the altered cell wall structure and integrity in plant-pathogen interactions. Loss of homogalacturonan integrity in tobacco and Arabidopsis obtained by expressing a fungal endopolygalacturonase induces specific defense responses and enhances plant resistance to Botrytis cinerea and Pseudomonas syringae. Ectopic expression of fungal xylan or pectins acetylesterases in Arabidopsis and Brachipodium triggers specific responses leading to higher resistance to
B. cinerea and Bipolaris sorokiniana, respectively. A targeted inhibition of the susceptibility fact or pectin methylesterase (PME) through the overexpression of PME inhibitors (PMEI) or the knockout of a specific PME gene causes an increased esterification of pectin and a concomitant reduced susceptibility toB. cinerea and Pectobacterium carotovorum. Moreover, the spreading of two Tobamovirus is retarded in tobacco and Arabidopsis plants overexpressing PMEI
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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