1,720,961 research outputs found
Enhancement of PR1 and PR5 gene expressions by chitosan treatment in kiwifruit plants inoculated with Pseudomonas syringae pv. Actinidiae.
No full textKiwifruit, with a production of more than 1.5 million tons/year in the world, must be protected against
attack by its most common pathogen. Following the European guidelines on the substitution of pesticides by
safer alternatives, the aim of this work was to verify if kiwifruit plants are able to better resist pathogen infections
through the use of chitosan, a biodegradable compound and a well-known elicitor of Systemic Acquired
Resistance (SAR). To evaluate the chitosan’s elicitation effect in plant during the treatment period, two genes
involved in the metabolic pathway of SAR were chosen, Pathogenesis Related Protein 1 and 5 (PRs). Primers for both genes were designed and validated and chitosan’s elicitation effect was tested in qRT-PCR. Elicitation of SAR was first evaluated in a model system with plants cultured in vitro and subsequently in 2 year old plants
belonging to two different species (Actinidia chinensis Planch. and A. deliciosa (A. Chev.) C.F. Liang & A.R.
Ferguson). To evaluate the effects of chitosan elicitation in the presence of the pathogen attack, the 2-year-old
plants were inoculated with the bacterium Pseudomonas syringae pv. actinidiae. Micropropagated
kiwifruit plants were a good model to test molecular markers for SAR onset. Moreover, PR1 and PR5 have
also shown to be suitable candidates for the detection of the plant immune system activation. In this study, chitosan elicited a systemic response in kiwi plants with intensity comparable to other well-known signalling
compounds (salicylic acid, methyl jasmonate or ethylene), as shown by the changes in PR1’s and PR5’s
transcription profiles. The data obtained by chitosan treatments in in vitro cultures were confirmed in plants
grown in greenhouse, in which, moreover, the combination of chitosan treatment and the bacterial inoculum had the greatest effect on PRs synthesis. This study also proved that chitosan, leading to an increased expression of both PRs, has a role in kiwifruit defense reactions
A sustainable approach for Actinidia pest management
No full textCurrent strategies to contain emerging diseases in growing kiwifruits involve the massive use of pesticides. Their high doses applied increase the risk of pollution with consequences to the soil fauna and human health. In order to reduce the negative impact on the environment, the European Economic Community adopted a new legislative framework on pesticides to foresee the replacement of chemical substances with natural ones. Following this European trend, the aim of this work is to improve the quality production of Actinidia by growing plants able to better resist pathogen infection through the use of chitosan, a natural and biodegradable, well-known elicitor of Systemic Acquired Resistance (SAR).
Two years old plants of yellow (A. chinensis Planch.) and green (A. deliciosa (A. Chev.) Liang & Ferguson) kiwifruits were inoculated with Pseudomonas syringae pv. actinidiae(PSA), an important and emerging threat of kiwi plants in Italy, 24 hours after soil chitosan treatment and maintained in a quarantine greenhouse. The SAR’s onset was determined 2 weeks after the bacterial inoculation with the detection of plant response to the infection by biochemical analyses. In particular, to evaluate the link between chitosan and SAR, the activities of enzymes involved in biotic stress response were determined, i.e. antioxidant enzymes guaiacol peroxidase (G-POD) and ascorbate peroxidase (APX), and those of phenolic compounds pathway (phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO)).
According to the results, both species treated with chitosan counteracted the pathogen attack in a similar way. In fact, after elicitor application the activities of antioxidant enzymes (G-POD and APX) and of enzymes involved in strenghtening plant defence barriers (PAL and PPO) were increased in both species. Moreover, the higher phenol amounts observed after the treatement further confirmed chitosan’s role in eliciting plant responses against the pathogen.
Further tests on chitosan’s potential as an elicitor of SAR in kiwifruit plants are in progress. A rapid method to evaluate its effect has been adopted. Following a screening of possible SAR molecular markers, two members of Pathogenesis Related Protein families (PR1 and PR5) were chosen and two primers pairs were designed for measuring PR gene expression. A quantitative method such as qRT-PCR will be used to quantify the elicitation induced by chitosan at the molecular level during different developmental stages of kiwi plants.
This study has shown the reliability of chitosan treatment in eliciting plant defence response and its potential in the protection against PSA. Thus chitosan might be considered a sustainable and eco-friendly alternative to the traditional and hazardous pesticides for kiwi pest management, in order to reduce the number of chemical treatments
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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