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Studio di soluzioni sostenibili per la protezione della vite da Plasmopara viticola e Botrytis cinerea
No full textIn agricoltura, la ricerca di alternative sostenibili per il controllo dei microorganismi fitopatogeni rientra attualmente tra i principali obiettivi delle politiche internazionali. Questo progetto si è focalizzato in particolare su due importanti patogeni della vite: l’oomicete Plasmopara viticola, agente eziologico della peronospora della vite, e il fungo Botrytis cinerea, che causa il marciume dei grappoli.
Nella prima parte del progetto, è stata studiata e caratterizzata, sia in vitro che in campo, l’attività antiperonosporica di un nuovo fitocomplesso ottenuto da colture cellulari di Salvia officinalis.
Il fitocomplesso inibisce la sporulazione del patogeno su dischetti di foglia inoculati con sporangi di P. viticola. Un buon livello di inibizione si ottiene anche quando l’inoculo viene ritardato di 5 giorni. Le analisi al microscopio ottico indicano che sporangi, cistospore e zoospore sono tutte danneggiate da trattamento, con livelli crescenti di suscettibilità.
Durante la prova di campo, realizzata nella primavera-estate del 2021, si è osservato un certo livello di efficacia nel controllo della malattia da parte del fitocomplesso, tuttavia la resa non è risultata significativamente diversa da quella delle piante di controllo. La quantificazione degli zuccheri e degli acidi organici negli acini ha evidenziato un ritardo nella maturazione dei frutti di piante trattate con il fitocomplesso. Visti i risultati promettenti delle sperimentazioni e visto che il processo produttivo altamente standardizzato permette di ottenere un estratto dalla composizione costante, si può affermare che ci sono le potenzialità per sviluppare un prodotto fitosanitario protettivo a partire dal fitocomplesso oggetto di studio.
Nella seconda parte del progetto è stato studiato l’effetto del trattamento combinato di eugenolo, principale componente dell’olio essenziale di chiodi di garofano, e pep4R, un peptide antimicrobico, su Botrytis cinerea. I test di inibizione della crescita in vitro hanno permesso di rilevare una incompatibilità tra i due principi attivi, che è stata confermata dall’analisi trascrittomica. Più specificamente, l’effetto del pep4R era mascherato dall’eugenolo, probabilmente a causa di un’interferenza di quest’ultimo con l’abilità del peptide di formare canali transmembrana. L’analisi RNA-seq ha anche fornito un quadro dettagliato della risposta trascrizionale del patogeno a dosi subletali di eugenolo dopo 1h o 3h di trattamento. Dopo 1 h è stata osservata l’inibizione della sintesi dell’ergosterolo, che è coerente con il meccanismo d’azione già proposto per l’eugenolo. Come risultato della condizione di stress indotta dall’eugenolo, è stata anche osservata la soppressione di processi biologici di base (es. divisione cellulare) e la contestuale sovraregolazione di trasportatori per la resistenza agli xenobiotici, di enzimi putativi per la degradazione dell’eugenolo e del sistema di detossificazione dai ROS. A 3 h, mentre la maggior parte delle vie metaboliche precedentemente alterate erano tornate a livelli trascrizionali normali, si è tuttavia osservata una significativa sovraregolazione dei fattori di virulenza, specialmente dei geni per la sintesi della tossina botrydial. Ciò suggerisce che il patogeno non solo è riuscito ad adattarsi alla presenza di eugenolo nel mezzo, ma ha anche avviato una risposta di difesa mediante la produzione di fattori di virulenza, quali tossine e proteine che inducono la morte cellulare nella pianta ospite. Questi risultati ampliano la nostra conoscenza riguardo la risposta di un fungo patogeno ad un trattamento fungicida e la sua capacità di adattamento.The need for alternative active compounds and strategies to control plant pathogens in the field is ever more urgent. This project focuses on two relevant grapevine pathogens, namely the oomycete Plasmopara viticola, causal agent of grapevine downy mildew, and the fungus Botrytis cinerea, causing grape bunch rot.
In the first part of the project, a new phytocomplex, obtained from Salvia officinalis elicited cell cultures, was tested against P. viticola, and its effect was characterized both in vitro and in the field. Sporulation on grape vine leaf discs was inhibited when discs were treated with the phytocomplex and inoculated with P. viticola sporangia. A good inhibition level was maintained also when inoculation was delayed for five days. Microscopic observations indicated that sporangia, cystospores and zoospores were all negatively affected by the treatment, with increasing levels of susceptibility. During the field trial, performed in spring-summer 2021, a partial disease control was observed in the plants treated with the phytocomplex, but this did not result in a higher yield compared to the untreated control. Sugars and organic acids quantification highlighted a ripening delay of grapes harvested from plants treated with the phytocomplex. These promising results and the consistent composition of the phytocomplex guaranteed by the innovative production process, all support the idea that it would be worthwhile to further develop the potential of this product for crop protection purposes.
In the second part of this project, the effect of a combined treatment was studied to understand the potential of clove essential oil major component, eugenol, and the antimicrobial peptide pep4R, used together against B. cinerea. The growth inhibition assays revealed an incompatibility between the two active compounds, which was confirmed by whole transcriptome analysis. More specifically, the effect of pep4R was elided by eugenol, which probably interferes with the ability of the peptide to form channels in the membranes. RNA-seq also provided a detailed snapshot of the pathogen transcriptomic response to sublethal concentrations of eugenol after 1 and 3 h treatment. After 1 h, the inhibition of ergosterol biosynthesis was recorded, which is consistent with the proposed mode of action of eugenol. As a result of the stress condition triggered by eugenol, we observed the downregulation of basic biological processes (e.g. cell division) and the concurrent upregulation of multidrug resistance transporters, putative eugenol degrading enzymes and ROS detoxification system, suggesting the activation of an oxidative stress in the fungal cells. At 3 h, while most dysregulated pathways had returned to normal or less extreme expression levels, we observed a remarkable upregulation of virulence factors, especially of botrydial synthesis genes. This indicates that the pathogen was able not only to adapt to eugenol in the culture medium, but also to counterattack with the production of toxins and cell death inducing proteins. Overall, these results expand our knowledge regarding the response of a fungal pathogen to an antifungal treatment and its adaptation abilities
A Phytocomplex Obtained from Salvia officinalis by Cell Culture Technology Effectively Controls the Grapevine Downy Mildew Pathogen Plasmopara viticola
Full text linkThe negative impact of using conventional fungicides in plant disease protection has increased the interest in safer alternatives such as plant secondary metabolites, generally having a better toxicological profile. However, cultivation conditions and plant material strongly affect the quality and quantity of secondary metabolites obtained from field grown plants, limiting the standardization needed for industrial production. Plant cell culture technology can provide highly homogeneous biomasses with specific chemical characteristics. A phytocomplex with high rosmarinic acid content (10.12% w/w) was obtained from a selected cell line of Salvia officinalis and was tested against the grapevine downy mildew pathogen, Plasmopara viticola. Grapevine leaf discs were sprayed with the phytocomplex at 5 g/L and then inoculated with P. viticola sporangia. Sporulation level on each disc was assessed after 7 days with an image processing software. The phytocomplex reduced by 95% the sporulation le..
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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