INIBITORI DELLA BIOSINTESI DELLE PURINE PER LA TERAPIA ANTIVIRALE NEI VEGETALI: NUOVE MOLECOLE, STRATEGIE DI POTENZIAMENTO E MECCANISMO DI AZIONE

I virus rappresentano, per le colture agrarie, un fattore di rischio di primo piano. E’ indubbio che la più efficace strategia da attuare per la difesa di una coltura sia, per la bontà dei risultati e per i costi da sostenere, la prevenzione. Ma se l’esclusione o l’ultima ratio dell’eradicazione rappresentano necessità recepite anche da capitoli legislativi nazionali ed internazionali, le problematiche relative alle piante già infette non possono non trovare qualche risposta. Il recupero di individui di interesse per l’inserimento in programmi di miglioramento o selezione può confidare infatti su strategie di risanamento. Se la termoterapia rappresenta la tattica più perseguita, l’impiego di molecole chimiche di sintesi può rivelarsi efficace per i casi insoluti, grazie anche all’opportunità non secondaria di mutuare alcune armi della medicina. Ad oggi le molecole ascrivibili al gruppo degli inibitori dell’inosina monofosfato deidrogenasi (IMPDH) rappresentano, per la terapia nei vegetali, la risorsa più interessante, ma numerosi sono gli antivirali che, agendo anche su altri enzimi della via biosintetica delle purine entro la quale l’IMPDH agisce, presentano delle potenzialità da accertare. Nel presente lavoro, numerose sono le molecole inedite incluse in un programma di screening effettuato su plantule in vitro di tabacco infette da Cucumber mosaic virus (CMV) e Tobacco mosaic virus (TMV) e che hanno mostrato efficacia antivirale. Efficacia confermata anche per espianti di vite affetti da Grapevine leafroll-associated virus 3 (GLRaV 3), e che ha permesso di individuare come gruppo di sicuro interesse la classe molecolare delle tiopurine. Se mutuate dalla medicina umana sembrano essere numerose le molecole investigate nei vegetali, anche la strategia di potenziamento mediante la realizzazione di macrocostrutti sembra essere una via teoricamente percorribile. La sintesi di costrutti di acido micofenolico (MPA) a struttura poliammidoamminica non ha prodotto, però, i risultati sperati. Infatti, dalle evidenze sperimentali, sembra emergere la perdita parziale dell’efficacia antivirale dell’MPA sin dalle prime fasi di produzione dei costrutti, suggerendo l’opportunità di intraprendere questa strategia con differenti molecole meno sensibili all’alterazione strutturale derivante dalla produzione del costrutto. La chemioterapia nei vegetali, oltre a necessitare di nuovi strumenti o del potenziamento degli esistenti, abbisogna comunque di approfondimenti per quanto concerne i meccanismi di azione e sui fattori che ne influenzano i risultati. Mediante il test di screening è stata confermata la difficoltà ad eradicare TMV rispetto ad altri virus: questa peculiarità sembra essere intaccata solo da trattamenti che si prolungano nel tempo e che, seppur non eradicanti, mostrano qualche effetto sul virus. Il TMV sembra, ancora una volta, rappresentare un esemplare campo di prova per implementare le conoscenze virologiche: difatti la sua longevità in vitro, comparata a quella del CMV nel presente lavoro ed alla sua nota persistenza, sembra indicare nelle caratteristiche intrinseche del virus e nel suo rapporto con l’ospite un fattore chiave nella risposta chemioterapica, oltre che nell’efficacia del meccanismo di azione dell’antivirale. Meccanismo di azione che, per quanto concerne gli inibitori dell’IMPDH, è stato oggetto di studi specifici al fine di confermarne il ruolo anche nella terapia dei vegetali. I risultati sperimentali evidenziano come l’attività di un presunto inibitore esclusivo dell’IMPDH, quale il tiazofurin, sia parzialmente ridotta dalla somministrazione esogena di una molecola, la guanosina, la cui produzione dovrebbe essere drasticamente diminuita dall’azione dell’antivirale stesso. Seppure questa evidenza non sia conclusiva nell’indagine per la determinazione dell’effettivo meccanismo di azione di questa importante classe di antivirali, rappresenta un primo passo in accordo con quanto rilevato nella sperimentazione medica animale

Bibliometric Mapping of Research on Life Cycle Assessment of Olive Oil Supply Chain

The olive oil supply chain and even its individual stages have been extensively investigated through life cycle assessment (LCA) in recent decades. Most practices of the olive oil supply chain have been associated with negative environmental effects, such as soil degradation, carbon dioxide emissions, air and ground pollution, and depletion of groundwater. The current work aimed to perform a bibliometric analysis, through a science mapping approach, coupled with a review on the life cycle assessment (LCA) studies of the olive oil sector, with relevance to the environmental impacts of agricultural and industrial practices of this food sector. A total of 110 documents published in 2008–2021 were analyzed and discussed. More than 78% of documents were released from 2015. The main Scopus categories relating to the topic analyzed were environmental sciences (25%), energy (18%), and engineering (17%). The most productive countries were Italy, Spain, and Greece. The cluster analysis identified three main research topics related to the “agricultural phase”, “oil extraction”, and “waste management and by-product valorization”. Most of the recent publications focused on the application of LCA to evaluate the environmental impact of innovative agricultural practices, sustainable control of parasites and weeds, wastes, and by-products valorization within a circular economy

Plant Pathology and Information Technology: Opportunity for Management of Disease Outbreak and Applications in Regulation Frameworks

In many European rural areas, agriculture is not only an economic activity, but it is strictly linked to environmental and social characteristics of the area. Thus, sometimes, a pathogen can become a social threat, as in the case of Xylella fastidiosa and olive trees ( Olea europaea L.) in Salento. Fast and systemic response to threats represents the key to success in stopping pest invasions, and proves a great help in managing lots of data in a short time or coordinating large-scale monitoring coming from applying Information Technology tools. Regarding the field of applications, the advantages provided by new technologies are countless. However, is it the same in agriculture? Electronic identification tools can be applied for plant health management and certification. Treatments, agrochemical management or impact assessment may also be supported by dematerialization of data. Information Technology solution for urban forestry management or traceability of commodities belonging to "Food from Somewhere" regimes were analyzed and compared to protection from pests of a unique tree heritage such as olive trees in Salento

Chemical outbreak for tobacco mosaic virus control

Tobacco mosaic virus (TMV) represents a paradigm in virology, and its control may open the way to effective treatment against phytoviruses. However, the use of chemicals to eliminate the virus from infected plants is very difficult. In this state of the art survey we include trials on a) natural compounds derived from organisms, b) synthetic compounds and c) plant or microorganism extracts, from 2006 to 2015. Plants have been the main source of natural products for anti-TMV tests in the last ten years, and Nicotiana tabacum was the main focus of research, particularly between 2014-2015. Since 2012, there has been a great increase in publications (+45%) and identified compounds (+241%). Between 2012-2015, an average of 31 papers were published and 140 compounds were tested each year, compared to 9 papers and 26 compounds in 2006-2011. Unfortunately, there is little information on the action mechanisms of newly discovered or modified compounds. Cross references to the basic structure of compounds is provided in this review. This chemical outbreak this massive interest in chemical solutions to TMV could be due to the increasing availability of instruments for the analysis of organic compounds. Alternatively Another explanation could be that the chemistry advances in synthesis, which have provided countless drugs with potential benefits for TMV control, have overwhelmed overloaded the plant pathology screening needed to discriminate between compounds and to provide useful agrochemicals for farmers

Diseases Caused by Xylella fastidiosa in Prunus Genus: An Overview of the Research on an Increasingly Widespread Pathogen

Cultivated plants belonging to the genus Prunus are globally widespread and for some countries, are economically important crops; and they play a key role in the composition of a landscape. Xylella fastidiosa is a key threat to plant health, and several Prunus species are heavily stressed by this pathogen, such as almond, peach, and plum; many strain types of different subspecies can cause severe diseases. This review highlights different approaches to managing epidemic events related to X. fastidiosa in stone fruit plants. In fact, in most new European and Asian outbreaks, almond is the main and very common host and peach, plum, apricot, and cherry are widespread and profitable crops for the involved areas. Various diseases associated with stone fruit plants show different degrees of severity in relation to cultivar, although investigations are still limited. The development and selection of tolerant and resistant cultivars and the study of resistance mechanisms activated by the plant against X. fastidiosa infections seem to be the best way to find long-term solutions aimed at making affected areas recover. In addition, observations in orchards severely affected by the disease can be essential for collecting tolerant or resistant materials within the local germplasm. In areas where the bacterium is not yet present, a qualitative-quantitative study on entomofauna is also important for the timely identification of potential vectors and for developing effective control strategies

Effects of extracellular K+ on grapevine membrane potential as influenced by the antiviral mycophenolic acid. An electrophysiological study

Mycophenolic acid (MPA) is an effective antiviral drug in plants, and its action in modulating the activity of KATP channels is already known in animals. In the present work, an electrophysiological study was carried out to investigate MPA effects on plant K+ channels, through the measurement of trans-plasma membrane potential in samples of Vitis vinifera cv. Sangiovese treated with extracellular K+. Tests confirmed that the administration of MPA (in preincubated samples or in those maintained under chemical treatment) can reduce the membrane depolarization induced by K+. However, MPA-induced alteration in membrane potential was sensitive to the KATP channel opener diazoxide, as well to treatments with guanosine. This result confirms the effectiveness of MPA in influencing KATP channel activity as well as inhibiting activity of the inward-rectifier potassium ion channel which could be mediated by guanosine depletion induced by MPA

Recurrence Analysis of Vegetation Indices for Highlighting the Ecosystem Response to Drought Events: An Application to the Amazon Forest

Forests are important in sequestering CO2 and therefore play a significant role in climate change. However, the CO2 cycle is conditioned by drought events that alter the rate of photosynthesis, which is the principal physiological action of plants in transforming CO2 into biological energy. This study applied recurrence quantification analysis (RQA) to describe the evolution of photosynthesis-related indices to highlight disturbance alterations produced by the Atlantic Multidecadal Oscillation (AMO, years 2005 and 2010) and the El Niño-Southern Oscillation (ENSO, year 2015) in the Amazon forest. The analysis was carried out using Moderate Resolution Imaging Spectroradiometer (MODIS) images to build time series of the enhanced vegetation index (EVI), the normalized difference water index (NDWI), and the land surface temperature (LST) covering the period 2001–2018. The results did not show significant variations produced by AMO throughout the study area, while a disruption due to the global warming phase linked to the extreme ENSO event occurred, and the forest was able to recover. In addition, spatial differences in the response of the forest to the ENSO event were found. These findings show that the application of RQA to the time series of vegetation indices supports the evaluation of the forest ecosystem response to disruptive events. This approach provides information on the capacity of the forest to recover after a disruptive event and, therefore is useful to estimate the resilience of this particular ecosystem