project - Research and innovation

VIRTIGATION - Emerging viral diseases in tomatoes and cucurbits: Implementation of mitigation strategies for durable disease management

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Ongoing | 2021 - 2025 Belgium
Ongoing | 2021 - 2025 Belgium

Contexte

ToLCNDV (genus Begomovirus) was reported in Spain in 2012 and subsequently in Italy, Morocco and Tunisia. ToLCNDV is transmitted by the whitefly Bemisia tabaci, which makes its control very difficult and is prompting producers to use pesticides. In the recent years, severe epidemic outbreaks of the disease were associated with ToLCNDV and caused serious economic losses to greenhouse and openfield cucurbit crops, as infection can lead to complete crop loss. The rapid spread of ToLCNDV in the Mediterranean Basin represents a threat for horticultural production and calls for the implementation of phytosanitary and IPM measures including biological control of vectors and genetic resistance strategies. ToLCNDV was added to the EPPO Alert List in 2017.
The new tobamovirus ToBRFV is currently posing a huge threat to tomato and pepper crops worldwide as it breaks natural Tm-based resistances bred in commercial tomato varieties, especially under warm conditions. After the first identification in Israel and in Jordan in 2014, ToBRFV has been reported in the recent years in Germany, Italy, the UK, Greece, the Netherlands, Spain, Turkey and Italy. In 2019 the virus was added to the EPPO alert list and emergency measures are currently in force in the EU. Tobamoviruses are seed borne viruses. Infected seeds and plant debris may constitute a primary infection via soil and irrigation water contamination. The primary mode for tobamovirus contamination is mediated by mechanical plant manipulations and root injury. Beneficial insects (i.e. pollinators) may also participate in virus transmission. Climate change, trade, agrosystems and other aforementioned factors contribute to arising global virus threats to crop production.

Objectives

VIRTIGATION aims at developing rapid and lasting solutions to emerging viral diseases caused by begomoviruses (whitefly-transmitted) and tobamoviruses (mechanically transmitted) on cucurbits and tomato in Northern Europe and the Mediterranean Basin, and increasing knowledge to better control and manage the viral diseases. It is structured in 6 objectives :
1. Knowledge sharing and engagement of stakeholders in research activities
2. Develop robust diagnostic tests, quarantine measures and identify ecological factors driving disease outbreaks
3. Understand plant-virus(es)-vector interactions
4. Develop IPM solutions 
5. Pyramidize natural resistance 
6. Train the value chain 

Activities

VIRTIGATION's objectives will build on 1) detailed study of virus biology and transmission under climate change conditions; 2) development of classical solutions (IPM and natural resistance) to control viral diseases with two distinct modes of transmission; 3) testing novel approaches (biopesticides, biological control, cross-protection) to mitigate viral diseases and to reduce pesticide usage.

In order to take into account the diversity of vegetable cropping systems and viral diseases, focus groups involving extension services, commercial companies and growers will help co-designing research activities and mitigation strategies from the onset of the project.

Additional comments

The specific objectives of VIRTIGATION's multi-actor approach are to:
• Create common tools and guidelines for the implementation of the multi-actor approach
• Establish the VIRTIGATION network at various governance levels  in the project’s 11 focus countries
• Use the project’s national knowledge brokers (NKBs) to define a joint approach for all parts of the VIRTIGATION network to harmonize protocols and methods used for data gathering and delivering co-creation
• Coordinate events, joint activities and prepare Practice Abstracts for EIP-AGRI to stimulate co-design and exchange of knowledge between the VIRTIGATION consortium and the stakeholders of the VIRTIGATION network;                                                            The project’s NKBs have already identified an initial set of relevant stakeholders in all of the project’s 11 focus countries in Europe (Belgium, Netherlands, UK, France, Italy, Luxembourg, Spain, Germany) and across the globe (Israel, Morocco, India) to be included in the VIRTIGATION network. The NKBs have also defined the roles and expected involvement of the stakeholders in the network, to gather effective and continuous information to feed into the project’s scientific research.
VIRTIGATION’s multi-actor approach is based on established stakeholder relations of the project’s consortium. With this in mind, VIRTIGATION seeks to promote the active participation of the VIRTIGATION network members (e.g. farmers, growers, agro-industry, universities, research technology organizations and agricultural extension services) to co-design, refine and tailor its research to the needs of its stakeholders, to maximize the added-value of VIRTIGATION’s generated results for its stakeholders. 

Additional information

VIRTIGATION engages in a bottom-up, multi-actor approach to tailor its innovative solutions to the needs of the agriculture and horticulture sectors. Since the project’s aim is to have a durable impact on the entire tomato and cucurbit value chain, close collaborations with key actors and stakeholders such as farmers, growers, public research centers and seed and plant protection industries are essential. By linking producers directly with consumers, VIRTIGATION will create a multi-stakeholder network on emerging plant virus detection and knowledge exchange. Co-creation and co-design is at the heart of VIRTIGATION’s research activities, where it will not only directly use the inputs provided by the stakeholders of the VIRTIGATION network, but also train them in applying innovative bio-based remedies through common tools and guidelines. The ambition of the VIRTIGATION network is on the one hand to collate national know-how through the coordination efforts of National Knowledge Brokers, and on the other to ensure global exchange between actors in Europe, Israel, Morocco and India, in order to jointly combat the emerging viral diseases affecting tomatoes and cucurbits. 

Project details
Main funding source
Horizon 2020 (EU Research and Innovation Programme)
Horizon Project Type
Multi-actor project
Emplacement
Main geographical location
Arr. Leuven

EUR 7,358,170.00

Total budget

Total contributions including EU funding.

16 Practice Abstracts

In a collaborative study performed by researchers at CRAG (Centre for Research in Agrigenomics, CSIC-IRTA-UAB-UB) in Barcelona and at IHSM (Institute for Subtropical and Mediterranean Horticulture "La Mayora", CSIC-UMA) in Málaga, we have analyzed the genes of tomato plants that were activated or repressed after 2, 7, and 14 days after infection with the Tomato chlorosis crinivirus, ToCV. The results showed an early activation of response mechanisms to infestation by the insect vector, in our case the viruliferous whiteflies used for the inoculation, and later on, once the virus was established, lead to the activation of antiviral defense systems. To confirm these results, two genes previously related to plant immunity, named Hsp90 and Sgt1, were selected from the list of genes with altered expression, and their importance was verified through specific experiments in which their expression was silenced. To do so, the virus accumulations were quantified after artificially reducing the expression levels of the selected genes, finding that in parallel the plants' susceptibility to the virus infection was increased. These results, which served to identify components of the cellular machinery responding to virosis, will help us to design control strategies that utilize the enhancement of the plants' natural defenses to fight against viruses.
 

This summary refers to a collaboration of researchers at CRAG (Centre for Research in Agrigenomics, CSIC-IRTA-UAB-UB) in Barcelona, and colleagues at IHSM (Institute for subtropical and Mediterranean Horticulture "La Mayora", CSIC-UMA) in Malaga, and  intends to provide descriptive procedures for studying in laboratory conditions the transmission of plant pathogenic viruses by insect vectors, coonsidering the most frequent and important vector organisms like aphids and whiteflies.  Indeed, many species of plant viruses are naturally disseminated through specific transmission by insect vectors, mainly phytophagous homopterans including aphids and whiteflies. For a successful transmission, and depending on the vector specificity and the mode of transmission, different durations of the periods for acquisition, retention, and inoculation are required. Therefore, the experimental setup to perform controlled transmission experiments under laboratory conditions involves handling the vector organisms and managing the times for the different steps of the process to optimize and standardize the results. The  basic procedures that can be applied to vector-mediated transmission experiments are described, giving examples for selected viruses and different host plants.
 

"""VIRTIGATION is a multi-actor project on a mission to protect tomatoes and cucurbits in Northern Europe and the Mediterranean Basin. Together with partners from key EU neighbouring areas – Morocco, Israel and India – the VIRTIGATION project aims to develop a set of bio-based solutions to safeguard tomatoes and cucurbits from emerging viral diseases.
Specifically, VIRTIGATION addresses emerging viral diseases caused by the begomovirus ToLCNDV (Tomato leaf curl New Delhi Virus, transmitted by whiteflies) and the tobamovirus ToBRFV (Tomato brown rugose fruit virus, mechanically transmitted). In particular practice-relevant measures will be developed to protect these plants."""
 

Bemisia tabaci (Hemiptera: Aleyrodidae) is a significant pest worldwide, causing damage to plants both directly and indirectly by transmitting numerous economically important viruses. The Tomato Leaf Curl New Delhi Virus (ToLCNDV), transmitted by whiteflies from the Bemisia tabaci complex, spread from Southeast Asia to the Mediterranean region in the early 2000s. ToLCNDV affects cucurbits and has caused significant economic losses in Europe, particularly in Greece, Italy, Spain, Portugal, and recently in France. Climate change is expected to exacerbate the spread of B. tabaci and its associated diseases. To better understand how climate change will affect the epidemiology of ToLCNDV in cucurbits, LIST researchers are testing how changes in temperature, humidity, and CO2 concentration in climatic chambers will affect the acquisition and inoculation of ToLCNDV in B. tabaci, as well as the gene expression of target genes in the whitefly vector. The experiments aim to shed light on an unexplored topic and help address future challenges in plant protection.
 

The project VIRTIGATION, funded by the European Union under the Horizon 2020 programme, involves 25 partners from 12 different countries, and aims to develop solutions for the control of emerging viruses on cucurbits and tomatoes caused by begomoviruses and tobamoviruses (the first ones transmitted by insects). Main entomological objectives of the project are to: i) understand plant-virus-vector interactions; ii) identify ecological factors that favour outbreaks of infections; iii) investigate biology of vector insects and their virus transmission efficiency under climate change conditions; iv) enhance and optimize natural resistance, especially for lower attractiveness of plants to vector insects; v) develop solutions for the integrated control of the viruses and their vectors. Within this project, the University of Catania (Department of Agriculture, Food and Environment – Di3A) will have to: a) contribute to a survey in various partner countries on methods used for whitefly control, especially Bemisia tabaci; b) coordinate field trials to evaluate the efficacy of new plant extracts with insecticidal action, also analysing their secondary effects on natural enemies and pollinators; c) carry out field trials with the most promising accessions for their resistance to B. tabaci MED; d) evaluate the combination of different approaches for whitefly control. 
 

Whiteflies (Hemiptera: Aleyrodidae) are critical pests attacking many cultivated plants in almost all areas of the world. Among them, Bemisia tabaci (Gennadius) is a global pest that causes significant losses to a wide variety of crops by affecting plants development. To control B. tabaci infestations, the release of natural enemies has become increasingly important as an ecologically safe and effective biological control method and, among predators used, the mirid bug Macrolophus pygmaeus (Rambur) plays a primary role. Anyway, due to its zoophytophagous habits, a wrong application rate of this predator can also make this beneficial a threat to the plants; and this is why a better understanding is needed of the role that M. pygmaeus plays on crops, evaluated in a holistic way. To this aim, and in order to deepen knowledge on the impact that whiteflies alone or combined with M. pygmaeus may have on vegetable solanaceous crops (with special emphasis to tomato and eggplant), the main morphological (total height, dry weights, leaf area) and physiological (photosynthetic performance, indirect chlorophyll content) parameters of the plants were analysed in different conditions (healthy plants, or infested by the pest, or with pest and predator together). At the experimental conditions and the insect densities adopted, results show a variable susceptibility by different plant species to B. tabaci and a significant reduction induced by M. pygmaeus in negative effects caused by the pest on morpho-physiological traits of the plants.
 

Tomato leaf curl New Delhi virus (ToLCNDV) is now emerging in the Mediterranean Basin, starting from Spain in 2012. It has been observed for the first time in France in 2020 in  Gard and Bouches-du-Rhône. Mediterranean ToLCNDV is a bipartite begomovirus, causing leaf curl disease mainly in zucchini and others cucurbits, and genetically distinct from Asian (Indian)-ToLCNDV that has a broader host range. The cryptic species of whitefly Bemisia tabaci is the main insect vector of ToLCNDV while mechanical inoculation is also possible. Previous studies indicate that the Mediterranean clade represents a homogenous population, probably originating from a single introduction. We established a suitable protocol of inoculation and performed biological and molecular characterization of the French isolates in order to estimate their risks of emergence and their potential agronomic impact. Symptom observation of French ToLCNDV isolates on melon and zucchini showed two different types so-called “severe” and “recovery”. French ToLCNDV was found to be transmissible by Bemisia tabaci as expected but not by the greenhouse whitefly Trialeurodes vaporariorum. Host range analysis in experimental conditions suggest that Bryony and Tomato are susceptible to French and Spanish ToLCNDV and may constitute virus reservoirs, what should be taken into consideration for virus control. Our results expand the knowledge on this emerging virus and offer perspectives for shaping the future plant disease management.
 

ToBRFV is a newly emerged virus that causes severe losses in tomato production. Within five years, ToBRFV infections were reported in Asia, North America and Europe. ToBRFV belongs to tobamovirus genus, however all the available tomato resistant varieties used for tobamoviruses, such as TMV and ToMV, cannot halt infections caused by this new virus. The severity of this disease, its rapid spread, and the scarcity of resistant cultivars make this virus a global threat for tomato production. Our objective is to find ToBRFV resistance in wild Solanum accessions and introgress this trait into tomato cultivars reaching the first step for creating modern resistant tomato varieties. So far, we have screened 75 Solanum accessions from which two S. pennellii found resistant to ToBRFV. Segregation populations have been obtained from these two accession that is the first step for mapping the gene responsible for the resistance trait. The identification and introgression of the resistance gene are in progress.                                                                  
 

TECNOVA (TEC, Spain) and Landwirtschaftskammer Nordrhein-Westfalen (LNW, Germany) work together in the task “Optimization of eradication methods after tobamovirus outbreaks” of VIRTIGATION project. Both institutes are working on the validation of solarization and steaming methods to eradicate tobamoviruses in contaminated cocopeat bags by TMV (Tobacco mosaic virus). For solarization, TEC has used a transparent 37.5 µm think polyethylene plastic during 60 days (from September to November to try simulate the summer in other countries in Europe) with reordered temperatures between 15.2 to 46.2°C. LNW is testing two steaming protocols: (1) 90 °C during 20 min and (2) at 90 °C during 40 min. In order to test the success of both methods, the disinfected bags were used to growth new plants. In addition, it has tried to discern if the substrate must necessarily be free of crop residues or not. The results of the solarization have been very promising. All tomato plants grew up symptomless in solarized bags. Only in one of the six lines (temperature > 40°C during 10-13 days) TMV were detected by PCR. Moreover, in bags with infected material (roots and leaves), the maximum temperature was until 4°C higher than in bags with just substrate. Incorporate vegetal material helped to increase the number of days with high temperature (> 40°C), from 7-13 to 14-34 days in substrate bags without and with infected material, respectively. The steaming results are coming soon in the following moths. After steaming it has been detected: (i) plants in the non-steamed bags showed better fitness than the steamed variants; (ii) growth of mold fungi could be observed on the substrate and (iii) substrate bags must be used immediately and cannot be stored for a while.
 

Tomato brown rugose fruit virus (ToBRFV) poses a huge threat to commercial tomato cultivation worldwide. Due to its high persistence and easy mechanical transmission, ToBRFV is extremely hard to get rid of once it enters the greenhouse. Current management strategies therefore centre around preventive measures, such as improved hygiene, in an attempt to keep the virus out of the crop. Early detection of the virus can also play an important role. Our research shows that ToBRFV circulates in greenhouse water systems and can be detected in drain water samples before the plants start showing symptoms. We illustrate that drain water can be used to monitor ToBRFV outbreaks and thus can serve as an early warning system.
 

Today, pest management based on biological control is the most sustainable alternative to pesticide use. The whitefly Bemisia tabaci is one of the key pests negatively impacting yield and quality of vegetable crops; while the predator Macrolophus pygmaeus is one of the main natural enemies widely used for its control, although it can sometimes behave as a pest, causing damage to plants. In this study, the impact of M. pygmaeus as a plant feeder has been investigated, by analyzing the combined impact of the whitefly and the predator bug on potted eggplants under laboratory conditions. Results show no statistical differences between the heights of plants infested by the whitefly or by both insects compared with non infested control plants. However, indirect chlorophyll content, photosynthetic performance, leaf area, and shoot dry weight were all greatly reduced in plants infested only by B. tabaci, compared with those infested by both the pest and its predator or with noninfested control plants. Contrarily, root area and dry weight values were more reduced in plants exposed to both insects, compared to those infested only by the whitefly or to noninfested plants (the latter showing the highest values). These results show how M. pygmaeus can significantly reduce the damage caused by B. tabaci to host plants, although its effects on the belowground part of the plants remains unclear. Anyway, from a practical point of view and given the overall positive effect of the predator, both for its control of the whitefly and reduction of negative effects on crops, its release during the early stages of B. tabaci infestation in greenhouse environments is recommended. 
 

Invasive weeds cause significant crop yield and economic losses in agriculture. The highest indirect impact may be attributed to the role of invasive weeds as virus reservoirs within commercial growing areas. The new tobamovirus tomato brown rugose fruit virus (ToBRFV), first identified in the Middle East, overcame the Tm-22 resistance allele of cultivated tomato varieties and caused severe damage to crops. In this study, we determined the role of invasive weed species as potential hosts of ToBRFV and a mild strain of pepino mosaic virus (PepMV-IL). Of newly tested weed species, only the invasive species Solanum elaeagnifolium and S. rostratum were susceptible to ToBRFV infection. S. rostratum was also susceptible to PepMV-IL infection. No phenotype was observed on ToBRFV-infected S. elaeagnifolium grown in the wild or following ToBRFV inoculation. S. rostratum plants inoculated with ToBRFV contained a high ToBRFV titer compared to ToBRFV-infected S. elaeagnifolium plants. Mixed infection with ToBRFV and PepMV-IL of S. rostratum plants, as well as S. nigrum plants (a known host of ToBRFV and PepMV), displayed synergism between the two viruses, manifested by increasing PepMV-IL levels. Additionally, when inoculated with either ToBRFV or PepMV-IL, disease symptoms were apparent in S. rostratum plants and the symptoms were exacerbated upon mixed infections with both viruses. In a bioassay, ToBRFV-inoculated S. elaeagnifolium, S. rostratum and S. nigrum plants infected tomato plants harboring the Tm-22 resistant allele with ToBRFV. The distribution and abundance of these Solanaceae species increase the risks of virus transmission between species.
 

Background Counting of insects on plants is crucial in plant breeding for insect resistance, to determine infestation in the field, or for assessment of crop protection products. The traditional method of visually counting insect (larvae, eggs) using a microscope is time-consuming and requires expertise. For instance, whiteflies, a  common pest on various crops, can lay up to hundreds of eggs on a single leaf within a few days. An automated and rapid method for quantifying insect eggs can save time and human resources. Results Researchers created a tool called Eggsplorer, which automates the counting of whitefly eggs. Images of leaves with whitefly eggs were collected using a custom-built imaging system. These images were used to train  a deep learning model that can detect and count the eggs accurately.  The model was then integrated in a user-friendly web-based application. In testing, Eggsplorer achieved a counting accuracy of nearly 94% when compared to manual counts. It proved to be a reliable method for determining the resistance and susceptibility of different plants to whitefly infestation. Practical recommendation: Eggsplorer presents a new method for fast automatic determination of insects eggs on plants, that is easily accessible for users in a web-based application. Eggsplorer could be integrated into mobile phone platforms allowing users to collect data on the go and receive real-time advice on pest infestation. Furthermore, this innovation can be further developed to analyze not only eggs but other developmental stages of other insects on different plants.
 

This review looks at the group of tobamoviruses to which tomato brown rugose fruit virus belongs. Some tobamoviruses cause latent infection in their hosts, which means that no obvious symptoms are visible. This has implicitations for diagnostics as multiple infections with latent and non-latent viruses may only focus on the symptom-inducing viruses. Furthermore, latent viruses may affect symptomology or replication of co-infecting viruses which may lead to more severe symptoms on host plants.
 

Begomoviruses constitute an extremely successful group of emerging plant viruses transmitted by whiteflies of the Bemisia tabaci complex. Hosts include important vegetable, root, and fiber crops grown in the tropics and subtropics. Factors contributing to the ever-increasing diversity and success of begomoviruses include their predisposition to recombine their genomes, interaction with DNA satellites recruited throughout their evolution, presence of wild plants as a virus reservoir and a source of speciation, and extreme polyphagia and continuous movement of the insect vectors to temperate regions. These features as well as some controversial issues (replication in the insect vector, putative seed transmission, transmission by insects other than B. tabaci, and expansion of the host range to monocotyledonous plants) will be analyzed in this review.
 

Begomoviruses constitute a successful group of emerging plant viruses threatening vegetable, root and fiber crops worldwide that are transmitted in nature by whiteflies of the Bemisia tabaci complex. Tomato leaf curl New Delhi virus is a paradigmatic example of a begomovirus that has recently emerged in Mediterranean countries after movement from its original location in the Indian subcontinent. The Mediterranean isolates of this virus belong to a novel strain, named “Spain strain”, which infects zucchini and other cucurbits but is poorly adapted to tomato. This work aimed to clarify some aspects of the whitefly transmission of tomato leaf curl New Delhi virus. It was shown that contrary to a recent study reporting the transmission of an Indian isolate of the virus by the greenhouse whitefly (Trialeurodes vaporariorum), the Mediterranean isolate is not transmitted by this insect. In addition, the most prevalent Bemisia tabaci species, Mediterranean, is not an efficient vector of this begomovirus between zucchini plants and the wild cucurbit Ecballium elaterium. These results suggest that this wild plant, although frequently infected, may not play a relevant role as a reservoir in the epidemiology of the disease caused by tomato leaf curl New Delhi virus Spain strain.
 

Contacts

Project coordinator

  • , KU Leuven, Coordinator

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Project partners

  • DCM CORP

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  • TECNOVA

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  • LIST

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  • NRI-University of Greenwich

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  • CSIC

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  • CRAG

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  • UNICT

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  • WU

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  • WR

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  • INRAE

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  • EMWEB

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  • Volcani Center

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  • PCH

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  • APREL

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  • JKI

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  • Syngenta France

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  • Scientia Terrae

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  • HVH2

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  • AGAPA

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  • LNW

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  • RTDS

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  • DCM CORP

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