This open access book in the field of plant pest detection shows a constant demand in development and improvement of fast and reliable detection tools, especially for high-priority pests. This open ...access book describes and summarizes the whole process of the organization of test performance study (TPS) for these tools. The outcome of TPS, obtained through the evaluation of the performance of one or more diagnostic tests by several laboratories on defined samples, is the finding of the best performing test/s for particular pest and for specific uses. Nowadays the intensification of worldwide trade and associated controls increases the need for quality assurance accreditation and harmonization of laboratories practices. Therefore, such studies are very important, but, non-existent. Considering those facts, our goal was to develop guidelines, by using the data and experiences of involved partners, for further TPS in the field of plant health. Developed guidelines could be easily transferable to other microbiology fields.
Viruses cause a big fraction of economically important diseases in major crops, including tomato. In the past decade (2011–2020), many emerging or re-emerging tomato-infecting viruses were reported ...worldwide. In this period, 45 novel viral species were identified in tomato, 14 of which were discovered using high-throughput sequencing (HTS). In this review, we first discuss the role of HTS in these discoveries and its general impact on tomato virome research. We observed that the rate of tomato virus discovery is accelerating in the past few years due to the use of HTS. However, the extent of the post-discovery characterization of viruses is lagging behind and is greater for economically devastating viruses, such as the recently emerged tomato brown rugose fruit virus. Moreover, many known viruses still cause significant economic damages to tomato production. The review of databases and literature revealed at least 312 virus, satellite virus, or viroid species (in 22 families and 39 genera) associated with tomato, which is likely the highest number recorded for any plant. Among those, here, we summarize the current knowledge on the biology, global distribution, and epidemiology of the most important species. Increasing knowledge on tomato virome and employment of HTS to also study viromes of surrounding wild plants and environmental samples are bringing new insights into the understanding of epidemiology and ecology of tomato-infecting viruses and can, in the future, facilitate virus disease forecasting and prevention of virus disease outbreaks in tomato.
In agroecosystems, viruses are well known to influence crop health and some cause phytosanitary and economic problems, but their diversity in non-crop plants and role outside the disease perspective ...is less known. Extensive virome explorations that include both crop and diverse weed plants are therefore needed to better understand roles of viruses in agroecosystems. Such unbiased exploration is available through viromics, which could generate biological and ecological insights from immense high-throughput sequencing (HTS) data.
Here, we implemented HTS-based viromics to explore viral diversity in tomatoes and weeds in farming areas at a nation-wide scale. We detected 125 viruses, including 79 novel species, wherein 65 were found exclusively in weeds. This spanned 21 higher-level plant virus taxa dominated by Potyviridae, Rhabdoviridae, and Tombusviridae, and four non-plant virus families. We detected viruses of non-plant hosts and viroid-like sequences and demonstrated infectivity of a novel tobamovirus in plants of Solanaceae family. Diversities of predominant tomato viruses were variable, in some cases, comparable to that of global isolates of the same species. We phylogenetically classified novel viruses and showed links between a subgroup of phylogenetically related rhabdoviruses to their taxonomically related host plants. Ten classified viruses detected in tomatoes were also detected in weeds, which might indicate possible role of weeds as their reservoirs and that these viruses could be exchanged between the two compartments.
We showed that even in relatively well studied agroecosystems, such as tomato farms, a large part of very diverse plant viromes can still be unknown and is mostly present in understudied non-crop plants. The overlapping presence of viruses in tomatoes and weeds implicate possible presence of virus reservoir and possible exchange between the weed and crop compartments, which may influence weed management decisions. The observed variability and widespread presence of predominant tomato viruses and the infectivity of a novel tobamovirus in solanaceous plants, provided foundation for further investigation of virus disease dynamics and their effect on tomato health. The extensive insights we generated from such in-depth agroecosystem virome exploration will be valuable in anticipating possible emergences of plant virus diseases and would serve as baseline for further post-discovery characterization studies. Video Abstract.
The distribution and frequency of potato leaf roll virus in the four most important potato growing regions in Serbia were studied during the seven years (2012–18). One hundred randomly collected ...potato tubers were sampled from each seed lot. The young leaves that developed in three weeks were sampled and tested to record infection rate. The presence of potato leaf roll virus was detected by double-antibody sandwich enzyme-linked immunosorbent assay and disease incidence was calculated using standard formula. The obtained result showed that the highest prevalence of potato leaf roll virus was detected from seed potato samples originated from the Raški region during 2018 (20.7%), while in the Moravički region, only 2.3–11.1% of the potato leaf roll virus was detected every year. The average annual potato leaf roll virus infection was the highest in 2012 (8.4%) and 2018 (8.0%). For further confirmation of potato leaf roll virus infection, reverse transcription (RT)-PCR was performed using specific primers PLRVCPv
Eco
RI /PLRVCPc
Nco
I, designed to amplify a 650 bp fragment of the full-length coat protein gene. The PCR products derived from 26 isolates were directly sequenced using the same primer pair as in RT-PCR. The coat protein sequence analysis revealed that the Serbian potato leaf roll virus isolates showed very low nucleotide diversity (95.9–100%). They shared the highest nt identities of 98.08–99.36% with the sequences of potato leaf roll virus isolates deposited in the GenBank from other parts of the world. Phylogenetic analysis and the haplotype network of the coat protein gene sequences showed that the Serbian potato leaf roll virus isolates could be classified in two different groups indicating two possible introductions of the virus to Serbia. The results of this study confirmed the importance of potato leaf roll virus in seed potato production in Serbia. Additionally, this research highlights the need for a continuous monitoring of the potato seeds produced in Serbia as well as imported seeds for the presence of potato leaf roll virus.
A four-year survey (2012–2015) was carried out to examine the genetic diversity of cucumber mosaic virus (CMV) isolates infecting tomato, as well as the presence and diversity of their satellite RNAs ...(satRNAs), collecting a total of 226 samples throughout the most important growing regions in Serbia. Besides CMV-like symptoms, the collected samples also exhibited more severe symptoms, such as systemic necrosis of leaves, branches and stems, accompanied by fruit malformation and necrosis. In a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), the presence of CMV was detected in approximately one quarter of the tested samples. Identification of CMV was confirmed by conventional reverse transcription-polymerase chain reaction (RT-PCR) and sequencing of the coat protein (CP) gene of a group of 11 selected Serbian CMV isolates. Phylogenetic analysis of the CMV CP sequences of these selected isolates revealed their heterogeneity, as they fell into two different subgroups, IA and II. An additional RT-PCR analysis of CMV positive isolates using satellite RNAs specific primers detected the presence of satRNAs in eight samples. Sequence and phylogenetic analyses showed that Serbian CMV satRNAs variants were very heterogeneous, belonging to necrogenic and non-necrogenic variants. Necrogenic variants were divided into two groups, B and B1, containing a characteristic ‘necrogenic consensus’ sequence at the 3′ end of the RNA. A necrotic phenotype co-determined by satRNAs was expressed in inoculated tomato plants.
Tomato brown rugose fruit virus (ToBRFV) has recently emerged as a major disease of tomatoes and peppers. ToBRFV is a seed- and contact-transmitted virus. In Slovenia, ToBRFV RNA was detected in ...samples of wastewater, river, and water used to irrigate plants. Even though the source of detected RNA could not be clearly established, this raised the question of the significance of the detection of ToBRFV in water samples and experimental studies were performed to address this question. The data presented here confirm that the release of virus particles from the roots of infected plants is a source of infectious ToBRFV particles in water and that the virus can remain infective up to four weeks in water stored at room temperature, while its RNA can be detected for much longer. These data also indicate that irrigation with ToBRFV-contaminated water can lead to plant infection. In addition, it has been shown that ToBRFV circulated in drain water in commercial tomato greenhouses from other European countries and that an outbreak of ToBRFV can be detected by regular monitoring of drain water. A simple method for concentrating ToBRFV from water samples and a comparison of the sensitivity of different methods, including the determination of the highest ToBRFV dilution still capable of infecting test plants, were also investigated. The results of our studies fill the knowledge gaps in the epidemiology and diagnosis of ToBRFV, by studying the role of water-mediated transmission, and provide a reliable risk assessment to identify critical points for monitoring and control.
Flavescence dorée (FD) phytoplasma from 16SrV-C and -D subgroups cause severe damage to grapevines throughout Europe. This phytoplasma is transmitted from grapevine to grapevine by the sap-sucking ...leafhopper
. European black alder and clematis serve as perennial plant reservoirs for 16SrV-C phytoplasma strains, and their host range has recently been extended to hazelnuts. In Slovenia, hazelnut orchards are declining due to 16SrV phytoplasma infections, where large populations of the non-autochthonous leafhopper
have been observed. To better characterise the phytoplasma-induced decline of hazelnut and possible transmission fluxes between these orchards and grapevine, genetic diversity of 16SrV phytoplasmas in grapevine, hazelnut and leafhoppers was monitored from 2017 to 2022. The nucleotide sequence analysis was based on the
gene. The most prevalent
genotype in grapevine in all wine-growing regions of Slovenia was M54, which accounted for 84% of the 176 grapevines tested. Besides M54, other epidemic genotypes with lower frequency were M38 (6%), M51 (3%), M50 (2%) and M122 (1%). M38, M50 and M122 were also detected in infected cultivated hazelnuts and in specimens of
leafhopper caught in declining hazelnut orchards. It suggests that this polyphagous vector could be responsible for phytoplasma infection in hazelnut orchards and possibly for some phytoplasma exchanges between hazelnuts and grapevine. We hereby describe new genotypes: M158 in grapevine as well as four never reported genotypes M159 to M162 in hazelnut. Of these four genotypes in hazelnut, one (M160) was also detected in
. Analysis of additional genes of the new genotypes allowed us to assign them to the VmpA-III cluster, which corresponds to the 16SrV-C strains previously shown to be compatible with
transmission.
Plant viruses pose a significant threat to agriculture. Several are stable outside their hosts, can enter water bodies and remain infective for prolonged periods of time. Even though the quality of ...irrigation water is of increasing importance in the context of plant health, the presence of plant viruses in irrigation waters is understudied. In this study, we conducted a large-scale high-throughput sequencing (HTS)-based virome analysis of irrigation and surface water sources to obtain complete information about the abundance and diversity of plant viruses in such waters. We detected nucleic acids of plant viruses from 20 families, discovered several novel plant viruses from economically important taxa, like Tobamovirus and observed the influence of the water source on the present virome. By comparing viromes of water and surrounding plants, we observed presence of plant viruses in both compartments, especially in cases of large-scale outbreaks, such as that of tomato mosaic virus. Moreover, we demonstrated that water virome data can extensively inform us about the distribution and diversity of plant viruses for which only limited information is available from plants. Overall, the results of the study provided extensive insights into the virome of irrigation waters from the perspective of plant health. It also suggested that an HTS-based water virome surveillance system could be used to detect potential plant disease outbreaks and to survey the distribution and diversity of plant viruses in the ecosystem.
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