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Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The genome of tomato spotted wilt virus (TSWV) can encode various proteins, including RdRp, NSm, NSs, Gc, Gn, and N. Existing research primarily focuses on plant (tomato and chili pepper) resistance to TSWV mediated by resistance genes (Sw-5b and Tsw). Furthermore, the inhibitory effects of agents on the TSWV N proteins have been investigated. TSWV proteins have the potential to be used as molecular targets for pharmaceutical agents, however, the mechanism of action between TSWV proteins and pharmaceutical agents has not been systematically and comprehensively reported. This study presents a detailed analysis of the three-dimensional structures of resolved TSWV proteins and predicts the structures of four unresolved TSWV proteins using AlphaFold2 modeling. It also summarizes the advancement and application of TSWV resistance genes and TSWV inhibitors in plant protection. The potential molecular mechanisms of ningnanmycin, moroxydine, and ribavirin on TSWV proteins were analyzed, along with their possible sites of action. The aim is to establish a theoretical foundation for subsequent comprehensive excavation and exploration of novel agents with anti-TSWV properties. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The incidence of thrips in the High Plains of Texas (USA) was investigated using sticky traps during the 2021 and 2022 seasons. Yellow sticky traps were placed in wheat fields and collected and replaced weekly and thrips were counted under a dissecting scope. Weekly wheat reflectance measurements were taken using a hyperspectral radiometer from which normalized difference vegetation index (NDVI) was calculated for each measurement. Temperature (degree day) and NDVI values were then related to weekly thrips incidence using regression. Thrips incidence curvilinearly increased over time during each of the two seasons and reached a maximum in the middle of June, after which it declined sharply. There was a strong positive relationship between degree days and thrips incidence until the incidence reached a maximum, whereas the incidence was negatively related to NDVI values. Analysis of the thrips changes over time progress with the two variables together showed that degree day has greater impact on thrips incidence than NDVI. However, the steep decline in thrips abundance after its peak in mid‐June suggests that senesced wheat fields with NDVI values near zero are not significant sources of thrips, signifying the importance of wheat growth stages in the seasonal population dynamics of thrips. Overall, the 2‐year results were generally consistent in trends of thrips incidence during the season, which may need to be considered when choosing vegetable planting dates in the region. [ABSTRACT FROM AUTHOR]

Tomato spotted wilt virus (TSWV) and related thrips-borne orthotospoviruses are a threat to food and ornamental crops. Orthotospoviruses have the capacity for rapid genetic change by genome segment reassortment and mutation. Genetic resistance is one of the most effective strategies for managing orthotospoviruses, but there are multiple examples of resistance gene breakdown. Our goal was to develop effective multigenic, broad-spectrum resistance to TSWV and other orthotospoviruses. The most conserved sequences for each open reading frame (ORF) of the TSWV genome were identified, and comparison with other orthotospoviruses revealed sequence conservation within virus clades; some overlapped with domains with well-documented biological functions. We made six hairpin constructs, each of which incorporated sequences matching portions of all five ORFs. Tomato plants expressing the hairpin transgene were challenged with TSWV by thrips and leaf-rub inoculation, and four constructs provided strong protection against TSWV in foliage and fruit. To determine if the hairpin constructs provided protection against other emerging orthotospoviruses, we challenged the plants with tomato chlorotic spot virus and resistance-breaking TSWV and found that the same constructs also provided resistance to these related viruses. Antiviral hairpin constructs are an effective way to protect plants from multiple orthotospoviruses and are an important strategy in the fight against resistance-breaking TSWV and emerging viruses. Targeting of all five viral ORFs is expected to increase the durability of resistance, and combining them with other resistance genes could further extend the utility of this disease control strategy. [ABSTRACT FROM AUTHOR]

Copyright of Çukurova Journal of Agriculture & Food Sciences is the property of Cukurova University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Capsicum annuum (CA) is grown outdoors across fields in Jeollabuk-do, South Korea. The weeds surrounding these fields were investigated regarding the infection of 11 viruses infecting CA during the year 2014–2018. In the reverse transcription polymerase chain reaction diagnosis, 546 out of 821 CA samples (66.5%) were infected by nine viruses, and 190 out of 918 weed samples (20.7%) were infected by eight viruses. Correlation analysis of the mutual influence of the viruses infecting CA and weeds during these 5 years showed that five viruses had significant positive correlations with the infection in both CA and weeds. Over the study period, the weeds infected by cucumber mosaic virus (CMV) in the previous year were positively correlated with the incidence of CMV infection in CA in the current year, although the correlation was lower for tomato spotted wilt virus (TSWV) compared to CMV. The CMV infection percent was 14.0% in summer annuals, 11.4% in perennials, and 7.8% in winter annuals. However, considering the overwintering period without CA, the infection percent was 5.2% higher in winter annuals and perennials than that in summer annuals, indicating that winter annual and perennial weeds served as the main habitats for insect vectors. The TSWV infection percent in weeds was 10.4% in summer annuals, 6.4% in winter annuals, and 6.2% in perennials. The weeds surrounding CA fields, acting as the intermediate hosts, were found to be the potent sources of infection, influencing the spread and diversity of CA-infecting viruses. The results of this study can contribute to prevent viral infection in agricultural fields.

The nonstructural protein NSm of tomato spotted wilt virus (TSWV) has been identified as the avirulence determinant of the tomato single dominant Sw‐5 resistance gene. Although Sw‐5 effectiveness has been shown for most TSWV isolates, the emergence of resistance‐breaking (RB) isolates has been observed. It is strongly associated with two point mutations (C118Y or T120N) in the NSm viral protein. TSWV‐like symptoms were observed in tomato crop cultivars (+Sw‐5) in the Baja California peninsula, Mexico, and molecular methods confirmed the presence of TSWV. Sequence analysis of the NSm 118–120 motif and three‐dimensional protein modelling exhibited a noncanonical C118F substitution in seven isolates, suggesting that this substitution could emulate the C118Y‐related RB phenotype. Furthermore, phylogenetic and molecular analysis of the full‐length genome (TSWV‐MX) revealed its reassortment‐related evolution and confirmed that putative RB‐related features are restricted to the NSm protein. Biological and mutational NSm 118 residue assays in tomato (+Sw‐5) confirmed the RB nature of TSWV‐MX isolate, and the F118 residue plays a critical role in the RB phenotype. The discovery of a novel TSWV‐RB Mexican isolate with the presence of C118F substitution highlights a not previously described viral adaptation in the genus Orthotospovirus, and hence, the necessity of further crop monitoring to alert the establishment of novel RB isolates in cultivated tomatoes. [ABSTRACT FROM AUTHOR]

We evaluated the suppressive effect of prohydrojasmon (PDJ) on Frankliniella occidentalis and tomato spotted wilt virus (TSWV) in chrysanthemums under semi-commercial conditions. The overhead sprinkling of plants with PDJ did not suppress the initial colonization of plants by released adult thrips. However, it significantly reduced subsequent feeding damage on leaves and the reproduction of larval offspring. Rates of 1 and 2 L/m2 of 0.8 mM PDJ equally suppressed F. occidentalis and feeding damage without phytotoxic effects, although 3 L/m2 reduced plant growth. Frequencies of 2 and 3 applications of PDJ at different intervals had similar inhibitory effects on F. occidentalis, suggesting the possibility of low-frequency, labor-saving applications in chrysanthemums. Weekly applications suppressed the occurrence of TSWV transmitted by viruliferous adult thrips dispersed from inoculum sources to a degree consistent with that of feeding damage, so PDJ might inhibit primary infection via disruption of feeding behavior. All our findings suggest that PDJ offers a valuable option for controlling F. occidentalis and orthotospovirus diseases transmitted by it in chrysanthemum production greenhouses. [ABSTRACT FROM AUTHOR]

An in-house tomato inbred line, YNAU335, was planted in a greenhouse in spring from 2014 to 2017, and showed immunity to tomato spotted wilt virus (TSWV). YNAU335 was infected with TSWV in the spring from 2018 to 2020, and disease was observed on the leaves, sepals, and fruits. In 2021 and 2022, YNAU335 was planted in spring in the same greenhouse, which was suspected of being infected with TSWV, and visible disease symptoms were observed on the fruits. Transmission electron microscopy, deep sequencing of small RNAs, and molecular mutation diagnosis were used to analyze the pathological features and genetic polymorphism of TSWV infecting tomato fruit. Typical TSWV virions were observed in the infected fruits, but not leaves from YNAU335 grown between 2021 and 2022, and cross-infection was very rarely observed. The number of mitochondria and chloroplasts increased, but the damage to the mitochondria was greater than that seen in the chloroplasts. Small RNA deep sequencing revealed the presence of multiple viral species in TSWV-infected and non-infected tomato samples grown between 2014–2022. Many virus species, including TSWV, which accounted for the largest proportion, were detected in the TSWV-infected tomato leaves and fruit. However, a variety of viruses other than TSWV were also detected in the non-infected tissues. The amino acids of TSWV nucleocapsid proteins (NPs) and movement proteins (MPs) from diseased fruits of YNAU335 picked in 2021–2022 were found to be very diverse. Compared with previously identified NPs and MPs from TSWV isolates, those found in this study could be divided into three types: non-resistance-breaking, resistance-breaking, and other isolates. The number of positive clones and a comparison with previously identified amino acid mutations suggested that mutation F at AA118 of the MP (GenBank OL310707) is likely the key to breaking the resistance to TSWV, and this mutation developed only in the infected fruit of YNAU335 grown in 2021 and 2022. [ABSTRACT FROM AUTHOR]

Tomato spotted wilt virus (TSWV) has significant economic impact on horticulture worldwide. One of the five proteins encoded by TSWV genome is the multifunctional NSs protein, which is a viral suppressor of RNA silencing (VSR) besides functioning as the effector of Tsw resistance gene in resistant pepper cultivars. In this study we demonstrate the in vivo self-interaction of NSs protein using bimolecular fluorescence complementation and yeast two-hybrid assays, and propose that a highly charged alpha helix located at the second half of the protein is required for self-interaction. Furthermore, we confirmed that self-interaction is not required for its effector function on pepper. Moreover, self-interaction is dispensable for gene silencing suppressor activity, although it enhances the suppression efficiency.

Oxypetalum coeruleum, commonly known as Tweedia, is a perennial herbaceous plant of the Apocynaceae family native to southern Brazil and Uruguay. Tweedia plants are grown as one of the most popular ornamental flowers for floral arrangement in Korea. In May 2021, several tweedia plants in a single greenhouse in Gimje, Jeollabuk-do were found to show virus-like symptoms including necrotic rings, vein-clearing, chlorotic mottle, and mosaic on the leaves, and necrosis on the stems. Here, we have identified tomato spotted wilt virus (TSWV) in symptomatic tweedia leaves by applying high-throughput RNA sequencing. In the result, a single infection by TSWV was verified without mixed infections of different virus species. To confirm the presence of TSWV, a reverse transcription polymerase chain reaction was performed with a specific primer set to the N gene of TSWV. The complete genomic sequence of L, M, and S segments of TSWV ‘Oxy’ isolate were determined and deposited in GenBank under accession numbers LC671525, LC671638, and LC671639, respectively. In the phylogenetic tree analysis by maximum likelihood method, ‘Oxy’ isolate showed a high relationship with TSWV ‘Gumi’ isolate from Gerbera jamesonii in Gyeongsangbuk-do, Korea; for all three RNA segments. To our knowledge, this is the first report of TSWV infection of O. coeruleum in Korea.

We deployed field-based high-throughput phenotyping (HTP) techniques to acquire trait data for a subset of a peanut chromosome segment substitution line (CSSL) population. Sensors mounted on an unmanned aerial vehicle (UAV) were used to derive various vegetative indices as well as canopy temperatures. A combination of aerial imaging and manual scoring showed that CSSL 100, CSSL 84, CSSL 111, and CSSL 15 had remarkably low tomato spotted wilt virus (TSWV) incidence, a devastating disease in South Georgia, USA. The four lines also performed well under leaf spot pressure. The vegetative indices showed strong correlations of up to 0.94 with visual disease scores, indicating that aerial phenotyping is a reliable way of selecting under disease pressure. Since the yield components of peanut are below the soil surface, we deployed ground penetrating radar (GPR) technology to detect pods non-destructively. Moderate correlations of up to 0.5 between pod weight and data acquired from GPR signals were observed. Both the manually acquired pod data and GPR variables highlighted the three lines, CSSL 84, CSSL 100, and CSSL 111, as the best-performing lines, with pod weights comparable to the cultivated check Tifguard. Through the combined application of manual and HTP techniques, this study reinforces the premise that chromosome segments from peanut wild relatives may be a potential source of valuable agronomic traits. [ABSTRACT FROM AUTHOR]

Tomato is one of the most cultivated vegetables in the world. In this context, intensive tomato breeding studies are carried out around the world and new cultivars are emerging every day, which leads to great competition. In particular, resistance or tolerance levelstolerance levels to some important diseases and pests are considered important in cultivar breeding and in determining the commercial value of cultivars. In this context, the determination of resistance levels to 70 tomatoes, Meloidogyne incognita, Tomato Yellow leaf curling virus (Tylcv), Verticillium wilt, Fusarium oxysporum radicis, Tomato spotted wilt virus (TSWV), Fusarium Wilt, which have the potential to become parent lines at S8 level due to their agromorphological characteristics formed the subject of this study. When the results of the study are examined, tomato genotypes showed resistance/sensitive levels according to combinations of alleles as 58 genotypes of RR (homozygous resistant), 10 Rr (heterozygous), 2 rr(sensitive) to Meloidogyne incognita, 45 RR (homozygous resistant), 15 Rr (heterozygous),10 rr (sensitive)to Verticillium dahliae, 10 to, 52 RR (homozygous resistant), 13 Rr (heterozygous), 5 rr (sensitive) to Tomato Spotted Wilt Virus, 46 RR (homozygous resistant) 18 Rr (heterozygous), 6 rr (sensitive) to Tomato Yellow leaf Curl Virus, Fusarium oxysporum (Fusarium wilt) 49 RR (homozygous resistant), 13 Rr (heterozygous), 8 rr (sensitive), Fusarium oxysporum radicis (Frl) 52 Their resistances were determined as RR (homozygous resistant), 12 Rr (heterozygous), 6 rr (sensitive). [ABSTRACT FROM AUTHOR]

CRISPR/Cas genome-editing tools provide unprecedented opportunities for basic plant biology research and crop breeding. However, the lack of robust delivery methods has limited the widespread adoption of these revolutionary technologies in plant science. Here, we report an efficient, non-transgenic CRISPR/Cas delivery platform based on the engineered tomato spotted wilt virus (TSWV), an RNA virus with a host range of over 1000 plant species. We eliminated viral elements essential for insect transmission to liberate genome space for accommodating large genetic cargoes without sacrificing the ability to infect plant hosts. The resulting non-insect-transmissible viral vectors enabled effective and stable in planta delivery of Cas12a and Cas9 nucleases as well as adenine and cytosine base editors. In systemically infected plant tissues, the deconstructed TSWV-derived vectors induced efficient somatic gene mutations and base conversions in multiple crop species with little genotype dependency. Plants with heritable, bi-allelic mutations could be readily regenerated by culturing the virus-infected tissues in vitro without antibiotic selection. Moreover, we showed that antiviral treatment with ribavirin during tissue culture cleared the viral vectors in 100% of regenerated plants and further augmented the recovery of heritable mutations. Because many plants are recalcitrant to stable transformation, the viral delivery system developed in this work provides a promising tool to overcome gene delivery bottlenecks for genome editing in various crop species and elite varieties. In this study, tomato spotted wilt virus (TSWV) was engineered into viral vectors for safe, effective, and DNA-free delivery of large CRISPR/Cas enzymes in multiple crop species/genotypes. Virus-free plants with heritable mutations were regenerated with high efficiency from infected somatic tissues upon antiviral treatment. The TSWV-based delivery system is promising to overcome gene delivery bottlenecks for genome editing in various crop species and elite varieties. [ABSTRACT FROM AUTHOR]

Copyright of Arab Journal of Plant Protection is the property of Arab Society for Plant Protection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Tomato spotted wilt virus (TSWV) has significant economic impact on horticulture worldwide. One of the five proteins encoded by TSWV genome is the multifunctional NSs protein, which is a viral suppressor of RNA silencing (VSR) besides functioning as the effector of Tsw resistance gene in resistant pepper cultivars. In this study we demonstrate the in vivo self-interaction of NSs protein using bimolecular fluorescence complementation and yeast two-hybrid assays, and propose that a highly charged alpha helix located at the second half of the protein is required for selfinteraction. Furthermore, we confirmed that self-interaction is not required for its effector function on pepper. Moreover, self-interaction is dispensable for gene silencing suppressor activity, although it enhances the suppression efficiency. [ABSTRACT FROM AUTHOR]

Background: Tomato spot wilt virus (TSWV) and tomato yellow leaf curl virus (TYLCV) are highly harmful viruses in agricultural production, which can cause serious economic losses to crops and even devastating consequences for vegetable yield in some countries and regions. Although the two viruses belong to different families and have different transmission vectors, they share most hosts. Objective: This study aimed to examine the transcriptomic expression of single and mixed inoculations of TSWV and TYLCV, leading to antagonism using high-throughput RNA sequencing. Methods: We confirmed the single and mixed infections of these viruses in Nicotiana benthamiana (N. benthamiana) by artificial inoculation. And the expression changes of related genes and their biological functions and pathways during the mixed infection of TSWV and TYLCV were analyzed by comparative transcriptome. Results: Basically, similar symptoms were observed in the plants singly infected with TSWV and co-infected with TYLCV; the symptoms of TYLCV in the co-infected plants were not obvious compared with single TYLCV infections. When inoculated with TYLCV, the accumulation of the virus significantly reduced in single and mixed infections with TSWV; the TSWV accumulated slightly less in co-infection with TYLCV, whereas this reduction was much smaller than that of TYLCV. The results suggested that TSWV had an antagonistic effect on the accumulation of TYLCV in N. benthamiana. It mainly focused on the changes in unique differentially expressed genes (DEGs) caused by the co-infection of TSWV and TYLCV. The eight pathways enriched by upregulated DEGs mainly included amino acid biosynthesis, citrate cycle (or tricarboxylic acid cycle, TCA cycle), and so on. However, only pentose phosphate pathway (PPP) and peptidoglycan biosynthesis could be downregulated in the Kyoto Encyclopedia of Genes and Genomes pathway in which peptidoglycan biosynthesis was involved in upregulated and downregulated pathways. Conclusions: The antagonistic effect of TSWV on TYLCV in N.benthamiana and the change trends and specific pathways of DEGs in this process were found. Our study provided new insights into the host regulation and competition between viruses in response to TSWV and TYLCV mixed infection. [ABSTRACT FROM AUTHOR]

Tobacco (Nicotiana tabacum L.) is an important industrial crop. Among the diseases causing losses in tobacco cultivation, viral ones are of particular importance due to the very low effectiveness of chemical protection allowing only for vector control. The greatest threat to tobacco cultivation in Poland and in many countries of the world is posed by potato virus Y (PVY), tomato spotted wilt virus (TSWV) and, in recent years, the increasingly frequent tobacco mosaic virus (TMV). The genetic resources studies carried out in the genus Nicotiana have shown a wide variation in species resistance, assessed biologically, serologically and molecularly, depending on the virus used and, in the case of PVY, also on the specific isolate. The results of the assessment of resistance in Nicotiana accessions presented in this paper, gathered from literature data as well as from our own research, allow us to broaden and systematise our knowledge on the sources of resistance to viral diseases. This is the only such an extensive study in this field. It provides an excellent information base for the appropriate selection of accessions for use in resistance breeding. [ABSTRACT FROM AUTHOR]

The Polish germplasm collection of Nicotiana tabacum was started in the 1920s. Up to now, more than eight hundred accessions originating from different regions of the world have been gathered in the collection. It includes valuable breeding lines and obsolete cultivars, among them cytoplasmic male-sterile lines. Numerous cultivars are rich sources of features desired in tobacco breeding. Therefore, the accessions are continually characterised in terms of their various features, one of the most important of which is disease resistance. Much research is being done to explain the nature of resistance and its genetic basis. Moreover, cultivars with good agronomic characteristics are used in wide hybridisation, being recipients of resistance genes from wild species or are genetically modified with transgenes conditioning resistance. The biological diversity of cultivars also allows a proper selection of plant material for pathogen studies, while the large number of the accessions facilitates research into the conditions for long seed storage. Numerous examples of the use of Polish tobacco germplasm in research and breeding, specifically in disease resistance, have been presented in this paper. [ABSTRACT FROM AUTHOR]

Phytohormones play important roles in plant immunity. Recently, Chen et al. discovered that the tomato spotted wilt virus attacks the plant hormone receptor to promote infection. Plants evolved an immune receptor to mimic the attacked hormone receptors to recognize the virus, thereby activating a robust immune response. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Oil Crop Sciences is the property of Oil Crops Research Institute of Chinese Academy of Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Tomato spotted wilt virus (TSWV) poses a serious threat to tomato (Solanum lycopersicum) production. In this study, tomato inbred line YNAU335 was developed without the Sw-5 locus, which confers resistance or immunity to TSWV (absence of infection). Genetic analysis demonstrated that immunity to TSWV was controlled by a dominant nuclear gene. The candidate genes were mapped into a 20-kb region in the terminal of the long arm of chromosome 9 using bulk segregant analysis and linkage analysis. In this candidate region, a chalcone synthase–encoding gene (SlCHS3) was identified as a strong candidate gene for TSWV resistance. Silencing SlCHS3 reduced flavonoid synthesis, and SlCHS3 overexpression increased flavonoid content. The increase in flavonoids improved TSWV resistance in tomato. These findings indicate that SlCHS3 is indeed involved in the regulation of flavonoid synthesis and plays a significant role in TSWV resistance of YNAU335. This could provide new insights and lay the foundation for analyzing TSWV resistance mechanisms. [ABSTRACT FROM AUTHOR]

Mesoionic structures have become important advancements in recent agrochemical design. However, their potential beyond serving as excellent insecticides remains unexplored with limited reports available. Herein, a series of imidazo[1,2- a ]pyridine mesoionics were developed by structurally incorporating sulfonyl piperazine moieties into imidazo[1,2- a ]pyridines. Many of the obtained derivatives demonstrated bioactivity against tomato spotted wilt virus (TSWV) in bioassays. In particular, compound Z40 , identified via three-dimensional quantitative structure activity relation models, displayed encouraging protective performance (half-maximal effect concentration = 252 μg/mL) compared to the positive controls ningnanmycin (332 μg/mL) and vanisulfane (523 μg/mL). Through defense enzyme assays, real-time quantitative polymerase chain reaction, and proteomics analysis, Z40 was identified as a plant immunomodulator that promotes defense enzyme activity and the mediates oxidative phosphorylation pathway, enabling plants to resist TSWV. We expect this study to help expand the possibilities of mesoionic compounds.

Abstract Background The gut is the first barrier to infection by viruses that are internally borne and transmitted persistently by arthropod vectors to plant and animal hosts. Tomato spotted wilt virus (TSWV), a plant-pathogenic virus, is transmitted exclusively by thrips vectors in a circulative-propagative manner. Frankliniella occidentalis (western flower thrips), the principal thrips vector of TSWV, is transmission-competent only if the virus is acquired by young larvae. To begin to understand the larval gut response to TSWV infection and accumulation, a genome-assisted, transcriptomic analysis of F. occidentalis gut tissues of first (early L1) and second (early L2 and late L2) instar larvae was conducted using RNA-Seq to identify differentially-expressed transcripts (DETs) in response to TSWV compared to non-exposed cohorts. Results The larval gut responded in a developmental stage-dependent manner, with the majority of DETs (71%) associated with the early L1 stage at a time when virus infection is limited to the midgut epithelium. Provisional annotations of these DETs inferred roles in digestion and absorption, insect innate immunity, and detoxification. Weighted gene co-expression network analysis using all assembled transcripts of the gut transcriptome revealed eight gene modules that distinguish larval development. Intra-module interaction network analysis of the three most DET-enriched modules revealed ten central hub genes. Droplet digital PCR-expression analyses of select network hub and connecting genes revealed temporal changes in gut expression during and post exposure to TSWV. Conclusions These findings expand our understanding of the developmentally-mediated interaction between thrips vectors and orthotospoviruses, and provide opportunities for probing pathways for biomarkers of thrips vector competence.

Plant viruses cause significant yield losses, continuously compromising crop production and thus representing a serious threat to global food security. Tomato spotted wilt virus (TSWV) is the most harmful plant virus that mainly infects horticultural crops and has a wide host range. Reverse-transcription quantitative real-time PCR (RT-qPCR) has been widely used for detecting TSWV with high sensitivity, but its application is limited owing to the lack of standardization. Therefore, in this study, a sensitive and accurate reverse transcription droplet digital polymerase chain reaction (RT-ddPCR) method was established for TSWV detection. Additionally, we compared the sensitivities of RT-qPCR and RT-ddPCR for TSWV detection. Specificity analysis of RT-ddPCR for TSWV showed no amplification for main pepper viruses and negative control. TSWV transcripts levels measured by RT-ddPCR and RT-qPCR showed a high degree of linearity; however, the former yielded results that were at least 10-fold more sensitive and detected lower TSWV copy numbers than the latter. Collectively, our findings show that RT-ddPCR provides improved analytical sensitivity and specificity for TSWV detection, making it suitable for identifying low TSWV concentrations in field samples.

Tospoviruses infect numerous crop species worldwide, causing significant losses throughout the supply chain. As a defence mechanism, plants use RNA interference (RNAi) to generate virus-derived small-interfering RNAs (vsiRNAs), which target viral transcripts for degradation. Small RNA sequencing and in silico analysis of capsicum and N. benthamiana infected by tomato spotted wilt virus (TSWV) or capsicum chlorosis virus (CaCV) demonstrated the presence of abundant vsiRNAs, with host-specific differences evident for each pathosystem. Despite the biogenesis of vsiRNAs in capsicum and N. benthamiana, TSWV and CaCV viral loads were readily detectable. In response to tospovirus infection, the solanaceous host species also generated highly abundant virus-activated small interfering RNAs (vasiRNAs) against many endogenous transcripts, except for an N. benthamiana accession lacking a functional RDR1 gene. Strong enrichment for ribosomal protein-encoding genes and for many genes involved in protein processing in the endoplasmic reticulum suggested co-localisation of viral and endogenous transcripts as a basis for initiating vasiRNA biogenesis. RNA-seq and RT-qPCR-based analyses of target transcript expression revealed an inconsistent role for vasiRNAs in modulating gene expression in N. benthamiana, which may be characteristic of this tospovirus-host pathosystem. [ABSTRACT FROM AUTHOR]

In June 2019, Angelica acutiloba plants showing virus-like symptoms such as chlorotic local lesion and mosaic on the leaves were found in a greenhouse in Nonsan, South Korea. To identify the causal virus, we collected 6 symptomatic A. acutiloba leaf samples and performed reverse transcription polymerase chain reaction (RT-PCR) analysis using specific detection primers for three reported viruses including tomato spotted wilt virus (TSWV). RT-PCR results showed that five symptomatic samples were positive for TSWV. Mechanical sap inoculation of one of the collected TSWV isolate (TSWV-NS-AG28) induced yellowing, chlorosis and mosaic symptoms in A. acutiloba and necrotic local lesions and mosaic in Solanaceae species. Phylogenetic analysis based on the complete genome sequences showed that TSWV-NS-AG28 had a maximum nucleotide identity with TSWV-NS-BB20 isolated from butterbur in Nonsan, South Korea. To our knowledge, this is the first report of TSWV infection in A. acutiloba.

In May 2020, necrosis and necrotic ring patterns were observed on leaves of three of 140 Iris domestica plants in a demonstration garden in Wanju, Jeollabuk-do. Three symptomatic plants were found to be infected by tomato spotted wilt virus (TSWV). To analyze the whole genomic sequence of one TSWV isolate, ’Blackberry lilykr1’, L, M, and S genome segments were sequenced and analyzed by comparison of nucleotide sequences of the three segments with corresponding sequences of other TSWV isolates. ‘Blackberry lily-kr1’ isolate was most closely related to ‘JJ’ isolate (MF159046) or ‘HJ’ isolate (LC273305) in the L segment, and to ‘JJ’ isolate (MF159058 and KY021439) in the M and S segments, respectively. Phylogenetic analysis by Maximum likelihood method using MEGA X program with ‘Blackberry lily-kr1’ isolate showed high relationship with ‘JJ’ pepper isolate or ‘HJ’ Humulus japonicas isolate in the all three segment. Necrosis and double ring patterns on leaves were formed in the glasshouse after inoculation of healthy I. domestica plants with sap of ‘Blackberry lily-kr1’-infected Nicotiana rustica plants. This result suggests that I. domestica plants showing necrotic ring patterns in the open field are caused by TSWV infection. This is the first report of TSWV infection of I. domestica in Korea.

Several studies have showed that the nucleotide and dinucleotide composition of viruses possibly follows their host species or protein coding region. Nevertheless, the influence of viral segment on viral nucleotide and dinucleotide composition is still unknown. Here, we explored through tomato spotted wilt virus (TSWV), a segmented virus that seriously threatens the production of tomatoes all over the world. Through nucleotide composition analysis, we found the same over-representation of A across all viral segments at the first and second codon position, but it exhibited distinct in segments at the third codon position. Interestingly, the protein coding regions which encoded by the same or different segments exhibit obvious distinct nucleotide preference. Then, we found that the dinucleotides UpG and CpU were overrepresented and the dinucleotides UpA, CpG and GpU were underrepresented, not only in the complete genomic sequences, but also in different segments, protein coding regions and host species. Notably, 100% of the data investigated here were predicted to the correct viral segment and protein coding region, despite the fact that only 67% of the data analyzed here were predicted to the correct viral host species. In conclusion, in case study of TSWV, nucleotide composition and dinucleotide preference of segment viruses are more strongly dependent on segment and protein coding region than on host species. This research provides a novel perspective on the molecular evolutionary mechanisms of TSWV and provides reference for future research on genetic diversity of segmented viruses. • The nucleotide composition of TSWV exhibits distinct in segments at the third codon position that the highest proportion of A-nucleotides is still present in segment L, but changed from A to U in segment M and segment S. • The protein coding regions which encoded by the same or different segments exhibit obvious distinct nucleotide preference. • The dinucleotides UpG and CpU were overrepresented and the dinucleotides UpA, CpG and GpU were underrepresented. • The nucleotide composition and dinucleotide preference of TSWV are more strongly dependent on segment and protein coding region than on host species. [ABSTRACT FROM AUTHOR]

We deployed field-based high-throughput phenotyping (HTP) techniques to acquire trait data for a subset of a peanut chromosome segment substitution line (CSSL) population. Sensors mounted on an unmanned aerial vehicle (UAV) were used to derive various vegetative indices as well as canopy temperatures. A combination of aerial imaging and manual scoring showed that CSSL 100, CSSL 84, CSSL 111, and CSSL 15 had remarkably low tomato spotted wilt virus (TSWV) incidence, a devastating disease in South Georgia, USA. The four lines also performed well under leaf spot pressure. The vegetative indices showed strong correlations of up to 0.94 with visual disease scores, indicating that aerial phenotyping is a reliable way of selecting under disease pressure. Since the yield components of peanut are below the soil surface, we deployed ground penetrating radar (GPR) technology to detect pods non-destructively. Moderate correlations of up to 0.5 between pod weight and data acquired from GPR signals were observed. Both the manually acquired pod data and GPR variables highlighted the three lines, CSSL 84, CSSL 100, and CSSL 111, as the best-performing lines, with pod weights comparable to the cultivated check Tifguard. Through the combined application of manual and HTP techniques, this study reinforces the premise that chromosome segments from peanut wild relatives may be a potential source of valuable agronomic traits.

Biochar is a rich carbon product obtained by pyrolysis of biomass under a limited supply of oxygen. It is composed mainly of aromatic molecules, but its agronomic value is hard to evaluate and difficult to predict due to its great variable characteristics depending on the type of starting biomass and the conditions of pyrolysis. Anyway, it could be used as soil amendment because it increases the soil fertility of acidic soils, increases the agricultural productivity, and seems to provide protection against some foliar and soilborne diseases. In this study, the effects of biochar, obtained from olive pruning, have been evaluated on tomato seedlings growth and on their response to systemic agents' infection alone or added with beneficial microorganisms (Bacillus spp. and Trichoderma spp.). First, experimental data showed that biochar seems to promote the development of the tomato seedlings, especially at concentrations ranging from 1 to 20% (w/w with peat) without showing any antimicrobial effects on the beneficial soil bacteria at the tomato rhizosphere level and even improving their growth. Thus, those concentrations were used in growing tomato plants experimentally infected with tomato spotted wilt virus (TSWV) and potato spindle tuber viroid (PSTVd). The biochar effect was estimated by evaluating three parameters, namely, symptom expression, number of infected plants, and pathogen quantification, using RT-qPCR technique and −ΔΔCt analysis. Biochar at 10–15% and when added with Trichoderma spp. showed that it reduces the replication of PSTVd and the expression of symptoms even if it was not able to block the start of infection. The results obtained on TSWV-infected plants suggested that biochar could contribute to reducing both infection rate and virus replication. For systemic viral agents, such as PSTVd and TSWV, there are no curative control methods, and therefore, the use of prevention means, as can be assumed the use biochar, for example, in the nursery specialized in horticultural crops, can be of great help. These results can be an encouraging starting point to introduce complex biochar formulates among the sustainable managing strategies of plant systemic diseases. [ABSTRACT FROM AUTHOR]

Sw‐5b is an effective resistance gene used widely in tomato to control tomato spotted wilt virus (TSWV), which causes severe losses in crops worldwide. Sw‐5b confers resistance by recognizing a 21‐amino‐acid peptide region of the viral movement protein NSm (NSm21, amino acids 115–135). However, C118Y or T120N mutation within this peptide region of NSm has given rise to field resistance‐breaking (RB) TSWV isolates. To investigate the potential ability of TSWV to break Sw‐5b‐mediated resistance, we mutagenized each amino acid on NSm21 and determined which amino acid mutations would evade Sw‐5b recognition. Among all alanine‐scan mutants, NSmP119A, NSmW121A, NSmD122A, NSmR124A, and NSmQ126A failed to induce a hypersensitive response (HR) when coexpressed with Sw‐5b in Nicotiana benthamiana leaves. TSWV with the NSmP119A, NSmW121A, or NSmQ126A mutation was defective in viral cell‐to‐cell movement and systemic infection, while TSWV carrying the NSmD122A or NSmR124A mutation was not only able to infect wild‐type N. benthamiana plants systemically but also able to break Sw‐5b‐mediated resistance and establish systemic infection on Sw‐5b‐transgenic N. benthamiana plants. Two improved mutants, Sw‐5bL33P/K319E/R927A and Sw‐5bL33P/K319E/R927Q, which we recently engineered and which provide effective resistance against field RB isolates carrying NSmC118Y or NSmT120N mutations, recognized all NSm21 alanine‐substitution mutants and conferred effective resistance against new experimental RB TSWV with the NSmD122A or NSmR124A mutation. Collectively, we determined the key residues of NSm for Sw‐5b recognition, investigated their potential RB ability, and demonstrated that the improved Sw‐5b mutants could provide effective resistance to both field and potential RB TSWV isolates. [ABSTRACT FROM AUTHOR]

To identify host factors for tomato spotted wilt orthotospovirus (TSWV), a virus‐induced gene silencing (VIGS) screen using tobacco rattle virus (TRV) was performed on Nicotiana benthamiana for TSWV susceptibility. To rule out any negative effect on the plants' performance due to a double viral infection, the method was optimized to allow screening of hundreds of clones in a standardized fashion. To normalize the results obtained in and between experiments, a set of controls was developed to evaluate in a consist manner both VIGS efficacy and the level of TSWV resistance. Using this method, 4532 random clones of an N. benthamiana cDNA library were tested, resulting in five TRV clones that provided nearly complete resistance against TSWV. Here we report on one of these clones, of which the insert targets a small gene family coding for the ribosomal protein S6 (RPS6) that is part of the 40S ribosomal subunit. This RPS6 family is represented by three gene clades in the genome of Solanaceae family members, which were jointly important for TSWV susceptibility. Interestingly, RPS6 is a known host factor implicated in the replication of different plant RNA viruses, including the negative‐stranded TSWV and the positive‐stranded potato virus X. [ABSTRACT FROM AUTHOR]

The Sw5 gene cluster furnishes robust resistance to Tomato spotted wilt virus in tomato, which has led to its widespread applicability in agriculture. Among the five orthologs, Sw5b functions as a resistance gene against a broad-spectrum tospovirus and is linked with tospovirus resistance. However, its paralog Sw5a has been recently implicated in providing resistance against Tomato leaf curl New Delhi virus, broadening the relevance of the Sw5 gene cluster in promoting defense against plant viruses. We propose that plants have established modifications within the homologs of R genes that permit identification of different effector proteins and provide broad and robust resistance against different pathogens through activation of the hypersensitive response and cell death. [ABSTRACT FROM AUTHOR]

Biochar is a rich carbon product obtained by pyrolysis of biomass under a limited supply of oxygen. It is composed mainly of aromatic molecules, but its agronomic value is hard to evaluate and difficult to predict due to its great variable characteristics depending on the type of starting biomass and the conditions of pyrolysis. Anyway, it could be used as soil amendment because it increases the soil fertility of acidic soils, increases the agricultural productivity, and seems to provide protection against some foliar and soilborne diseases. In this study, the effects of biochar, obtained from olive pruning, have been evaluated on tomato seedlings growth and on their response to systemic agents' infection alone or added with beneficial microorganisms (Bacillus spp. and Trichoderma spp.). First, experimental data showed that biochar seems to promote the development of the tomato seedlings, especially at concentrations ranging from 1 to 20% (w/w with peat) without showing any antimicrobial effects on the beneficial soil bacteria at the tomato rhizosphere level and even improving their growth. Thus, those concentrations were used in growing tomato plants experimentally infected with tomato spotted wilt virus (TSWV) and potato spindle tuber viroid (PSTVd). The biochar effect was estimated by evaluating three parameters, namely, symptom expression, number of infected plants, and pathogen quantification, using RT-qPCR technique and −ΔΔCt analysis. Biochar at 10–15% and when added with Trichoderma spp. showed that it reduces the replication of PSTVd and the expression of symptoms even if it was not able to block the start of infection. The results obtained on TSWV-infected plants suggested that biochar could contribute to reducing both infection rate and virus replication. For systemic viral agents, such as PSTVd and TSWV, there are no curative control methods, and therefore, the use of prevention means, as can be assumed the use biochar, for example, in the nursery specialized in horticultural crops, can be of great help. These results can be an encouraging starting point to introduce complex biochar formulates among the sustainable managing strategies of plant systemic diseases.

Burdock (Arctium lappa L., belongs to the family Asteraceae), is an edible plant and an oriental medicinal herb in Korea (Han and Koo, 1993). In July 2023, burdocks showing chlorotic ringspots and yellowing on the leaves were observed in nine of approximately 4,000 plants in a greenhouse in Daegu, South Korea. To determine the causal virus species, nine symptomatic leaves from each individual plant were collected and tested using commercially available immunostrips (Agdia, Elkhart, USA) for cucumber mosaic virus (CMV) and tomato spotted wilt virus (TSWV). Seven out of nine samples tested positive for TSWV only. TSWV in South Korea was first reported on sweet pepper from Yesan in 2004 (Kim et al., 2004) and has since spread to various crops. The first report of TSWV infecting burdock plants in the world was from Hawaii in 1995 (Bautista et al., 1995), but TSWV-infected burdock has not been reported in Korea. To further confirm the presence of TSWV, total RNA was extracted from TSWV-positive burdock leaves using the RNeasy Plant Mini Kit (Qiagen, Hilden, Germany) and used in reverse transcription-polymerase chain reaction (RT-PCR) assays with a specific primer set that amplifies 777 bp of nucleocapsid gene (N gene) of TSWV (Yoon et al., 2014). To obtain the complete genome sequence of this TSWV in the burdock plant, named TSWV-DG, fragments of L, M, and S segments were amplified and sequenced. The complete genome sequences of the L (8914 nt), M (4773 nt), and S (2946 nt) segments were obtained by overlapping RT-PCR amplicons. RT-PCR products were cloned into the pGEM-T Easy vector, and selected DNA clones were sequenced using Sanger method (Bioneer, Korea). The complete genome sequences were deposited to GenBank (LC790665, LC790666, and LC790667, respectively). BLASTn analysis showed that sequences of each TSWV-DG segment had maximum nucleotide identities of 99.5%, 99.5%, and 99.5% with TSWV-L, TSWV-M, and TSWV-S (OM154971, OM154970, and OM154969, respectively), which were isolated from water dropwort (Oenanthe crocata) in China (Qiu et al., 2023). To assess the biological activity of TSWV-DG, A. lappa and Nicotiana benthamiana were inoculated mechanically with sap from infected burdock leaves and maintained for visual inspection of virus symptoms at 25 ℃ at 3 weeks. TSWV-DG produced symptoms on the systemic leaves of A. lappa, that included chlorotic spots and yellowing, and on the leaves of N. benthamiana, that included chlorotic spots and mosaic patterns from 14 days-post-inoculation. Meanwhile, mock-inoculated A.lappa and N.benthamiana remained symptomless. The presence of TSWV on the inoculated leaves was subsequently confirmed through Immunostrip and RT-PCR analyses. TSWV may pose a significant threat to the production of A. lappa, which is cultivated as both leafy greens and root vegetables in Korea. Furthermore, A. lappa may not only be at risk of damage from TSWV infection but also act as a potential source of TSWV infection, thereby posing a risk of transmission to other key crops in Korea, such as pepper or potato (Yoon et al., 2014). This is the first report TSWV infecting burdock in South Korea.

Background: The gut is the first barrier to infection by viruses that are internally borne and transmitted persistently by arthropod vectors to plant and animal hosts. Tomato spotted wilt virus (TSWV), a plant-pathogenic virus, is transmitted exclusively by thrips vectors in a circulative-propagative manner. Frankliniella occidentalis (western flower thrips), the principal thrips vector of TSWV, is transmission-competent only if the virus is acquired by young larvae. To begin to understand the larval gut response to TSWV infection and accumulation, a genome-assisted, transcriptomic analysis of F. occidentalis gut tissues of first (early L1) and second (early L2 and late L2) instar larvae was conducted using RNA-Seq to identify differentially-expressed transcripts (DETs) in response to TSWV compared to non-exposed cohorts. Results: The larval gut responded in a developmental stage-dependent manner, with the majority of DETs (71%) associated with the early L1 stage at a time when virus infection is limited to the midgut epithelium. Provisional annotations of these DETs inferred roles in digestion and absorption, insect innate immunity, and detoxification. Weighted gene co-expression network analysis using all assembled transcripts of the gut transcriptome revealed eight gene modules that distinguish larval development. Intra-module interaction network analysis of the three most DET-enriched modules revealed ten central hub genes. Droplet digital PCR-expression analyses of select network hub and connecting genes revealed temporal changes in gut expression during and post exposure to TSWV. Conclusions: These findings expand our understanding of the developmentally-mediated interaction between thrips vectors and orthotospoviruses, and provide opportunities for probing pathways for biomarkers of thrips vector competence. [ABSTRACT FROM AUTHOR]

Summary: Plants use intracellular nucleotide‐binding leucine‐rich repeat immune receptors (NLRs) to recognize pathogen‐encoded effectors and initiate immune responses. Tomato spotted wilt virus (TSWV), which has been found to infect >1000 plant species, is among the most destructive plant viruses worldwide. The Sw‐5b is the most effective and widely used resistance gene in tomato breeding to control TSWV. However, broad application of tomato cultivars carrying Sw‐5b has resulted in an emergence of resistance‐breaking (RB) TSWV. Therefore, new effective genes are urgently needed to prevent further RB TSWV outbreaks. In this study, we conducted artificial evolution to select Sw‐5b mutants that could extend the resistance spectrum against TSWV RB isolates. Unlike regular NLRs, Sw‐5b detects viral elicitor NSm using both the N‐terminal Solanaceae‐specific domain (SD) and the C‐terminal LRR domain in a two‐step recognition process. Our attempts to select gain‐of‐function mutants by random mutagenesis involving either the SD or the LRR of Sw‐5b failed; therefore, we adopted a stepwise strategy, first introducing a NSmRB‐responsive mutation at the R927 residue in the LRR, followed by random mutagenesis involving the Sw‐5b SD domain. Using this strategy, we obtained Sw‐5bL33P/K319E/R927A and Sw‐5bL33P/K319E/R927Q mutants, which are effective against TSWV RB carrying the NSmC118Y or NSmT120N mutation, and against other American‐type tospoviruses. Thus, we were able to extend the resistance spectrum of Sw‐5b; the selected Sw‐5b mutants will provide new gene resources to control RB TSWV. [ABSTRACT FROM AUTHOR]

As one of the top 10 plant viruses, the severity of losses to crop productivity caused by the tomato spotted wilt virus (TSWV) has resulted in an urgent need to develop a more sensitive and rapid method of detection. In this study, we developed a CRISPR/Cas13a-based detection system to diagnose TSWV in tomato and western flower thrips (Frankliniella occidentalis). The detection system relies on recombinase polymerase amplification and Cas13a-mediated collateral cleavage activity. Positive results can be distinguished after 20 min by a significantly enhanced fluorescence signal. We tested the sensitivity of CRISPR/Cas13a-based detection system and found that the detection system that we developed has limits of detection that reaches 2.26 × 102 copies/μl and a 10-fold increase compared with the sensitivity of using RT-PCR to detect the virus. Furthermore, the CRISPR/Cas13a-based detection system has a high selectivity for the TSWV without interference from other viruses. The CRISPR/Cas13a-based detection system was utilized to detect the TSWV in samples of tomato leaves and the transmission vector F. occidentalis that were fully consistent with the results when RT-PCR was used to detect the virus. Schematic of CRISPR/Cas13-based virus detection. [ABSTRACT FROM AUTHOR]

Summary: Plant intracellular nucleotide‐binding leucine‐rich repeat (NLR) receptors play critical roles in mediating host immunity to pathogen attack. We use tomato Sw‐5b::tospovirus as a model system to study the specific role of the compartmentalized plant NLR in dictating host defenses against the virus at different infection steps.We demonstrated here that tomato NLR Sw‐5b distributes to the cytoplasm and nucleus, respectively, to play different roles in inducing host resistances against tomato spotted wilt orthotospovirus (TSWV) infection. The cytoplasmic‐enriched Sw‐5b induces a strong cell death response to inhibit TSWV replication. This host response is, however, insufficient to block viral intercellular and long‐distance movement. The nuclear‐enriched Sw‐5b triggers a host defense that weakly inhibits viral replication but strongly impedes virus intercellular and systemic movement. Furthermore, the cytoplasmic and nuclear Sw‐5b act synergistically to dictate a full host defense of TSWV infection.We further demonstrated that the extended N‐terminal Solanaceae domain (SD) of Sw‐5b plays critical roles in cytoplasm/nucleus partitioning. Sw‐5b NLR controls its cytoplasm localization. Strikingly, the SD but not coil‐coil domain is crucial for Sw‐5b receptor to import into the nucleus to trigger the immunity. The SD was found to interact with importins. Silencing both importin α and β expression disrupted Sw‐5b nucleus import and host immunity against TSWV systemic infection.Collectively, our findings suggest that Sw‐5b bifurcates disease resistances by cytoplasm/nucleus partitioning to block different infection steps of TSWV. The findings also identified a new regulatory role of extra domain of a plant NLR in mediating host innate immunity. [ABSTRACT FROM AUTHOR]

As one of the top 10 plant viruses, the severity of losses to crop productivity caused by the tomato spotted wilt virus (TSWV) has resulted in an urgent need to develop a more sensitive and rapid method of detection. In this study, we developed a CRISPR/Cas13a-based detection system to diagnose TSWV in tomato and western flower thrips (Frankliniella occidentalis). The detection system relies on recombinase polymerase amplification and Cas13a-mediated collateral cleavage activity. Positive results can be distinguished after 20 min by a significantly enhanced fluorescence signal. We tested the sensitivity of CRISPR/Cas13a-based detection system and found that the detection system that we developed has limits of detection that reaches 2.26 × 102 copies/μl and a 10-fold increase compared with the sensitivity of using RT-PCR to detect the virus. Furthermore, the CRISPR/Cas13a-based detection system has a high selectivity for the TSWV without interference from other viruses. The CRISPR/Cas13a-based detection system was utilized to detect the TSWV in samples of tomato leaves and the transmission vector F. occidentalis that were fully consistent with the results when RT-PCR was used to detect the virus.

The Polish germplasm collection of Nicotiana tabacum was started in the 1920s. Up to now, more than eight hundred accessions originating from different regions of the world have been gathered in the collection. It includes valuable breeding lines and obsolete cultivars, among them cytoplasmic male-sterile lines. Numerous cultivars are rich sources of features desired in tobacco breeding. Therefore, the accessions are continually characterised in terms of their various features, one of the most important of which is disease resistance. Much research is being done to explain the nature of resistance and its genetic basis. Moreover, cultivars with good agronomic characteristics are used in wide hybridisation, being recipients of resistance genes from wild species or are genetically modified with transgenes conditioning resistance. The biological diversity of cultivars also allows a proper selection of plant material for pathogen studies, while the large number of the accessions facilitates research into the conditions for long seed storage. Numerous examples of the use of Polish tobacco germplasm in research and breeding, specifically in disease resistance, have been presented in this paper.

The western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is an important, worldwide vector of two tospoviruses (Family Bunyaviridae; Genus Tospovirus), Impatiens necrotic spot virus (INSV) and Tomato spotted wilt virus (TSWV). In the Salinas Valley of California, INSV causes severe necrosis, stunting, and crop losses to lettuce (Lactuca sativa L.). Because broccoli (Brassica oleracea var. italica L.) and cauliflower (Brassica oleracea var. botrytis L.) are major rotation crops with lettuce in the Salinas Valley, it is critical to understand if these Brassicas influence the dispersal dynamics of F. occidentalis. In 2013 and 2014, surveys were conducted evaluating yellow sticky cards and plant samples in lettuce, broccoli, and cauliflower fields in three regions of the Salinas Valley. F. occidentalis were collected on sticky cards from April to November and on foliage in all three regions. Two-choice oviposition assays as well as no-choice and two-choice feeding assays were conducted where F. occidentalis adults were exposed to leaves of lettuce, broccoli, and cauliflower. A significantly greater number of eggs was found on lettuce than on broccoli or cauliflower leaves in the choice assay, whereas for the broccoli and cauliflower choice assay, the number of eggs retrieved was low and not significantly different between hosts. The number of F. occidentalis feeding spots and leaf area injury ratings were similar on broccoli and lettuce leaves but were significantly lower on cauliflower than on lettuce and broccoli leaves. The implications of these results on thrips and plant virus management are discussed. [ABSTRACT FROM AUTHOR]

Tomato is the world's second largest cultivated vegetable crop. Tomato spotted wilt virus (TSWV) and fusarium wilt (FW) are the two major biotic stresses in India limiting tomato production. Identification and utilization of resistant lines to realize the full genetic potential of varieties for yield gain is an eco-friendly approach. The present research work involved genetic diversity study of 48 genotypes, augmented from different exotic, and indigenous sources belonging to three species using SSR markers. A total of 195 alleles were generated by employing 84 polymorphic markers. The PIC value was ranged from 0.12 to 0.93. Two sub-populations (K = 2) were revealed by model based structure analysis. The cluster analysis using the UPGMA method classified the genotypes into 6 clusters. Pusa Ruby, EC-310310 and EC-620452 were found to be highly diverse. Molecular characterization of 48 genotypes with SSR markers divulged seven genotypes with Sw-5 gene and nine genotypes with I-2 gene showing resistance to TSWV and FW, respectively and further, on artificial screening, they were found to be phenotypically resistant. Out of 195 alleles generated from 84 polymorphic SSR markers, 43 alleles from 26 SSR markers were identified with positive average allele effect distributed across nine chromosomes and positive average allele effect was identified for the average weight of the fruit, the number of fruits formed per plant, and fusarium wilt PDI score. Fruit weight and fruit yield per plant registered a significant and positive correlations. The identified genotypes with varied backgrounds and performances will be very useful as diversified sources in resistant breeding programs of tomato. [ABSTRACT FROM AUTHOR]

The study was conducted in Tokat Center, Niksar, Erbaa and Pazar districts where peppers were grown in the summer of 2016, and leaf samples were collected from plants suspected of the virus. During the surveys, a total of 324 plant samples were collected and the infected pepper samples were subjected to DAS-ELISA test with (Tomato spotted wilt virus) TSWV-specific antiserum, and RT-PCR was performed with virus-specific primers. In DAS-ELISA studies, 324 plants were tested and 13% of the samples were found to be TSWV infected. Samples that were positive in ELISA test were subjected to RT-PCR with nucleocapsid gene specific primers in the S segment and three samples were sent for sequence analysis. According to results, Turkey TSWV isolates Np gene region have shown 98-99% nucleotide identity with the isolates from France and South Korea and grouped with them same group. [ABSTRACT FROM AUTHOR]

Tospoviruses infect numerous crop species worldwide, causing significant losses throughout the supply chain. As a defence mechanism, plants use RNA interference (RNAi) to generate virus-derived small-interfering RNAs (vsiRNAs), which target viral transcripts for degradation. Small RNA sequencing and in silico analysis of capsicum and N. benthamiana infected by tomato spotted wilt virus (TSWV) or capsicum chlorosis virus (CaCV) demonstrated the presence of abundant vsiRNAs, with host-specific differences evident for each pathosystem. Despite the biogenesis of vsiRNAs in capsicum and N. benthamiana, TSWV and CaCV viral loads were readily detectable. In response to tospovirus infection, the solanaceous host species also generated highly abundant virus-activated small interfering RNAs (vasiRNAs) against many endogenous transcripts, except for an N. benthamiana accession lacking a functional RDR1 gene. Strong enrichment for ribosomal protein-encoding genes and for many genes involved in protein processing in the endoplasmic reticulum suggested co-localisation of viral and endogenous transcripts as a basis for initiating vasiRNA biogenesis. RNA-seq and RT-qPCR-based analyses of target transcript expression revealed an inconsistent role for vasiRNAs in modulating gene expression in N. benthamiana, which may be characteristic of this tospovirus-host pathosystem.

Tomato spotted wilt virus (TSWV; Genus Orthotospovirus: Family Tospoviridae) is one of the most destructive viruses affecting a wide range of horticultural crops on a worldwide basis. In 2015 and 2016, 171 leaf and fruit samples from tomato (Solanum lycopersicum) plants with viral symptoms were collected from the fields in various regions of Iran. ELISA test revealed that the samples were infected by TSWV. The results of RT-PCR showed that the expected DNA fragments of about 819 bp in length were amplified using a pair of universal primer corresponding to the RNA polymerase gene and DNA fragments of ca 777 bp and 724 bp in length were amplified using specific primers that have been designed based on the nucleocapsid (N) and non-structural (NSs) genes, respectively. The amplified fragments were cloned into pTG19-T and sequenced. Sequence comparisons with those available in the GenBank showed that the sequences belong to TSWV. The high nucleotide identity and similarities of new sequences based on the L, N, and NSs genes showed that minor evolutionary differences exist amongst the isolates. The phylogenetic tree grouped all isolates six clades based on N and NSs genes. Phylogenetic analysis showed that the Iranian isolates were composed a new distinct clade based on a part of polymerase, N and NSs genes. To our knowledge, this is the first detailed study on molecular characterization and genetic diversity of TSWV isolates from tomato in Iran that could be known as new clade of TSWV isolates.