Pepper Virus Research Articles

Current knowledge and breeding strategies for management of aphid-transmitted viruses of pepper (Capsicum spp.) in Africa

Aphid-transmitted viruses cause significant losses in pepper production worldwide, negatively affecting yield and quality. The emergence of new aphid-transmitted viruses or development of variants as well as the occurrence in mixed infections make management a challenge. Here, we overview the current status of the distribution, incidence and phylogeny of aphids and the viruses they transmit in pepper in Africa; outline the available genetic resources, including sources of resistance, resistance genes and molecular markers; and discuss the recent advances in understanding the genetic basis of resistance to the predominant African viruses infecting pepper. Pepper veinal mottle virus (PVMV; Potyvirus); Potato virus Y (PVY; Potyvirus), Chili veinal mottle virus (ChiVMV; Potyvirus), Cucumber mosaic virus (CMV; Cucumovirus) and Pepper veins yellow virus (PeVYV; Polerovirus) have been reported to be the most widespread and devastating aphid-transmitted viruses infecting pepper across Africa. Co-infection or mixed infection between aphid-transmitted viruses has been detected and the interrelationship between viruses that co-infect chili peppers is poorly understood. Establishing and evaluating existing and new diversity sets with more genetic diversity is an important component of developing host resistance and implementing integrated management strategies. However, more work needs to be done to characterize the aphid-transmitted viral strains across Africa and understand their phylogeny in order to develop more durable host resistance. In addition, a limited number of QTLs associated with resistance to the aphid-transmitted virus have been reported and QTL data are only available for PVY, ChiVMV and CMV mainly against European and Asian strains, although PVMV is likely the most important aphid-transmitted viral disease in Africa. There is a need to identify germplasm resources with resistance against various aphid-transmitted virus strains, and subsequent pyramiding of the resistance using marker-assisted selection could be an effective strategy. The recent advances in understanding the genetic basis of the resistance to the virus and the new breeding techniques that can be leveraged to accelerate breeding for aphid-transmitted virus in pepper are proposed as strategies to more efficiently develop resistant cultivars. The deployment of multi-genetic resistances in pepper is an effective and desirable method of managing viral-diseases in Africa and limit losses for farmers in a sustainable manner.

Occurrence, Complete Genome Sequencing, and Development of Diagnostics for Black Pepper Virus F Infecting Black Pepper in India

ABSTRACTThe occurrence of black pepper virus F (BPVF) was identified for the first time from India, and its complete genome sequence was determined using overlapping fragments obtained through reverse transcription polymerase chain reaction (RT‐PCR). The RNA 1 and RNA 2 of the Indian isolate of BPVF (BPVF‐IND) contained 6376 and 3340 nucleotides potentially coding for proteins of 230.7 kDa and 114 kDa respectively. Comparison of the RNA 1 sequence of BPVF‐IND with that of BPVF from Brazil (BPVF‐ BR‐PA) and China (BPVF‐ ZYP‐1) revealed an identity of 95% and 90%, respectively, while RNA 2 showed an identity of 96% and 90%. The phylogenetic analysis of the Pro‐Pol region of RNA 1 and coat protein region of RNA 2 revealed close clustering of all three BPVF isolates well separated from other species of the genus, Fabavirus. Diagnostics assays based on the RT‐PCR and RT‐recombinase polymerase amplification (RT‐RPA) were developed for the sensitive detection of the virus that will help in the identification and propagation of virus‐free black pepper plants.

First report of pepper yellow leaf curl Thailand virus infecting hot chili in central Vietnam and Laos.

Hot chili pepper (Capsicum annuum) cultivation has been on the rise in South East Asia to meet export demands. In Thailand, the top chili exporter in South East Asia, chili production has been severely hampered by pepper yellow leaf curl disease (YLCD) caused by the begomovirus pepper yellow leaf curl Thailand virus (PepYLCThV) (Chiemsombat et al., 2018; Suwor et al., 2021). In the neighbouring countries of Laos and Vietnam, a limited survey of chili fields (200 plants in total) in Savannakhet (Savannakhet University campus, n = 150), Laos and Quang Nam province (Ka Dang commune, Dong Giang district, n = 50), central Vietnam in 2023 led to the finding of eight plants (5 in Laos and 3 in Vietnam) exhibiting YLCD-like symptoms, which included bright yellow color in young leaves and leaf curl and mosaic chlorosis in mature leaves (Fig. S1). Total DNA was extracted from leaves of two symptomatic plants (one from Savannakhet and one from Quang Nam) using a cetyltrimethylammonium bromide-based DNA extraction protocol (Doyle & Doyle, 1987; Nguyen et al., 2023). Next, PCR were performed using newly designed PepYLCThV-specific primers based on PepYLCThV sequences in GenBank (Table 1). PCR products of expected sizes were observed in samples with disease symptoms, but not from DNA extracted from C. annuum (cv. VA.99999) grown at the Institute of Biotechnology in Thua Thien Hue, Vietnam (Fig. S2). The amplicons were Sanger sequenced (Apical Scientific, Selangor, Malaysia) and the complete bipartite genome sequence of two isolates ('Sava01' from Laos and 'QNam01' from Vietnam) were obtained. The sequences of the DNA-A component from isolates 'Sava01' (GenBank PP437580) and 'QNam01' (GenBank PP437581) exhibited the highest sequence identity of 99.2% and 94.7% with the PepYLCThV isolate 'ChiangDaoS1' (GenBank OM677627), respectively (Table 2). Conversely, the sequences of the DNA-B component from the isolates 'Sava01' (GenBank PP437579) and 'QNam01' (GenBank PP437582) exhibited the highest similarity of 91.8% and 90.9% with the PepYLCThV isolate 'KKN601' (GenBank MW715820), respectively (Table 2). These results confirmed the presence of PepYLCThV in hot chili pepper plants exhibiting YLCD-like symptoms in central Vietnam and Laos. Infectious clones of PepYLCThV DNA-A and DNA-B (isolate 'QNam01') were created based on the pLX-AS vector as described by Pasin (2022), and transformed into Agrobacterium tumefaciens EHA105. The resulting bacteria were cultured in LB broth containing rifampicin (25 μg/mL) and kanamycin (50 μg/mL) at 28°C and used for agroinoculation of Nicotiana benthamiana (n = 6) and C. annuum (cv. VA.99999, n = 6) (4-6 leaf plants) as described by Pasin (2022). In all N. benthamiana plants, agroinoculation with both DNA-A and DNA-B infectious clones caused stunted growth, severe leaf curl, with yellow and white patches 21 days post inoculation (Fig. S3). In C. annuum plants, symptom expression, which included leaf curl and stunted leaves with yellow mosaic patterns, was observed in two out of six inoculated plants six weeks postinoculation (Fig. S3). PCR assays confirmed the presence of PepYLCThV DNA in N. benthamiana and C. annuum symptomatic leaves (Fig. S4). To our knowledge, this is the first report of pepper yellow leaf curl Thailand virus in hot chili pepper in Laos and central Vietnam. Appropriate containment and management strategies should be developed and implemented to control the spread of this disease in hot chili pepper crops in both countries.

CLASSIFICATION OF FOCUSES AND MECHANICAL TRANSMISSION OF PLANT VIRUSES

Currently, as a result of the development of many lands, the primary virus foci have decreased. As a result, new relationships between cultivated and wild plants, pathogens and vectors have emerged. To some extent, these relations are characterized by the conceptof natural foci. Because some viruses specialize in a narrow range of plants, they do not spread at all in natural foci. Therefore, studying both theoretical and practical aspects of work in this direction with the help of new, modern methods and technologies is one of the urgent tasks before us in the near future. To date, there is information on several characteristics of all studied tomato, tobacco, turnip, rapeseed, radish, potato, alfalfa, cotton, corn, and bell pepper viruses in Uzbekistan. But thereis no information about their natural foci and groups, and how they slowly infect cultivated plants and the emergence of new virus foci, and they have not been studied until now. Taking this into account, we can identify the natural foci of some viruses studied in Uzbekistan and see the ways of their transmission, especially mechanical transmission.

Elucidating the nature of seed-borne transmission of tomato brown rugose fruit virus in tomato, bell pepper, and eggplant

Elucidating the nature of seed-borne transmission of tomato brown rugose fruit virus in tomato, bell pepper, and eggplant

Serological detection of important pepper viruses and characterisation of pepper mild mottle virus in Saudi Arabia

Serological detection of important pepper viruses and characterisation of pepper mild mottle virus in Saudi Arabia

First report of lettuce ring necrosis virus in chili pepper and tomato in Belgium and The Netherlands.

Lettuce ring necrosis virus (LRNV), genus Ophiovirus, was detected by the Netherlands Institute for Vectors, Invasive plants and Plant health (NIVIP) in June and November of 2021 in two samples of chili pepper fruits (Capsicum spp.), both in mixed infection with other viruses. The first sample originated from a production site in Belgium (Sample ID: 40009704) and the second from a production site in the Netherlands (Sample ID: 41115269). One of the fruits of 40009704 showed a light purple circular pattern, while fruits from 41115269 showed colored (ring)spots. The samples were analyzed using Illumina sequencing on a NovaSeq 6000 platform (PE 150) as described previously (Hammond et al., 2021), obtaining 39.9M and 22.8M total reads for 40009704 and 41115269. The corresponding sequence read archives (SRA) were deposited in the NCBI SRA database under BioProject accession number PRJNA917231. From both samples, the nearly complete genome of LRNV (RNA1-4) was obtained and deposited in GenBank (40009704, OQ160823- OQ160826 (7616, 1799, 1502, 1382 nt, mapped reads: 40K, 12K, 114K, 12K , average read coverage (ARC): 0.8K, 0.9K, 11.3K and 1.1K); 41115269, OQ160827- OQ160830 (7616, 1801, 1518, 1389 nt, mapped reads: 112K, 7K, 357K, 55K reads, ARC: 2.2K, 0.6K, 34K and 5.8K)). The shared sequence identities with the Genbank reference sequence of LRNV (NC_006051-NC_006051) were 99.2 and 99.2% (RNA1), 99.1 and 99.1% (RNA2), 98.3 and 98.8% (RNA3), 99.0 and 98.9% (RNA4) for 40009704 and 41115269 respectively. The shared sequence identities between 40009704 and 41115269 were 99.9 (RNA1), 99.0 (RNA2), 99.1 (RNA3) and 99.5% (RNA4). In addition to LRNV, the ophiovirus ranunculus white mottle virus (RWMV) was detected in both samples (OQ160831-OQ160834; OQ160835-OQ160838), while the tobamovirus pepper mild mottle virus (PMMoV) was present in the fruits of 41115269 (OQ160839). Since RWMV has been associated with leaf symptoms in pepper (Gambley et al., 2019; Rivarez et al., 2022) and the colored (ring)spots of 41115269 were very similar to reported symptoms of PMMoV-infected pepper fruits (Martínez-Ochoa et al., 2003), it remains unclear whether LRNV contributed to the observed symptoms. Additionally, LRNV was detected in tomato (Solanum lycopersicum) in Belgium in 2020. In the frame of a metagenomic survey using Virion-Associated Nucleic Acids (VANA)-based protocol (Maclot et al., 2021) on a Nextseq 500 platform (PE 150), partial genome sequences of LRNV were detected in two pools of tomato plants. One pool was made of 44 asymptomatic cultivars from a non-commercial grower (one sample per cultivar) yielding 118K total reads of which 84, 59, 335, and 18 reads mapped on RNA1, 2, 3, and 4, covering 35%, 69%, 100% and 55% of the genome, respectively. The other pool consisted of 15 plants from one cultivar from a production site yielding 3.1M total reads of which 6 and 5 reads mapped on RNA3 and 4, respectively. The detection of LRNV was confirmed for both pooled samples using the real-time RT-PCR method, targeting the CP gene, as described by Maachi et al. (2021). To our knowledge this is the first report of LRNV in pepper anywhere in the world. Additionally, although the disease lettuce ring necrosis in lettuce (Lactuca sativa) has been described in Belgium and the Netherlands before the causal agent was identified (Bos & Huijberts, 1996), this is the first official report of this virus in Belgium and the Netherlands. This publication resulted from pre-publication data sharing of sequences and biological data among plant virologists to provide more context to two independent findings (Hammond et al., 2021).

Co-infection of tomato brown rugose fruit virus and tomato spotted wilt virus in pepper from Iran

Co-infection of tomato brown rugose fruit virus and tomato spotted wilt virus in pepper from Iran

Distribution and identification of main Viruses Infecting Pepper in Qinghai.

From 2019 to 2021, pepper viruses were investigated in pepper planting areas and collected a total of 333 samples were in Qinghai (The central district, Datong, Huangzhong in Xining; Ledu district, Pingan, Huzhu, Minhe in Haidong, and Jianzha in Huangnan). RT-PCR and molecular cloning were conducted for virus detection in 333 suspected viral samples, the results revealed that viruses infecting pepper mainly included 11 capsicum viruses. Tomato spotted wilt tospovirus （TSWV）has the highest detection rate (36%) in Datong County, and Pepper cryptic virus 1 (PCV1) has the highest detection rate (57%) in Huangzhong County. In the Haidong, 86.3% of the peppers were Broad bean wilt virus 2（BBWV2）, virus-infected Pepper cryptic virus 2 (PCV2), TSWV and Cucumber mosaic virus （CMV） were detected in Xunhua, among which PCV1 and CMV had the highest detection rate (30.4%); PCV1, TSWV, and PCV2 were detected in Ledu and PCV2 had the highest detection rate (50%). There were 17 kinds of co-infection and the co-infection of two viruses occurred often. There were only 5 kinds of co-infection of three. Combined infection contained PCV1 and TMV was the most common. The distribution and species of pepper viruses from the pepper planting areas were clarified and it laid the foundation for preventing and controlling pepper viruses across Qinghai province.

First report of chickpea chlorotic dwarf virus in pepper in Tunisia and in Mediterranean countries

First report of chickpea chlorotic dwarf virus in pepper in Tunisia and in Mediterranean countries

First report of Tomato bushy stunt virus naturally infecting sugar beet in the United States.

Sugar beet (Beta vulgaris L.) is an important crop grown for its sucrose content used in sugar production around the world. Tomato bushy stunt virus (TBSV) is an RNA virus that belongs to the Tombusvirus genus of the family Tombusviridae (Hearne et al., 1990). The virus was first isolated from tomato, and it is known to infect a wide range of plants (Smith, 1935; Martelli et al., 1988; Hafez et al., 2010). In 1980, a natural infection of TBSV was reported in sugar beet leaves with chlorotic and necrotic ring spots and line pattern symptoms based on serological affinity to TBSV anti-sera in Czechoslovakia (Novak and Lanzova, 1980). In March 2021, sugarbeet plants showing stunted and bushy growth with yellowing and necrotic leaves were observed in a production field in the Imperial Valley of California. Harvested roots exhibited stunted and abnormal growth compared to roots from healthy plants (sFig. 1A). These symptoms prompted a screen for potential infection by TBSV. Root-tissue harvested from the symptomatic sugar beet was initially screened using a TBSV double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA; Agdia, Inc., Elkhart, IN), which reacted positive for TBSV. To obtain the full-length sequence of TBSV and potentially other viruses in the sample, total RNA isolated using the RNeasy Plant Mini Kit (Qiagen, Valencia, CA) from the root-tissue was subjected to high-throughput sequencing (HTS). Libraries were prepared using the TruSeq Stranded Total RNA Library Prep kit (Illumina, San Diego, CA) and sequenced using Illumina NovoSeq 6000 paired-end platform (Novogene, Sacramento, CA). A total of 52 million reads were obtained after removing the adapters and reads mapping to the host genome. These high-quality reads were de novo assembled into 75,891 contigs that are larger than 500 base pairs using the SPAdes assembler (Bankevitch et al., 2012; Prjibelski et al., 2020). The resulting contigs were searched for matching sequences to known viruses using the NCBI non-redundant database. A single contig of 4770 nts representing the full-length genome of TBSV was generated (Accession number OP477335), which showed 100% coverage to previously reported TBSV isolates 'statice' (AJ249740.1) and 'nipplefruit' (AY579432.1) with 92.19% and 91.25% nucleotide sequence identities, respectively, and thus confirming the presence of TBSV in sugar beet root-tissue. However, it showed 74% coverage with only 87% nucleotide identity to a previously reported Lettuce necrotic stunt virus (LNSV) from sugar beet, a tombusvirus that was re-classified as Moroccan pepper virus (MPV) due to high degree (>97%) of sequence identity (Obermeier et al., 2001; Wintermantel and Anchieta, 2012; Wintermantel and Hladky, 2013). The coat protein is conserved within species in tombusvirus, and it plays a significant role by providing serological relationships to tombusvirus taxonomy. The coat protein of TBSV-isolate of this study shared 98.45% and 96.91% identities at amino acid level with TBSV 'nipplefruit' (AY579432.1) and TBSV 'statice' (AJ249740.1) isolates, respectively. In contrast, it showed only 61.56% identity with the coat protein of MPV as shown in the phylogenetic tree indicating that the TBSV-isolate reported here is different from MPV (sFig. 2). To confirm the presence of TBSV, reverse-transcription (RT)-PCR was performed using the total RNA isolated from the root-tissue with primers (VR306: 5'-CGCTCACGAGCCCAGCATCCTTGA-3' and VR297: 5'-ACACCGCCACAGGAGCCATGATTG-3') designed based on the HTS data to amplify a portion of the TBSV genome. Sequencing of the RT-PCR product confirmed the presence of TBSV sequence with 99.1% identity to the TBSV-isolate identified in this study. Further, mechanical inoculation of total RNA isolated from the symptomatic sugar beet roots produced local lesions and systemic necrosis symptoms on the leaves of Chenopodium quinoa (sFig. 1B). Sequencing of the amplicon obtained using RT-PCR with primers VR306 and VR297 confirmed the presence of TBSV in C. quinoa. In addition to TBSV, several viral contigs representing Beet necrotic yellow vein virus were identified in the root-tissue indicating mixed infection in the field. To our knowledge, this is the first report that documents the occurrence of TBSV in sugar beet in the United States. Since TBSV is a soil-borne virus, our findings indicate the need for further studies focused on the frequency and coexistence of the TBSV with BNYVV in sugar beet production fields to understand the disease complexity resulting from potential mixed infections.

Detection, characterization, and occurrence of black pepper virus F in black pepper plants in Brazil

Detection, characterization, and occurrence of black pepper virus F in black pepper plants in Brazil

Novel microRNAs associated with the immune response to cucumber mosaic virus in hot pepper (Capsicum annuum L.)

MicroRNAs (miRNAs) are a category of short, highly conserved, noncoding RNAs that modulate various physiological activities correlated with plant growth, stress response, and virus-host interaction. However, the miRNAs associated with cucumber mosaic virus (CMV) resistance in hot pepper (Capsicum annuum L.) remain unexplored. The present work employed small RNA sequencing to compare CMV-infected pepper seedlings with the control seedlings at different time points. The analysis using miRDeep2 software identified 216 known and 34 novel miRNAs from the 12 pepper libraries generated in this study. Further research predicted 3914 targets for these novel miRNAs, of which 3502 were conserved miRNA target genes and 412 were novel miRNA target genes. Functional analysis revealed significant enrichment of these miRNA in ‘plant-pathogen interaction’, ‘ubiquitin-mediated proteolysis’, and ‘metabolic pathways’. Finally, quantitative RT-PCR validated the sRNA sequencing data. These findings set the groundwork for further studies on the CMV resistance mechanisms of pepper.

Relationship between viruliferous Bemisia tabaci population and disease incidence of Pepper yellow leaf curl Indonesia virus in chili pepper

Abstract. Temaja IGRM, Selangga DGW, Phabiola TA, Khalimi K, Listihani L. 2022. Relationship between viruliferous Bemisia tabaci population and disease incidence of Pepper yellow leaf curl Indonesia virus in chili pepper. Biodiversitas 23: 5360-5366. Bemisia tabaci Genn is an important pest in horticulture crops. Until today, B. tabaci has always been found in chili pepper and causes damage. In addition to a direct injury to the chili pepper, it is also the vector of Begomovirus. There is no research till date regarding the relationship between B. tabaci with Begomovirus which caused damage to chili pepper crops. Thus, the aim of this research was to analyze the interaction between B. tabaci population with the disease incidence of Begomovirus on chili peppers crops, as well as the percentage of viruliferous B. tabaci. This research noted B. tabaci population dynamics, disease incidence of pepper yellow leaf curl disease, and the percentage of viruliferous B. tabaci via PCR by using Begomovirus universal primer and DNA analysis confirmation. The highest imago population occurred at 6 WAP with the average density 27.21 imago/yellow sticky card, while the highest nymph population occurred at 8 WAP with the average density of 4.26 nymph/leaf. The high population of B. tabaci nymph and imago caused the incidence of Begomovirus disease to reach 83.07% at 12 WAP. Result showed that high population of B. tabaci accelerated the speed of virus in the field. The confirmation result of Begomovirus in B. tabaci body showed that the virus was Pepper yellow leaf curl Indonesia virus (PYLCIV). The highest homology obtained was between PYLCIV isolates from Sekaan, Bangli with isolates from Bayung Gede, Bangli which ranged from 99.6 to 99.8%. Further phylogenetic analysis showed that PYLCIV isolates from Sekaan, Bali formed a group with the isolate from Bayung Gede, Bangli, which was from a different group with other isolates. This proved that B. tabaci carries and transmits PYLCIV to chili peppers in Bali.

The Virome of Piper nigrum: Identification, Genomic Characterization, Prevalence, and Transmission of Three New Viruses of Black Pepper in China.

Viral diseases are one of the main categories of diseases that cause substantial yield losses in black pepper. Disease symptoms in black pepper are generally complex and are often caused by both known and undescribed viruses. To identify and clarify the etiology of viral diseases in black pepper in Hainan, China, we conducted high-throughput sequencing (HTS) by targeting purified double-stranded RNA (dsRNA) and ribosomal RNA depleted total RNA (rRNA-depleted totRNA). Analysis of the data revealed the presence of one known virus, piper yellow mottle virus (PYMoV), and three newly identified viruses: black pepper virus F (BPVF) in the genus Fabavirus, black pepper virus E (BPVE) in the genus Enamovirus, and black pepper virus B (BPVB) in the genus Badnavirus. The dominant viruses in P. nigrum sampled in Hainan are PYMoV, with an incidence of 100%, followed by BPVF (84%, 133 of 158) and BPVB (66%, 105 of 158). Mechanical inoculation of sap extracts from source plants containing PYMoV, BPVF, and BPVB gave negative results on both herbaceous and woody host plants 60 days postinoculation (dpi). BPVF and PYMoV were successfully transmitted to virus-free seedlings of black pepper through bark grafting, while BPVB was experimentally undetectable up to 150 dpi. Seed transmission experiments showed that no target viruses were present in all 59 germinated seedlings. This study provides information on diagnosis, prevalence, and transmission of black-pepper-associated viruses.

Moroccan pepper virus

This datasheet on Moroccan pepper virus covers Identity, Distribution, Hosts/Species Affected, Further Information.

First report of tomato chlorosis virus in pepper in Greece

First report of tomato chlorosis virus in pepper in Greece

Transcriptome profiling of pepper leaves by RNA-Seq during an incompatible and a compatible pepper-tobamovirus interaction

Upon virus infections, the rapid and comprehensive transcriptional reprogramming in host plant cells is critical to ward off virus attack. To uncover genes and defense pathways that are associated with virus resistance, we carried out the transcriptome-wide Illumina RNA-Seq analysis of pepper leaves harboring the L3 resistance gene at 4, 8, 24 and 48 h post-inoculation (hpi) with two tobamoviruses. Obuda pepper virus (ObPV) inoculation led to hypersensitive reaction (incompatible interaction), while Pepper mild mottle virus (PMMoV) inoculation resulted in a systemic infection without visible symptoms (compatible interaction). ObPV induced robust changes in the pepper transcriptome, whereas PMMoV showed much weaker effects. ObPV markedly suppressed genes related to photosynthesis, carbon fixation and photorespiration. On the other hand, genes associated with energy producing pathways, immune receptors, signaling cascades, transcription factors, pathogenesis-related proteins, enzymes of terpenoid biosynthesis and ethylene metabolism as well as glutathione S-transferases were markedly activated by ObPV. Genes related to photosynthesis and carbon fixation were slightly suppressed also by PMMoV. However, PMMoV did not influence significantly the disease signaling and defense pathways. RNA-Seq results were validated by real-time qPCR for ten pepper genes. Our findings provide a deeper insight into defense mechanisms underlying tobamovirus resistance in pepper.

Application of Reverse Transcription Droplet Digital PCR for Detection and Quantification of Tomato Spotted Wilt Virus

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.

Symptoms of piper yellow mottle virus in black pepper as influenced by temperature and relative humidity

The online version contains supplementary material available at 10.1007/s13337-021-00686-3.