Pepper Yellow Leaf Curl Virus Research Articles

Radio-sensitivity test of gamma irradiation of local chilli pepper seeds (Capsicum annum L.)

Chilli pepper is a strategic horticultural commodity for its economic, nutritional, and medicinal values and is used as a spice in a variety of cuisines all over the world. Induced mutation by gamma ray’s irradiation has been used to increase chilli resistance and quality. The objective of this study was to determine the optimum dose of gamma irradiation in inducing resistance in putative mutation(M1) on chilli pepper seeds. The seeds induced were infected by Pepper Yellow Leaf Curl Virus (PYLCV) and were irradiated with 0, 25, 50, 100,150,200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, and 1000Gy. The plants (M1) were observed for their seed germination, leaf length, leaf width, and plant height. The results indicated that the best LD50 irradiation was 288.269 Gy (y = 82.7847+ 0.0698x + 0.0002x2 + 2.0082x3). The results also revealed that plants irradiated with doses 150, 200, and 250 Gy were selected to be planted in the field.

Effect of Screen House on Disease Severity and Coat Protein Diversity of Begomovirus-infected Capsicum frutescens L. ‘Cempluk’ from Indonesia

Chili can be infected by Begomovirus through whiteflies (Bemisia tabaci) serving as a vector insect. Begomovirus infection causes dwarf plants and yellow curly leaves. The molecular detection of Begomovirus coat protein gene may serve as a preliminary identification of Begomovirus. This study was conducted to observe the differences in the symptom severity of Begomovirus infection in chilies (Capsicum frutescens L. ‘Cempluk’) planted inside and outside a screen house. This study also observed whether or not using a screen house in chili farming affects the diversity of the coat protein of Begomovirus. Symptom observation and sampling were conducted in Madurejo, Prambanan, Sleman. Molecular detection was performed by amplifying the coat protein (CP) gene using the universal primer Krusty and Homer. Results showed 7 plant samples with DNA bands ± 550 bp and confirmed that the plants were positively infected with Begomovirus. The amplified bands were purified and sequenced. The nucleotide sequences were analyzed using BLASTn, followed by phylogenetic analysis using MEGA. Planting chili in the screen house resulted in low disease severity and good crop conditions. The coat protein sequence showed different strains of Begomovirus infected the chili plants inside and outside the screen house. Pepper yellow leaf curl Indonesia virus (PepYLCIV) was found inside the screen house while PepYLCIV [Ageratum] was dominant outside the screen house. Both strains are closely related to other Pepper yellow leaf curl virus (PepYLCV) from various regions in Indonesia. Optical manipulation using an ultraviolet screen or screen house was effective in reducing Begomovirus infection and improving plant performance.

Molecular diversity of Pepper Yellow Leaf Curl Virus (PepYLCV) Infecting Capsicum annuum in West Sumatra

In recent years, Pepper Yellow Leaf Curl Disease (PepYLCD) is one of the most common diseases affecting chili cultivation in Indonesia, including West Sumatra. In 2019, Pepper Yellow Leaf Curl Virus (PepYLCV) damaged chili plants and have lost yields of up to 100%. The controlling of this PepYLCV that has been carried out so far is less effective because the virus often mutates. In 2019, PepYLCV damaged the chili crop and resulted in 100% yield loss. The controls that have been done so far are less effective, especially because the virus mutates frequently. Genome editing is one of the solutions to control the PepYLCV attacks. For that purpose, information of the genome sequence of the PepYLCV is necessary. This study was aimed to obtain the size of the PepYLCV-APWS genome and the differences in its genomic sequence characteristics with other PepYLCV isolates in West Sumatra. The results showed that PepYLCV has a genome size of 2743 bp. This PepYLCV-APWS isolate had molecular diversity with two other isolates from West Sumatra, PepYLCV TDWS and PepYLCV PSSWS respectively 91% and 92%.

Role of the C4 protein PepYLCV in viral symptom determinant: In silico approach

The C4 protein of the monopartite begomovirus pepper yellow leaf curl virus [PepYLCV] plays a major role in the pathogenicity of plant virus infection. Complement gene [C4], in virus, is overlapped with complement gene 1 [C1] or known as Replicase gene [Rep]. The C1 protein is directly involved in virus DNA replication, but not the C4 protein. Recent studies suggested that the C4 is a viral symptom determinant but the molecular mechanism has not been elucidated. In this study, the C4 gene of the novel PepYLCV Alahan Panjang was isolated. To further investigate the role of C4 in symptom determinants, in silico approached was used. Computational modeling of C4 was constructed with homology and ab initio modeling software and the model was checked with Ramachandran Plot. The optimum model of the C4 was used in the surface analysis to predict binding sites and key residues. The mutant structure of the C4 protein and its prospect for CRISPR-Cas9 utilization are discussed.

Optimization of growth regulators to induce callus in chili [Capsicum annuum] cv. Berangkai

The imbalance between demand and yield production causes the price of chili to rise sharply in the market at a particular time. One of the factors driving chili productivity to decrease is the attack of Geminivirus. Geminivirus that attacks chili plant is Pepper Yellow Leaf Curl Virus [PepYLCV]. and causing failure in chili production. Therefore, it is necessary to develop chili varieties that are resistant to PepYLCD by applying a combination strategy of genetic engineering and a tissue culture approach. However, the morphogenetic ability of chilies to regenerate into complete plants is low in developing this strategy. Optimizing growth regulators in the media of callus induction can increase the morphogenetic response of chilies. This research aimed to obtain the optimal composition of callus induction media. The results showed that the use of the media composition of 2.5 mg/L NAA + 2.5 mg/L IAA and 3.5 mg/L 2.4 D + 0.25 mg/L TDZ could initiate callus formation on the eighth day after induction. Both media compositions have a callus growth percentage of about 100%, which has a friable and yellowish-white callus morphology.

Identification of a novel pepper-infecting monopartite begomovirus in China

Three full-length monopartite begomovirus sequences were obtained from two field-collected pepper plants exhibiting severe leaf yellowing disease symptoms in Yunnan province of China. The three full-length viral sequences contain 2,748 nucleotides (nt) and share the highest nt sequence similarity (88.2% identity) with that of malvastrum yellow vein Yunnan virus (MYVYNV). The betasatellite molecules of the two viruses share the highest sequence similarity (99.3% identity) with that of malvastrum yellow vein Yunnan betasatellite (MYVYNB). Based on the current species demarcation criteria for the genus Begomovirus, these three newly identified isolates can be considered members of a novel monopartite Begomovirus species, and we have named this virus "pepper yellow leaf curl virus" (PepYLCV). Phylogenetic analysis showed that PepYLCV clustered with pepper leaf curl Yunnan virus (PepLCYNV). Recombination analysis revealed that PepYLCV is likely to have originated through a recombination event between MYVYNV and tomato leaf curl Yunnan virus (TLCYnV).

Editing of PCNA Gene by CRISPR/Cas9 Technology to Improve the Red Chili Resistance to Yellow Leaf Curl Disease

<p>Yellow leaf curl disease caused by Pepper yellow leaf curl virus (PepYLCV), member of geminiviruses group, is responsible for heavy yield losses for chili pepper production. Resistant genes which can cause immunity to the disease have not been found in germplasm collection. The aim of the research was to edit proliferating cell nuclear antigen (PCNA) gene by using CRISPR/Cas9 technology for developing plant resistance against geminivirus in chili pepper. A CRISPR/Cas9 plasmid cassette construct harboring the guide RNA of PCNA gene was constructed by Golden Gate cloning strategy. The construct was then introduced into chili genome via in planta method using Agrobacterium tumefaciens EHA105. The transformed plants were bioassayed by virus inoculation and confirmed using PCR and DNA sequencing to identify a mutagenesis event in PCNA gene target. The results showed that CRISPR/Cas9 plasmid cassette harboring gRNA of PCNA gene was successfully constructed. In planta transformation using A. tumefaciens vector harboring CRISPR/Cas9-gRNA PCNA construct resulted in 307 and 193 transformed plants from chili var. Lingga and Ciko, respectively. Bioassay by using virus inoculation to the transformed plants obtained 6 and 14 lines of Lingga and Ciko, respectively, which were resistant to geminivirus (no symptom observed). The resistant lines of chili pepper var. Lingga and Ciko were mutated in PCNA gene with one base insertion or deletion mutation types. These results exhibit that the CRISPR/Cas9 genome editing can be used to induce mutant of PCNA gene in chili pepper. Further investigation is necessary to evaluate the selected chili lines resistant to PepYLCV infection.</p>

In silico analysis of PepYLCV-βC1 protein interaction with pepper-SnRK1 for pathogenicity prediction

Pepper yellow leaf curl virus [PepYLCV] is a monopartite begomovirus that is usually associated with a beta satellite which encodes a pathogenicity protein [βC1] responsible for symptom appearance. A recent study revealed that plants overexpressing SnRK1 were delayed for symptom appearance and lower levels of satellite DNA. The current study provided the interaction of PepYLCV BC1 and Pepper SnRK1 protein by using computational approaches including homology modeling and protein-protein docking. The reliability of the 3D model was validated by using the Procheck server. Findings suggest that ubiquitin-associated [UBA] and auto-inhibitory sequence [AIS] domains of Pepper-SnRK1 are involved in the PepYLCV-βC1 interaction. Findings provide computational data support for domain-level interactions to predict the pathogenicity of new monopartite begomoviruses that lack known experimental data.

First Report of Pepper Vein Yellows Virus and Pepper Yellow Leaf Curl Virus Infecting Chilli Pepper (Capsicum annuum) in Malaysia

First Report of Pepper Vein Yellows Virus and Pepper Yellow Leaf Curl Virus Infecting Chilli Pepper (<i>Capsicum annuum</i>) in Malaysia

Genetic variations of EMS-induced chili peppers (Capsicum annuum) cv. Gelora generate geminivirus resistant mutant lines

A mutation breeding program was conducted to improve chili pepper (Capsicum annuum) resistance to Geminivirus caused by Pepper yellow leaf curl virus (PepYLCV). The disease can cause significant yield losses on chili pepper. This study was conducted to enhance genetic variation in pepper cv. Gelora using ethyl methanesulphonate (EMS) to obtain mutant lines resistant to PepYLCV. Exposure to an EMS solution of 0.5% (v/v) for 30 minutes was used for mutagenizing shoot tips to produce the first population (M1). After the treatment, shoot tips were cultured on MS medium to regenerate planlets that were subsequently acclimatized to produce M2 population. A set of 2,955 mutant lines (M2) were screened in a greenhouse by inoculating PepYLCV isolate Segunung using white flies (Bemisia tabaci) as the virus vector. Six weeks after inoculation, the M2 population was examined for symptoms of Geminivirus and was verified for the presence of PepYLCV infection by PCR using specific primer. The greenhouse assay successfully selected 47 lines (1.6%) of M2 mutant population that showed no symptoms and no infection to PepYLCV compared to Gelora and Tanjung-2 varieties. Subsequent field test of M3 mutant lines in Geminivirus endemic area in Lembang, West Bandung, revealed that 15 out of 47 lines showed high resistance to PepYLCV and have good agronomic characters including yield components. A set of primers corresponding to the PepYLCV infection which produced 678 bp in size indicated its good amplification in the susceptible mutant lines, confirming the PepYLCV resistance of 15 selected mutant lines. The resistant mutants were immune to PepYLCV and had potential to be released as improved varieties in the future.

The Effect of Silica (SiO2) to the Severity of Yellow Leaf Curl Disease on Chili Pepper

Yellow leaf curl disease of chili pepper caused by Pepper yellow leaf curl virus (PYLCV) has been reported as an important disease in Java and Bali. Disease severity reached 80−100% and it may cause significant yield losses. In order to reduce the negative impact of synthetic insecticides, silica application was evaluated for its potency to suppress the disease. A greenhouse experiment was conducted using randomly block design with 2 factors: PYLCV isolate (Java and Bali) and silica (SiO2) treatment (with and without). Parameters observed were disease symptoms, incubation period, disease incidence and severity, and total silica level. The symptoms of virus infection in Pelita 8 and Seret cultivars were yellow mosaic, leaf curl, green mosaic, dwarf, and cupping upward or downward. A Specific DNA fragment of 912 bp was successfully amplified from 4 samples. Four sequences were obtained and further analysis showed their highest homology, i.e. 96% and 97% with Pepper yellow leaf curl Indonesia virus-Java (PYLCIV-Java) (JX416180) and PYLCIV-KrthAl (LC381274), respectively. Infection by different virus isolates did not affect disease severity significantly. The application of silica was able to delay symptom development and to suppress the severity of the disease in the range of 16.67−30.33%. Silica application on the soil increased the total content of silica in the plants. However, a further experiment is required to understand the mode of action of silica in inducing plant resistance to the pathogen.

Determination of Endophytic Fungi as Induce Resistance Agent of Chilli Pepper Against Pepper Yellow Leaf Curl Disease

Pepper yellow leaf curl disease caused by Pepper yellow leaf curl virus becomes a major problem on chilli pepper in Indonesia since 2000. Endophytic fungi has the potency to suppress plant diseases by acting as induced resistant agent. The objective of this research was to determine the effect of endophytic fungi application on incidence of yellow leaf curl disease of chilli pepper. Four isolates of endophytic fungi, i.e. Cercospora nicotianae isolate H5, Curvularia sp. isolate H12, Fusarium sp. isolate AC-2.7 and AC-4.5 were applied as seed treatment and leaf spray on 2 chilli varieties, ‘Biola’ and ‘Luwes’. Observations of incubation period showed that delayed symptom occurred on application of Fusarium sp. isolate AC-2.7 and Curvularia sp. isolate H12. Disease incidence reached 100 % in all treatments. Less severe symptom was observed on application of Curvularia sp. isolate H12. Most plants infected by PYLCIV showed obvious symptoms of yellow mosaic, leaf curling and stunting. Plant productivity analysis showed that application of Fusarium sp. isolate AC-2.7 resulted higher fruit weight and this treatment may induce tolerant response of the plants to PYLCIV infection. Initial effort to evaluate endophytic fungi as biocontrol agents for pepper yellow leaf curl disease should be studied further.

Characterization of Pepper leafroll chlorosis virus, a New Polerovirus Causing Yellowing Disease of Bell Pepper in Saudi Arabia.

During the growing seasons of 2014 through 2016, a total of 336 leaf samples from bell pepper (showing leafroll and interveinal yellowing) and arable weeds were collected from Riyadh region, Saudi Arabia. The use of a polerovirus generic reverse transcription (RT)-PCR assay confirmed their presence in the bell pepper samples. Sequencing of the generic amplicon revealed high similarity (87.6 to 98.1% in nt) with four poleroviruses; Tobacco vein distorting virus, Pepper vein yellows virus, Pepper yellows virus, and Pepper yellow leaf curl virus. To further characterize one of these isolates (105D), a larger part of the genome (∼1,300 nt) spanning approximately from the 3' end of ORF2 to the middle of ORF3, was amplified and sequenced. Blasting the resulting sequence revealed the low amino acid and nucleotide identity percentages in the coat protein and movement protein partial genes with viruses deposited in GenBank. Next-generation sequence was used to acquire a larger part of the genome, which resulted in the reconstruction of isolate 105D's partial genome (5,496 nt). Sequence similarity analysis revealed the presence of a divergent polerovirus isolate belonging to a new species that was tentatively named Pepper leafroll chlorosis virus (PeLRCV). Using a specific RT-PCR assay for this isolate confirmed the presence of this new viral species in the symptomatic peppers. Aphid transmission experiments showed that PeLRCV is vectored by Aphis gossypii and that it can infect at least five out of the 15 different plants species tested. Based on our findings, PeLRCV is a new member of genus Polerovirus in the family Luteoviridae.

Insights Into the Etiology of Polerovirus-Induced Pepper Yellows Disease.

The study of an emerging yellows disease of pepper crops (pepper yellows disease [PYD]) in Greece led to the identification of a polerovirus closely related to Pepper vein yellows virus (PeVYV). Recovery of its full genome sequence by next-generation sequencing of small interfering RNAs allowed its characterization as a new poleroviruses, which was provisionally named Pepper yellows virus (PeYV). Transmission experiments revealed its association with the disease. Sequence similarity and phylogenetic analysis highlighted the common ancestry of the three poleroviruses (PeVYV, PeYV, and Pepper yellow leaf curl virus [PYLCV]) currently reported to be associated with PYD, even though significant genetic differences were identified among them, especially in the C-terminal region of P5 and the 3' noncoding region. Most of the differences observed can be attributed to a modular type of evolution, which produces mosaic-like variants giving rise to these different poleroviruses Overall, similar to other polerovirus-related diseases, PYD is caused by at least three species (PeVYV, PeYV, and PYLCV) belonging to this group of closely related pepper-infecting viruses.

Keragaman Cendawan Rizosfer dan Potensinya sebagai Agens Antagonis Fusarium oxysporum Penyebab Penyakit Layu Tanaman Krisan

Virus infection is an important production constraint for soybean. Research was conducted to detect virus infection from soybean samples collected from several locations in Java. Leave samples from 50 plants was taken randomly from each location in Bogor, Cirebon, Bantul, and Ponorogo. Field symptoms was observed and disease incidence was determined based on serological assay using specific antibodies to Cucumber mosaic virus (CMV), Soybean mosaic virus (SMV), Cowpea mild mottle virus (CPMMV), and Bean pod mottle virus (BPMV). Incidence of CMV, SMV, and CPMMV was 72–84%, 14–24%, and 6–8%, respectively; whereas infection of BPMV was not found. Specific viral DNA of CMV, Potyvirus, and Geminivirus was successfully amplified using specific primer for CMV coat protein, universal primer for Potyvirus and Geminivirus, respectively. Nucleotide sequence analysis showed that isolate CMV from soybean has the highest homology (99%) to CMV strain S, Potyvirus isolates has the highest homology (90%) to BCMV isolate Mungbean from China and BCMV strain Blackeye from Vietnam, and Geminivirus isolates has the highest homology (96%) to Pepper yellow leaf curl virus (PYLCV) from Bogor and Java. Phyllogenetic analysis showed that CMV strain S formed

Characterization of the Complete Genome of a Novel Polerovirus Infecting Sauropus androgynus in Thailand

AbstractLeaf samples from Thailand of Sauropus androgynus (L.) Merr. plants presenting leaf yellowing symptoms were screened by reverse transcription polymerase chain reaction for the presence of polerovirus infection. In five of eight samples, a polerovirus was detected, and in four of these five polerovirus‐positive samples, a begomovirus infection had been detected in a previous study. The complete polerovirus genome sequence was determined from the sample which was not also infected with a begomovirus. Analysis of the sequence revealed the typical genome organization of a polerovirus. The highest nucleotide sequence identity to any other polerovirus species sequence in GenBank was 49% to pepper yellow leaf curl virus (PYLCV), and the highest amino acid sequence identity of all deduced protein sequences was 70% with the coat protein of PYLCV. Based on these findings, we propose this novel polerovirus species be named Sauropus yellowing virus (SaYV).

Keparahan Penyakit Daun Keriting Kuning dan Pertumbuhan Populasi Kutukebul pada Beberapa Genotipe Cabai

Incidence of yellow leaf curl disease on chili pepper is very common in Indonesia and becomes major production constrain. The causal agent, Pepper yellow leaf curl virus (PYLCV), is only transmitted by insect vector, i.e. whitefly ( Bemisia tabaci ). Research was conducted to determine response of 6 chili pepper genotypes [Meteor, Rimbun, Tornado, F1(12X14), IPBC12, and 35C2] against infection of PYLCV and population growth of whitefly on each genotypes. Transmission of PYLCV to chili pepper genotypes was done using whitefly. Whitefly was maintained on each chili pepper genotypes to evaluate its population growth. Genotype IPBC12 was resistant to PYLCV having disease severity 0–9.2% and showed mild symptom. Genotypes Rimbun, Meteor, Tornado, F1(12X14), and 35C2 were susceptible having disease severity >20% and showed severe symptom. Resistance of IPBC12 might be correlated with the growth of whitefly on the genotype. The amount of whitefly eggs and its successful rate to become adult was relatively lower in IPBC12 than those in other genotypes. Genotype IPBC12 might be considered as resistance source in developing resistant variety of chili pepper to PYLCV.

First Report of Pepper vein yellows virus Infecting Hot Pepper in Sudan.

In two successive winters (2009 and 2010), 14 hot pepper (Capsicum annuum) samples showing unusual symptoms were surveyed in permanently irrigated seasonal vegetable gardens along the Blue Nile in central Sudan (specifically in Gezira State). Symptoms included leaf curling, leaf deformation, reduced leaf size, leaf puckering, interveinal yellowing, vein clearing, or yellow patches. Total RNA was extracted from symptomatic leaves and analyzed by reverse transcription (RT)-PCR with degenerate primer pairs that amplify different viral species within the family Luteoviridae (1). Amplification of a 340-bp fragment of the coat protein gene (CP) was obtained in all the collected samples analyzed. The amplified fragments were purified and sequenced (Accession Nos. KC685313 to 26), showing 99, 97, and 95 to 99% nucleotide identities to Pepper yellows virus (PYV, accession no. FN600344 from Turkey), Pepper vein yellows virus (PeVYV, AB594828 from Japan) and Pepper yellow leaf curl virus (PYLCV, HM439608 from Israel), respectively. These three viruses belong to the genus Polerovirus and are considered synonyms of the same virus species PeVYV described with those names in different countries (3). Two samples were also tested by RT-PCR with the general Polerovirus primer pair Pol-G-F and Pol-G-R, which amplified a 1.1-kb product spanning the 3' half of the RNA-dependent RNA polymerase (RdRp) to the 5' half of CP and movement protein (2). The amplified fragments (KC692834 and KC692833) showed 97, 96, and 95% nt identity with PYV (FN600344), PeVYV (JX427533), and PYLCV (HM439608), respectively. The presence of the recently described Polerovirus PeVYV is the first report of detection in pepper in Sudan. PeVYV has recently been identified in seven other countries (India, Indonesia, Mali, the Philippines, Spain, Taiwan, and Thailand) and on one new host, Solanum nigrum, which suggests this new Polerovirus species poses a potentially wide geographical distribution and a global threat for pepper crops (3,4).

First Report of Pepper vein yellows virus Infecting Sweet Pepper in Spain.

In November 2012, unusual symptoms were observed in plants of sweet pepper (Capsicum annuum L.) grown in commercial greenhouses of Almería Province, southeastern Spain. Symptoms included interveinal yellowing, upward leaf curling, and internode shortening, and were more evident in the upper part of the plant. Abnormal ripening of fruits was observed in symptomatic plants, with fruits remaining orange in the red varieties and yellow in the orange varieties, thus reducing their marketability. During December 2012 and January 2013, severe outbreaks of this disease syndrome occurred, with many greenhouses exhibiting almost 100% incidence. The symptoms observed were similar to those reported for isolates of Pepper vein yellows virus (PeVYV, genus Polerovirus, family Luteoviridae) (previously also named Pepper yellow leaf curl virus [PYLCV] and Pepper yellows virus [PYV]) (2,4). Twenty five symptomatic leaf and/or fruit samples (some of them supplied by Zeraim Ibérica, S.A.), each from a different greenhouse, were analyzed and all reacted positively in double-antibody sandwich-ELISA with an antiserum against the polerovirus Cucurbit aphid-borne yellows virus (CABYV) (Sediag, Longvic, France), known to cross-react with PeVYV (2). Total RNA was extracted by TRIsure reagent (Bioline, London, United Kingdom) from symptomatic leaves and analyzed by reverse transcription (RT)-PCR with primers Pol-G-F (5'-GAYTGCTCYGGYTTYGACTGGAG-3') and Pol-G-R (5'-GATYTTATAYTCATGGTAGGCCTTGAG-3') designed for universal detection of poleroviruses by amplifying the RNA-dependent RNA polymerase (RdRp) and coat protein (CP) partial genes (3). DNA fragments of the expected size (1.1 kbp) were amplified supporting a polerovirus infection in all the analyzed samples. The PCR product obtained from one sample (Almería-1) was extracted from agarose gel with a QIAquick gel extraction kit (Qiagen, Hilden, Germany), cloned in pGEM-T Easy vector (Promega, Madison, WI), and one clone was sequenced (Macrogen Inc., Seoul, South Korea). The PCR products amplified from three other samples (2-13, 7-13, and 8-13) were directly sequenced. The nucleotide identity between the amplified fragments (GenBank Accession Nos. KC769487, KC839992 to 94), calculated after alignment with ClustalW, was 99.7 to 100%. The highest nucleotide identity of the Spanish sequences was with a PeVYV isolate from Turkey (FN600344, named as PYV) (98.5 to 98.7%). The spread of PeVYV in Spain is additional evidence of the emergence of this virus as a global threat for pepper crops after its first detection in Japan in 1995 and recent reports from the Mediterranean Basin (1,2).

The Complete Genomic Sequence of Pepper Yellow Leaf Curl Virus (PYLCV) and Its Implications for Our Understanding of Evolution Dynamics in the Genus Polerovirus

We determined the complete sequence and organization of the genome of a putative member of the genus Polerovirus tentatively named Pepper yellow leaf curl virus (PYLCV). PYLCV has a wider host range than Tobacco vein-distorting virus (TVDV) and has a close serological relationship with Cucurbit aphid-borne yellows virus (CABYV) (both poleroviruses). The extracted viral RNA was subjected to SOLiD next-generation sequence analysis and used as a template for reverse transcription synthesis, which was followed by PCR amplification. The ssRNA genome of PYLCV includes 6,028 nucleotides encoding six open reading frames (ORFs), which is typical of the genus Polerovirus. Comparisons of the deduced amino acid sequences of the PYLCV ORFs 2-4 and ORF5, indicate that there are high levels of similarity between these sequences to ORFs 2-4 of TVDV (84-93%) and to ORF5 of CABYV (87%). Both PYLCV and Pepper vein yellowing virus (PeVYV) contain sequences that point to a common ancestral polerovirus. The recombination breakpoint which is located at CABYV ORF3, which encodes the viral coat protein (CP), may explain the CABYV-like sequences found in the genomes of the pepper infecting viruses PYLCV and PeVYV. Two additional regions unique to PYLCV (PY1 and PY2) were identified between nucleotides 4,962 and 5,061 (ORF 5) and between positions 5,866 and 6,028 in the 3' NCR. Sequence analysis of the pepper-infecting PeVYV revealed three unique regions (Pe1-Pe3) with no similarity to other members of the genus Polerovirus. Genomic analyses of PYLCV and PeVYV suggest that the speciation of these viruses occurred through putative recombination event(s) between poleroviruses co-infecting a common host(s), resulting in the emergence of PYLCV, a novel pathogen with a wider host range.