Pepper Yellow Leaf Curl Indonesia Virus Research Articles

Molecular Detection and Identification of Begomovirus Infecting Cucumber (Cucumis sativus) in Terengganu, Malaysia

The genus Begomovirus from the family Geminiviridae is responsible for causing significant economic losses to many important horticultural crops, including cucumber (Cucumis sativus L.). Begomovirus infection during the early stages of plant growth can lead to complete yield loss. Hence, the identification of begomovirus species is important to design a precise resistant breeding strategy. This study aims to detect the presence of begomovirus in typical symptomatic cucumber leaves, identify the species of begomovirus present, and investigate the evolutionary relationships with other reported begomoviruses using phylogenetic analysis. Leaf samples from symptomatic cucumber plants were collected from the Green World Genetics (GWG) research station and a farm in Lembah Bidong, Rhu Tapai, Setiu, Terengganu. To detect the presence of begomovirus, PCR was carried out using universal primers targeting DNA-A, DNA-B, and betasatellite regions. DNA-A and betasatellite fragments were amplified, but not DNA-B. The amplified partial sequences of DNA-A were then analysed and compared with other begomovirus sequences in the GenBank database managed by the National Centre for Biotechnology Information (NCBI). The newly isolated DNA-A sequence from cucumber was 100% identical to the tomato leaf curl New Delhi virus (ToLCNDV). The phylogenetic tree was divided into two groups: group A, consisting of the newly isolated DNA-A sequence from cucumber, ToLCNDV, followed by squash leaf curl China virus (SLCCNV) and a monopartite begomovirus Ageratum yellow vein virus (AYVV); and group B, consisting of tomato yellow leaf curl Kanchanaburi virus (TYLCKaV), pepper yellow leaf curl Indonesia virus (PepYLCIV), and pepper yellow leaf curl Aceh virus (PepYLCAV). For the first time in cucumber, betasatellite is reported in association with ToLCNDV, a bipartite old-world begomovirus. This study provides a basis for the selection and breeding of begomovirus-resistant cucumber varieties in the future.

Updates on hosts and distribution of pepper yellow leaf curl Indonesia virus and squash leaf curl China virus in Central Java Province, Indonesia

Chili pepper, tomato, and squash cultivated in Magelang Regency, Central Java Province, Indonesia showed severe viral symptoms. Three samples were taken then molecularly tested against begomovirus, potyvirus, tobamovirus, and polerovirus. However, PCR test confirmed only begomovirus infections. BLAST analysis concluded that the chili pepper and tomato isolates were pepper yellow leaf curl Indonesia virus (PepYLCIV) while the squash isolate was squash leaf curl China virus (SLCCNV). The 552 bp partial AV1 gene sequences of the three isolates were given NCBI GenBank acc nos. OR924278-80. PepYLCIV OR924279 and OR924280 formed a subgroup with LC542629 from Bali in the phylogenetic tree constructed using MEGA11, and shared 95.8 – 96.7% identities at nucleotide (nt) and 98.4 – 99.5% at amino acid (aa) levels according to Sequence Demarcation Tool v1.2 software. Meanwhile, SLCCNV OR924278 was clustered, and shared 95.8 – 96.7% nt and 98.4 – 99.5% aa identities with three Malaysian isolates (MW248685, MW248687, and MW248689). Different plant species inoculated with SLCCNV OR924278 remained symptomless up to four weeks observation, suggesting that the isolate is not mechanically transmissible. This study contributed additional knowledge on molecular variation while expanding hosts and distribution of PepYLCIV and SLCCNV in Central Java Province.

Begomoviruses on two chili types in Southeast Sulawesi Indonesia: variation of symptom severity assessment and DNA-betasatellite identification

The association of viral satellite DNA with Begomoviruses influences symptom expression in infected plants. Normalized Difference Vegetation Index (NDVI) is an image processing method used to assess plant health based on the plant’s ability to absorb sunlight for photosynthesis. Therefore, this study aims to assess symptom severity based on symptom variation and NDVI, as well as to detect and identify the presence of beta-satellite DNA associated with chili plants. The study was conducted in North Kolaka Regency, Southeast Sulawesi Province, Indonesia. It involved observations and image recording of symptom variations in the sampled cayenne and big red chili plants, followed by the detection of beta-satellite DNA in the samples using the polymerase chain reaction (PCR). The results confirmed the presence of non-coding satellite DNA associated with the Pepper yellow leaf curl Indonesia virus (PepYLCIV) in all severe, mild, or asymptomatic plant samples. In the phylogenetic tree, the non-coding satellite DNA isolates from Southeast Sulawesi are included in the betasatellite group and exhibit different genetic characteristics from other isolates available in the GenBank database. The cayenne chili with severe symptoms had lower NDVI values than the mild and asymptomatic categories, indicating that this type of chili with severe symptoms had a lower ability to absorb light. Further studies are needed to characterize the alpha-satellite type in the Southeast Sulawesi region for potential use in cross-protection mechanisms against plant virus infections.

Effect of several reduced-risk insecticides on the population of Bemisia tabaci Genn. and incidence of pepper yellow leaf curl Indonesia virus (PepYLCIV) on chili plants

Tobacco whitefly, Bemisia tabaci Genn. can directly, and indirectly damage chili plants by sucking the plant sap and transmitting Pepper yellow leaf curl Indonesia virus (PepYLCIV), respectively. Farmers control PepYLCIV by using synthetic insecticides with 2-3 applications a week to suppress the vector population. The intensive use of insecticide raises concern about potential detrimental effects on the environment and non-target organisms. An alternative control measure for B. tabaci is the use of reduced-risk insecticides that are effective but safer. Thus, the study aimed to determine the effectiveness of various reduced-risk insecticides in reducing the whitefly population and PepYLCIV incidence. This experiment consisted of 12 treatments using insecticides of abamectin, azadiractin, imidacloprid, deltamethrin, spinosad, and water (control), applied once and twice a week. The results showed that the low-risk insecticides had no significant effect on the numbers of adults and nymphs of B. tabaci and the PepYLCIV incidence. Imidacloprid had significantly lower egg number and PepYLCIV incidence than the control and the other insecticide treatments. Our results also showed that B. tabaci populations were low throughout the season but the incidences of PepYLCIV were relatively high. This indicated a possibility that PepYLCIV is seed-borne.

Current Status and Complexity of Three Begomovirus Species in Pepper Plants in Lowlands and Highlands in Java Island, Indonesia.

Three primary species from the Begomovirus genus, Pepper yellow leaf curl Indonesia virus (PepYLCIV), Tomato yellow leaf curl Kanchanaburi virus (TYLCKaV), and Tomato leaf curl New Delhi virus (ToLCNDV), are suspected of spreading throughout pepper production centers, and plants are infected by a single species or a combination of two or three species. This study was conducted to provide complete information about the symptoms, incidence and severity, whitefly biotypes, as well as the dominance status of the three Begomovirus species in pepper-producing areas in Java. A DNA analysis was carried out on leaf samples to identify Begomovirus species and biotypes of B. tabaci collected from 18 areas (16 districts) in lowlands (<400 m asl) and highlands (>700 m asl). The DNA analysis showed that B. tabaci biotype B was the most commonly detected in all locations compared to the A, AN, and Q biotypes. The incidence of begomovirus infection was at a high level, 93% and 88.78% in the lowlands and highlands, respectively. However, the severity of begomovirus infection was significantly higher in the lowlands (54.50%) than in the highlands (38.11%). A single infection of PepYLCIV was most dominant in all locations sampled and caused severe infection, followed by a mixed infection with TYLCKaV. Therefore, the current status of begomovirus infection, especially PepYLCIV, can provide advice to farmers using more tolerant and resistant varieties as well as a breeding strategy for resistant pepper varieties.

DETEKSI MOLEKULER DAN ANALISIS GENETIK BEGOMOVIRUS PADA TANAMAN CABAI DI DESA PEMATANG DONOK

The chili cultivation center in Bengkulu Province, which is located in Pematang Donok Village, Kepahiang Regency, has found many symptoms of yellow curly leaf disease, but there have been no reports of viral species that infect the chili plantations. Sampling was done by purposive sampling method based on the symptoms of chili plants infected with Begomovirus. Virus detection using polymerase chain reaction (PCR) method using general primer Begomovirus (SPG 1/2). The PCR product was sent to First Base, Malaysia for DNA sequencing. Sequencing data were analyzed using MEGA 6 (Molecular Evolutionary Genetics Analysis) software for phylogenetic tree construction. Based on field observations, the incidence of disease ranged from 96.4%-100% and the whitefly vector insect (Bemisia tabaci) was found. PCR using general primers Begomovirus obtained DNA bands measuring 912 bp according to the primary target. Based on the Blastn results, the nucleotide sequences of 3 Begomovirus samples from Pematang Donok Village had nucleotide similarities with the Pepper yellow leaf curl Indonesia virus (PYLCIV) isolates from Bali and Java contained in the GenBank database, with a nucleotide similarity value of 91.77%-98.99%.

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.

PepYLCIV and PepYLCAV resistance gene Pepy-2 encodes DFDGD-Class RNA-dependent RNA polymerase in Capsicum.

A begomovirus resistance gene Pepy-2 encoding the DFDGD-Class RNA-dependent RNA polymerase 3a was identified in pepper (C. annuum) through the forward and reverse genetic analyses. In several countries throughout the world, the whitefly-transmitted begomovirus causes massive yield losses in pepper (Capsicum spp.) production. Although introgression of the genetic resistance against begomovirus to commercial cultivars is strongly required, the recently discovered recessive resistance gene pepy-1, which encodes the messenger RNA surveillance factor Pelota, is the only begomovirus resistance gene identified in Capsicum so far. In this study, we fine-mapped another begomovirus resistance gene from PG1-1 (C. annuum), which is resistant to pepper yellow leaf curl Indonesia virus (PepYLCIV) and pepper yellow leaf curl Aceh virus (PepYLCAV), to further speed up the marker-assisted breeding of begomovirus resistance in peppers. A single dominant locus, Pepy-2, conferring resistance against PepYLCIV in PG1-1 was identified on chromosome 7 by screening recombinants from the F2 and F3 segregating populations derived from a cross between PG1-1 and begomovirus susceptible SCM334. In the target region spanning 722kb, a strong candidate gene, the RNA-dependent RNA polymerase 3a (CaRDR3a), was identified. The whole-genome and transcriptome sequences of PG1-1 and SCM334 revealed a single Guanine (G) deletion in CaRDR3a first exon, causing a frameshift resulting in loss-of-function in SCM334. In addition, multiple loss-of-function alleles of CaRDR3a were identified in the reference sequences of C. annuum, C. chinense, and C. baccatum in the public database. Furthermore, virus-induced gene silencing of CaRDR3a in PG1-1 resulted in the loss of resistance against PepYLCIV. PG1-1 and the DNA marker developed in this study will be useful to breeders using Pepy-2 in their breeding programs.

Distribution and Identification of Pepper yellow leaf curl Indonesia virus Infecting Chili Pepper in Bali Island

Yellow leaf curl disease in chili pepper has been reported in Bali Island since the early 2012. Research was conducted to identify the virus causing this disease and disease distribution in Bali. Field survey was carried out to observe disease intensity and to collect field samples from several chili pepper growing areas in Bali (Karangasem, Bangli, Tabanan, and Gianyar). Begomovirus identification from field samples was then conducted by polymerase chain reaction method using universal primers SPG1/SPG2, followed by an analysis of the amplified target DNA sequences. The incidence of pepper yellow leaf curl disease reached 100% at all sites and disease severity reached 18%−87%. Begomovirus specific DNA fragment measuring 912 bp was successfully amplified from 12 field samples. Sequence analysis of DNA fragments showed the highest homology with Pepper yellow leaf curl Indonesia virus (PYLCIV). Further phylogenetic analysis confirmed the relationship between PYLCIV isolates from Bali and various PYLCIV isolates from Indonesia.

RECOMBINANT ANTIBODY PRODUCTION BY CLONING OF Pepper yellow leaf curl Indonesia virus (PepYLCIV) COAT PROTEIN GENE

Pepper yellow leaf curl Indonesia virus (PepYLCIV) is an important pathogen on chili cultivation and is transmitted through the seed. Serological tests are sensitive, accurate, efficient and it has been widely used for the detection of seed-transmitted plant viruses. This study aimed to produce PepYLCIV recombinant protein as a material to produce recombinant antibodies PepYLCIV. DNA was extracted from infected chili leaves collected from Congkrang, Muntilan, Central Java verified using primer PepYLCIV-BamHI and PepYLCIV-EcoRI and produced an amplicon at 840 bp. The amplified fragments were cloned into the pET32a then transformed to Escherichia coli BL21. The percentage of nucleotide sequence identity and sequence of amino acid, PepYLCIV CK-6 isolates had the highest similarity of nucleotide and amino acid sequences to of chili isolates from Bandung. The expressed recombinant protein was obtained with IPTG concentration 0,5 mM and harvested at 6 hours after IPTG induction. SDS PAGE analysis of the recombinant plasmid Begomovirus CK-6 showed that the coat protein size was about 29 kDa. Immunization was carried out on rabbits by injecting 150 µg of recombinant protein 4 times with an interval of 1 week to produce crude antiserum and pure antiserum capable of detecting PepYLCIV in chili and Ageratum conyzoides using I-ELISA and DIBA tests.

Growth and yield response of a local pepper (Capsicum annuum L.) accession to begomoviral caused disease in the medium elevation land

The experiment aimed to evaluate resistance of a local pepper accession to begomovirus caused disease which is annually observed in pepper cultivation in Aceh, Indonesia. The evaluation was conducted by assessing the growth and yield response of the pepper plants in the median elevation. The field experimental was conducted in Agricultural Staff Training Center (BLPP) Saree and Horticultural Laboratory of Syiah Kuala University from December 2018 to August 2019. Purpose sampling method was established to for plant selection devided into two clusters. The first cluster of 930 plants was evaluated for typical symptom of begomovirus caused disease from 15 to 135 days post transplanting (dpt). Second clusters plants were selected and divided into two group of early-symptomatic and late-symptomatic plants consisted of 12 plants, respectively for polymerase chain reaction (PCR) based begomovirus diagnosis and yield survey. Typical begomovirus symptom started to be observed at 30 dpt in small number of plants (3%) and reach the highest rate (100%) at 105 dpt. The difference productivity of early-symptomatic plants was 0,26 tons ha−1 higher than late-symptomatic plants. Begomovirus species which prevalently infect the plants both early and late symptomatic plants was pepper yellow leaf curl Indonesia virus (PepYLCIV).

A recombinant DNA‐satellite associated with Pepper yellow leaf curl Indonesia virus in highland area

Yellow curl disease caused by begomovirus is a major threat for horticulture in Indonesia. Control mea‐ sures for the disease face several constraints, one of which is the association between begomovirus and DNA satellites which can affect the severity of symptoms. In this study, we detected the presence of a DNA satellite associated with begomovirus in a highland area. The sample was obtained from Ketep, Magelang, located approximately 1400 meters above sea level. Begomovirus was detected using primers PAL1V1978/PAR1C715 that resulted in an amplicon of ap‐ proximately 1600bp. The presence of this satellite was detected using primers CLB36F/CLB37R, resulting in full‐length satellite genome of approximately 1300bp. Sequence analysis showed the sample was infected by Pepper yellow leaf curl Indonesia virus (PepYLCIV) and a non‐coding satellite which resembled some characteristics of common betasatellites with imperfect putative ORF βC1. SimPlot analysis revealed the recombination event between betasatellites and DNA‐B of PepYLCIV. The satellite found in this study is thought to be the result of recombination due to multiple infections in plants.

A recessive gene pepy-1 encoding Pelota confers resistance to begomovirus isolates of PepYLCIV and PepYLCAV in Capsicum annuum.

A begomovirus resistance gene pepy-1, which encodes the messenger RNA surveillance factor Pelota, was identified in pepper (C. annuum) through map-based cloning and functional characterization. Pepper yellow leaf curl disease caused by begomoviruses seriously affects pepper (Capsicum spp.) production in a number of regions around the world. Ty genes of tomato, which confer resistance to the tomato yellow leaf curl virus, are the only begomovirus resistance genes cloned to date. In this study, we focused on the identification of begomovirus resistance genes in Capsicum annuum. BaPep-5 was identified as a novel source of resistance against pepper yellow leaf curl Indonesia virus (PepYLCIV) and pepper yellow leaf curl Aceh virus (PepYLCAV). A single recessive locus, which we named as pepper yellow leaf curl disease virus resistance 1 (pepy-1), responsible for PepYLCAV resistance in BaPep-5 was identified on chromosome 5 in an F2 population derived from a cross between BaPep-5 and the begomovirus susceptible accession BaPep-4. In the target region spanning 34kb, a single candidate gene, the messenger RNA surveillance factor Pelota, was identified. Whole-genome resequencing of BaPep-4 and BaPep-5 and comparison of their genomic DNA sequences revealed a single nucleotide polymorphism (A to G) located at the splice site of the 9th intron of CaPelota in BaPep-5, which caused the insertion of the 9th intron into the transcript, resulting in the addition of 28 amino acids to CaPelota protein without causing a frameshift. Virus-induced gene silencing of CaPelota in the begomovirus susceptible pepper No.218 resulted in the gain of resistance against PepYLCIV, a phenotype consistent with BaPep-5. The DNA marker developed in this study will greatly facilitate marker-assisted breeding of begomovirus resistance in peppers.

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 IDENTIFICATION OF Pepper yellow leaf curl Indonesia virus ON CHILI PEPPER IN NUSA PENIDA ISLAND

Molecular identification of Pepper yellow leaf curl Indonesia virus on chili pepper in Nusa Penida Island. Pepper yellow leaf curl Indonesia virus (PYLCV) has been reported as caused yellow leaf curl disease in Bali Island since early 2012. Dominant symptoms of PYLCV infection in chili pepper were yellowing, leaf curl, yellow mosaic, and mottle. Bemisia tabaci, has been known to vector on the case yellow leaf curl disease. Observations on the Nusa Penida Island in 2020 showed symptoms such as yellow leaf curl disease, however, identification of PYLCV in Nusa Penida Island has not been studied. Molecular identification was conducted using polymerase chain reaction and sequence analysis. Data collected in this study was disease symptoms and disease incidence. The results showed that dominant disease symptoms caused by virus from Nusa Penida were yellow mosaic, yellowing, and mottle. Universal DNA fragments of 912 bp were successfully amplified from 50 leaf samples using Begomovirus degenerate primers SPG 1 (5’-CCCCKGTGCGWRAATCCAT-3’) and SPG 2 (5’ATCCVAA YWTYCAGGGAGCT-3’). Sequence analysis showed that the isolate from Nusa Penida was a Pepper yellow leaf curl Indonesia virus with a 98–100% homology with several reference isolates.

Ty-2 and Ty-3a Conferred Resistance are Insufficient Against Tomato Yellow Leaf Curl Kanchanaburi Virus from Southeast Asia in Single or Mixed Infections of Tomato.

Tomato yellow leaf curl virus (TYLCV), a monopartite begomovirus that originated in the eastern Mediterranean, has spread worldwide, becoming a serious threat to tomato (Solanum lycopersicum L.) production. Southeast Asia is considered one of the hotspots for begomovirus diversity, and a wide variety of local begomovirus species distinct from TYLCV have been identified. In this study, the protection effect of introgressions of single TYLCV Ty resistance genes, Ty-2 and Ty-3a, in tomato was examined against inoculations of the bipartite begomoviruses Tomato yellow leaf curl Kanchanaburi virus (TYLCKaV) and Pepper yellow leaf curl Indonesia virus (PepYLCIV) isolated from Indonesia. Our findings suggest that Ty-2 in the heterozygous state was found to be ineffective against PepYLCIV and TYLCKaV, whereas Ty-3a in the heterozygous state was effective against PepYLCIV and partially effective against TYLCKaV. Quantification of viral DNAs showed correlation between symptom expression and viral DNA accumulation. Moreover, mixed infections of TYLCKaV and PepYLCIV caused notably severe symptoms in tomato plants harboring Ty-3a. In cases of mixed infection, quantifying viral DNAs showed a relatively high accumulation of PepYLCIV, indicating that Ty-3a loses its effectiveness against PepYLCIV when TYLCKaV is also present. This study demonstrates the lack of effectiveness of Ty resistance genes against single and mixed infections of distinct local begomoviruses from Southeast Asia.

Effects of Mulch Type, Plant Cultivar, and Insecticide Use on Sweet Potato Whitefly Population in Chili Pepper.

One of the most devastating pests of chili pepper is the sweet potato whitefly (SPW), Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). It sucks plant sap, emits honeydew on which sooty mold fungi grow, and transmits the pepper yellow leaf curl Indonesia virus (PepYLCIV), the most damaging viral disease of chili in Indonesia. Farmers rely mainly on insecticide to control the insect with two to three sprays in a week. To reduce the insecticide use, an integrated approach needs to be developed. Therefore, the current study evaluated the effectiveness of the integration of reflective mulch, host plant resistance, and insecticide use for managing the sweet potato whitefly on the chili pepper. In 2018, a complete randomized block design was used in three separate trials to assess the effects of mulch, cultivar, or insecticide application frequency on the numbers of whitefly eggs, nymphs, and adults. In 2019, a split-split plot design was used to evaluate the effects of the integration of mulch, cultivar, and insecticide application frequency on the numbers of whitefly eggs, nymphs, and adults. The results showed that the reflective silver mulch had significantly lower numbers of whitefly eggs, nymphs, and adults, in comparison to the rice straw mulch and bare ground treatments. Chili plants cv. Bara was more resistant than Bhaskara against B. tabaci in the field; however, in the no-choice trial, no significant difference was detected between both cultivars. Insecticide applications twice per week and once per week were equally effective in controlling the whitefly on the susceptible cultivar (Bhaskara). Overall, the integration of reflective mulch, resistant cultivar, and insecticide application every two weeks effectively suppressed B. tabaci populations on the chili pepper. This approach could substantially reduce the number of insecticide applications from twice per week (commonly practiced by chili farmers in the area) to one application only in two weeks.

Validating Plant Genes Involved in Pepper Yellow Leaf Curl Indonesia Virus Infection Using VIGS in Model Plant Nicotiana benthamiana

&lt;p&gt;Pepper yellow leaf curl disease caused by Pepper yellow leaf curl Indonesia virus (PepYLCIV) has become a challenge to chili pepper cultivation. Development of resistant variety by utilizing recessive resistance gene is expected to control the disease in the field. This study aimed to validate three plant genes, namely deltaCOP, hsc70, and BAM1, in PepYLCIV infection by applying Virus-induced Gene Silencing (VIGS) in a model plant, wild type Nicotiana benthamiana. PepYLCIV and construct of Tobacco rattle virus (TRV) which induced silencing of each gene were co-inoculated into N. benthamiana plants through agroinfiltration. Gene expression and the relative amount of viral DNA were determined by quantitative reverse transcription PCR (qRT-PCR) and quantitative PCR (qPCR), respectively, at 15 days post inoculation. The results showed a decreased level of deltaCOP, hsc70, and BAM1 expressions to 66.4%, 53.0%, and 47.0%, respectively, compared to that in the control (100%). Silencing of the three genes decreased the accumulation of PepYLCIV to 0.1%, 18.4%, and 63.0%, respectively, compared to that in the control. deltaCOP and hsc70 genes were indicated to be involved in the viral infection and could be good candidate genes for obtaining chili pepper varieties resistant to PepYLCIV. This result affirmed that the reverse genetics technique could be an alternative approach for identifying plant genes involved in viral infection, including PepYLCIV. The use of an infectious clone in this study allows the virus inoculations could be carried out without rearing and maintaining its natural vector, hence reduces the risk of virus transmission to healthy plants.&lt;/p&gt;

Complete Genome Sequence of a Pepper Yellow Leaf Curl Indonesia Virus Isolated from Tomato in Bali, Indonesia.

We report a complete genome sequence of a pepper yellow leaf curl Indonesia virus (PepYLCIV) isolated in Bali, Indonesia. This virus shares around 90% identity with other PepYLCIV DNA-As and 86% identity with DNA-Bs, suggesting that it is a novel isolate of PepYLCIV.

The threat of seed-transmissible pepper yellow leaf curl Indonesia virus in chili pepper

Recently, chili pepper (Capsicum annuum) plants in Indonesia have been devastated by a notorious bipartite begomovirus infection named Pepper yellow leaf curl Indonesia virus (PepYLCIV), which causes a distinct decrease in chili pepper production. Pepper yellow diseases have been known since early 2000; however, the spread of this virus thus far is distressing. These diseases can reduce chili yields by 20–100% in Indonesia. As previously known, begomovirus can be transmitted through whitefly to several host plants from the families Solanaceae, Compositae, and Leguminosae. In the field, a single plant was observed with severe symptoms of pepper yellow leaf curl disease, while other plants in the same field were asymptomatic and healthy. The observation leads to the possibility that the virus can be transmitted from previously infected chili pepper plants through seeds, as begomovirus transmission through seeds has been reported before. This study was conducted using seeds from chili peppers infected with viruses from different places in Indonesia. Whole seeds, embryos, and seedlings from PepYLCIV infected seeds were investigated in this study by performing viral genome DNA extraction, uracil DNA glycosylase-PCR, and sequencing analysis. Results revealed that both DNA-A and DNA-B of PepYLCIV in seeds and embryos of infected chili pepper plants were detected. The results also showed that 25–67% of PepYLCIV DNA-A and 50–100% of DNA-B were detected from seedlings grown from infected chili pepper seed collected from different location, thus confirming PepYLCIV as a seed-transmissible virus in chili pepper plants.