Chilli Leaf Curl Virus Research Articles

Screening of chilli varieties for resistance to chilli leaf curl virus and chilli leaf curl Sri Lanka virus by agroinoculation

Screening of chilli varieties for resistance to chilli leaf curl virus and chilli leaf curl Sri Lanka virus by agroinoculation

Evaluation of F2 Segregating Population of Chilli (Capsicum annuum L.) for Yield and Leaf Curl Virus Resistance

Chilli (Capsicum annuum L.) is an important vegetable crop, cultivated worldwide for its fruits which are valued for pungency, flavor, and nutritional benefits. However, chilli production is significantly restricted by various biotic stresses, especially the Chilli leaf curl virus (CLCV). The present study was conducted at the Department of Vegetable Science, College of Agriculture, Vellayani, Kerala Agricultural University during 2020-2021 to evaluate the F2 segregating population of chilli crosses viz., CHIVAR-6 x Sel-4 and CHIVAR-10 x Sel-3 for yield and leaf curl virus resistance. Evaluation of vegetative and yield related traits was conducted on these populations under the field conditions. Significant variability was observed for various traits such as plant height, fruits per plant, fruit length, yield per plant and resistance to leaf curl virus. The scoring for chilli leaf curl virus was done and based on the scoring the segregants were categorized into highly resistant, resistant, moderately resistant, moderately susceptible, susceptible and highly susceptible. Among the F2 population of the first cross, fruits per plant, plant height, fruit weight and fruit girth showed high and positive correlation with yield per plant. The segregants of the second cross recorded significant positive correlation for fruits per plant, plant height and fruit length with yield. The results of the study provide valuable insights into breeding for both high yield and leaf curl virus resistance, crucial for enhancing chilli production under the challenging situations.

Molecular characterization of Begomovirus and Beta satellite virus associated with leaf curl disease of Chilli (Capsicum annum L.) in southern parts of Tamil Nadu

Chilli is one of the widely cultivated commercial vegetable crops in India. Chilli leaf curl is the most devasting disease and causes a yield loss of 100 per cent in Chilli. Fourteen begomovirus species cause chilli leaf curl disease (ChiLCD). An extensive survey was carried out in 2023 to determine the prevalence of the leaf curl disease of Chilli caused by begomovirus in major chilli-growing areas of the Southern Districts of Tamil Nadu. During the survey, 21 isolates of begomovirus infecting Chilli were collected. Among the 21 isolates, the isolate collected from Kalakudi village (BV-KI) exhibited severe symptoms.DNA extracted from 21 isolates of begomovirus were subjected to PCR by using Rojas universal primers, Chilli leaf curl virus (ChiLCV) Coat protein primers and beta satellite virus primers and obtained 1380 bp, 1100 bp and 1400 bp amplicons of top and coat protein region of DNA-A of begomovirus, Chilli leaf curl virus coat protein region and beta satellite virus associated with ChiLCV respectively. The 1380 bp, 1100 bp and 1400 bp amplicons obtained from the BV-KI isolate were sequenced and submitted to the NCBI. The sequences were blast analyzed, and it showed that the nucleotide sequence of the top and coat protein region of DNA-A of begomovirus and CP gene of ChiLCV BV-KI isolate was found to have 90.61 and 99.78% similarity with Bhavanisagar (NC 055130.1) isolate respectively. The nucleotide sequence of the beta satellite virus of BV-KI isolate was found to have 99.93% similarity with the Chilli leaf curl beta satellite virus Meerut (MH355642.1) isolate.

In-silico prediction of domain involved in chilli protein interaction with chilli leaf curl virus and associated betasatellite encoded protein

The begomovirus-caused chilli leaf curl disease (ChiLCD) is a significant hindrance to the production of chilies (Capsicum annuum) in many chilli-growing regions worldwide. Begomoviruses are involved in protein interactions with plants to disrupt their host’s defence mechanisms. Our earlier research demonstrated that the betasatellite monopartite association on chilli plants increases the activity of the AV2 gene. Here, we predict the interacting regions among chilli-begomovirus proteins. In this study, we used seven begomoviral proteins encoded by the chilli leaf curl virus (ChiLCV Acc. No. MZ540908) and chilli leaf curl betasatellite (ChLCuB Acc. No. MZ540909) that interacted with the host proteins adenylate kinase (ADK), glycoxalases (GLO1), suppressor of gene silencing 3 (SGS3), and S-phase kinase-associated protein 1 (SKP1). We applied a range of computational approaches, including physiochemical analysis, homology modeling, domain prediction, binding site, and interface prediction. Several in silico interaction prediction approaches based on sequence and structure indicated a significant potential binding with the host proteins GLO1 and ADK. Our findings showed that the interactions between ChiLCV-A and ChCLuB are mediated by the ADK and GLO1 domains encoded by C. annuum. Similarly, in HADDOCK the AC1 and AV1 complexes with GLO1 and ADK had the lowest binding energies, respectively. The optimum and lowest binding energies for the βC1 interaction were found in the PyRx tool. We also predicted and validated the deletion and substitution sites within ADK and GLO1 proteins. This is the first systematic investigation of the interactions between the ADK, GLO1, SGS3, and SKP1 chilli proteins and ChiLCV-A and ChCLuB-encoded proteins. The findings of the present study will assist researchers in comprehending the role of viral proteins in chilli leaf curl disease.

Evaluation of Hybrids and Parents of Chilli (Capsicum annuum L.) for Yield and Resistance to Chilli Leaf Curl Virus

Evaluation of Hybrids and Parents of Chilli (Capsicum annuum L.) for Yield and Resistance to Chilli Leaf Curl Virus

Exploring Host Resistance against Chilli Leaf Curl Disease in a Tolerant Chilli Genotype.

In tropical countries, combating leaf curl disease in hot peppers has become important in improvement programs. Leaf curl disease is caused by whitefly (Bemisia tabaci) transmitted begomoviruses, which mainly include chilli leaf curl virus (ChiLCV). However, multiple begomoviruses have also been found to be associated with this disease. The Capsicum annuum line, DLS-Sel-10, was found to be a tolerant source against this disease during field screening. In this study, we characterized the resistance of DLS-sel-10 against chilli leaf curl virus (ChiLCV) in comparison to the susceptible cultivar Phule Mukta (PM), focusing on the level, stage, and nature of resistance. Comprehensive investigations involved screening of DLS-Sel-10 against the whitefly vector ChiLCV. The putative tolerant line displayed reduced virus infection at the seedling stage, with increasing resistance during vegetative, flowering, and fruiting stages. Both DLS-Sel-10 and PM could be infected with ChiLCV, although DLS-Sel-10 remained symptomless. Insect feeding assays revealed DLS-Sel-10 as a less preferred host for whiteflies compared to PM. In conclusion, DLS-Sel-10 demonstrated tolerance not only to ChiLCV but also served as an unfavorable host for the whitefly vector. The study highlighted an age-dependent increase in tolerance within DLS-Sel-10, showcasing its potential for effective leaf curl disease management in chilli.

Chilli Leaf Curl Disease: An Emerging Threat to Chilli Cultivation in Maharashtra, India

Chilli leaf curl disease (ChiLCD) locally known as ‘Churda Murda’ is a most destructive disease of chilli (Capsicum annuum) in India. The ChiLCD is caused by whitefly (Bemisia tabaci)-transmitted Begomovirus, belonging to the family Geminiviridae. A study was conducted to investigate the current status of ChiLCD in Maharashtra. Survey was carried out in chilli growing districts of Maharashtra to study the disease incidence (DI) and percent diseases index (PDI) of ChiLCD. Artificial Intelligence (AI)-based application (App) ‘Plantix–your crop doctor’ was used to assess the diagnosis of ChiLCD. During the survey different symptoms of ChiLCD, leaf curling, leaf yellowing, crinkling, puckering, vein banding and stunting were observed in diseased chilli plants. In this study, ‘Plantix–your crop doctor’ App accurately diagnosed the ChiLCD and its pathogen Chilli leaf curl virus (ChiLCV). High ChiLCD incidence of 85-100% with PDI of 53.8-62.7% was observed at Kemwadi village in Osmanabad district and 80-90% with PDI of 42.3-45.7% at Ranmasle village in Solapur district of Maharashtra. The high incidence of ChiLCD in Maharashtra has been taken into consideration and this can be correlated with various factors such as weather conditions, insecticide resistance in whitefly populations, and the appearance of virulent strains of ChiLCV. Early detection of ChiLCV using the AI-based ‘Plantix–your crop doctor’ App and effective management of insect vector whitefly could prevent ChiLCV spread and minimize the crop yield losses.

Breeding chili pepper for simultaneous improvement in leaf curl virus and anthracnose disease tolerance and commercially important traits

ABSTRACT In a large portion of the tropics, there is a demand for the development of hybrid chilies (Capsicum annuum L.) with high pungency, antioxidant vitamins, and tolerance to chili leaf curl virus, and anthracnose. Six genetically diverse parents were crossed in half-diallel fashion to develop 15 F1 hybrids to assess the level of heterosis, combining ability and gene action for 17 quantitative traits. The inheritance of most traits was apparently controlled by non-additive gene action. “Bidhan Chili 4” recorded the maximum, significant, GCA effects in a desired direction for PDIs of leaf curl virus and anthracnose along with commercially important traits. The maximum extent of heterobeltiosis was for oleoresin content followed by ascorbic acid and capsaicin contents, PDIs of chili leaf curl virus and anthracnose, and fruit yield per plant. The hybrids “Bidhan Chili 4 × Chili 38-Ragi” and “Pant C 1 × Bidhan Chili 4” could be isolated on the basis of their average performance, heterosis manifested in them, and SCA effects. Such hybrids could make a difference by meeting the horticultural requirements, high yield, disease tolerance and pungency, of commercial chili growing zones in the tropics. Hybrid vigor is available for commercial production of chili hybrids. A different approach from hybrid vigor is to isolate pure lines from segregating generations of potential heterotic F1s to increase fruit yield, quality attributes, and resistance to the chili leaf curl virus and anthracnose disease.

Biochemical changes in chilli (Capsicum annuum L.) leaves infected with chilli leaf curl virus (CLCV)

Biochemical changes in chilli (Capsicum annuum L.) leaves infected with chilli leaf curl virus (CLCV)

Phenotyping of wild species and development of interspecific hybrids for resistance against Chilli leaf curl virus disease in chilli

Phenotyping of wild species and development of interspecific hybrids for resistance against <i>Chilli leaf curl virus</i> disease in chilli

Current status, breeding strategies and future prospects for managing chilli leaf curl virus disease and associated begomoviruses in Chilli (Capsicum spp.).

Chilli leaf curl virus disease caused by begomoviruses, has emerged as a major threat to global chilli production, causing severe yield losses and economic harm. Begomoviruses are a highly successful and emerging group of plant viruses that are primarily transmitted by whiteflies belonging to the Bemisia tabaci complex. The most effective method for mitigating chilli leaf curl virus disease losses is breeding for host resistance to Begomovirus. This review highlights the current situation of chilli leaf curl virus disease and associated begomoviruses in chilli production, stressing the significant issues that breeders and growers confront. In addition, the various breeding methods used to generate begomovirus resistant chilli cultivars, and also the complicated connections between the host plant, vector and the virus are discussed. This review highlights the importance of resistance breeding, emphasising the importance of multidisciplinary approaches that combine the best of traditional breeding with cutting-edge genomic technologies. subsequently, the article highlights the challenges that must be overcome in order to effectively deploy begomovirus resistant chilli varieties across diverse agroecological zones and farming systems, as well as understanding the pathogen thus providing the opportunities for improving the sustainability and profitability of chilli production.

Infectivity analysis of chilli leaf curl Ahmedabad virus and its associated tomato leaf curl Bangladesh betasatellite complex in chili

Chilli leaf curl virus is responsible for inducing leaf curl disease in Chili (Capsicum annum L.), with whitefly (Bemisia tabaci) serving as the vector for transmission. Chili leaf samples with leaf curl symptoms were collected from Guntur, Andhra Pradesh, India. PCR-based detection screened for begomoviral infection and betasatellite in the collected samples. In this study, we have characterized tomato leaf curl Bangladesh betasatellite (ToLCBB) (OQ184745) using universal betasatellite primers. Partial dimer constructs were developed using the betasatellite and the DNA A genome of the chilli leaf curl Ahmedabad virus (ChiLCAV) (MW316419) in pCAMBIA 1302 vector. Both the constructs were mobilized separately into the Agrobacterium strain LBA4404, followed by agroinfiltration into healthy chili plants. Plants co-infiltrated with DNA A and betasatellite dimers exhibited symptoms after 21 days of infiltration, whereas plants infiltrated separately with the partial dimer constructs did not display any symptoms. Prominent symptoms include upward curling, thickening of stem ribs and stunted plant growth. Chili plants infiltrated with the infectious clones of ChiLCAV + ToLCBB and ChiLCAV alone showed positive amplification with ChiLCAV-specific and betasatellite primers. In contrast, plants infiltrated with ToLCBB partial dimer construct did not show any amplification with betasatellite primers. ChiLCAV DNA A titer accumulation was further quantified with qPCR and we observed that there is a significant increase (p < 0.0001) in the accumulation level with ChiLCAV + ToLCBB construct when compared to the ChiLCAV construct alone. Thus, this study highlights the pathogenesis of leaf curl disease in C. annuum caused by the begomovirus complex of ChiLCAV and its associated betasatellite ToLCBB.

Association of a novel begomovirus species with fenugreek yellow vein disease in India.

Fenugreek (Trigonella foenum-graecumL.) is an annual medicinal and spice crop belonging to the family Fabaceae. The occurrence of a yellow vein disease was recorded in fenugreek in Jodhpur (India) in 2022. The infection of begomoviruses in legume crops results in significant yield loss and major economic loss. The current study reports an association of a novel begomovirus species associated with yellow vein disease in Fenugreek. In symptomatic fenugreek plants, geminivirus-like particles were visible under a transmission electron microscope. Further, nucleotide sequence analysis of the rolling circle amplified product revealed 2743 nucleotide DNA-A genome with close relatedness to French bean leaf curl virus (88.21%) and Senna leaf curl virus (87.63%). It was proposed as a new begomovirus species, Fenugreek yellow vein Rajasthan virus. The genome organization suggested the presence of a typical nonanucleotide sequence along with 7 ORFs in DNA-A. A possible recombination event took place in the coat protein (V1) region with Pedilanthus leaf curl virus and Chilli leaf curl virus as major and minor parents. The recombinant virus poses possible threats to several other legume crops. To the best of our knowledge, this is the first report of the association of FeYVRaV with fenugreek yellow vein disease from northwestern India. In conclusion, the presence of a novel begomovirus species associated with yellow vein disease in fenugreek is alarming and needs further studies on its infectivity to prevent its spread to legume crops.

Geographical distribution of tomato-infecting begomoviruses in major cucurbits in India: a diagnostic analysis using begomovirus species specific PCR.

Cucurbits are an essential summer-season vegetable crops, but they are highly vulnerable from a range of abiotic and biotic factors. One of the significant biotic factors posing a growing menace to the production of major cucurbits in India is the emergence of tomato-infecting begomoviruses. In this study, we utilized PCR-based species-specific primers, developed earlier in our laboratory for the detection of begomoviruses infecting tomato and chilli plants, to identify begomoviruses in cucurbits across various regions of India. Leaf samples from major cucurbits were collected from different regions of Haryana, Delhi, Uttar Pradesh, Chhattisgarh, Maharashtra, Telangana and Karnataka, during the year 2020-2021. Total nucleic acid (TNA) was extracted from the samples and subjected to PCR using a generic primer specific to begomoviruses. The samples that exhibited positive amplification were further tested using six different species-specific primers targeting specific begomovirus species, namely Tomato leaf curl New Delhi virus (ToLCNDV), Tomato leaf curl Palampur virus (ToLCPalV), Tomato leaf curl Bangalore virus (ToLCBV), Tomato leaf curl Joydebpur virus (ToLCJoV), Tomato leaf curl Gujarat virus (ToLCGuV), and Chilli leaf curl virus (ChiLCV). The PCR analysis revealed that among the 551 plant samples tested, a total of 124 samples exhibited positive amplification using the universal begomovirus PCR. Specifically, 47 samples tested positive for ToLCNDV, 73 samples were positive for ToLCPalV and only one sample showed positive amplification for ChiLCV. However, none of the samples tested positive for ToLCJoV, ToLCGuV and ToLCBV. These findings from our study indicate the prevalence of ToLCNDV and ToLCPalV in major cucurbits across India. Furthermore, the study highlights the varied distribution of begomoviruses in major cucurbits between northern and southern regions of India.

Assessing the Resistance of Different Chili Genotypes to Chili Leaf Curl Virus (Chilcv) and Evaluating Insecticides for Controlling its Vector, Bemisia Tabaci

The production of chili in Pakistan is currently facing a significant threat from Chili leaf curl virus (ChiLCV). A study was conducted in the crop growing seasons 2019-2020 and 2020-2021 at Ayub Agriculture Research Institute Faisalabad to assess the susceptibility and resistance of nine chili genotypes to ChiLCV. Each genotype was replicated three times by using the Randomized Complete Block Design. Weekly documentation was carried out to record the incidence and severity of the disease. During the first and second crop growing seasons, it was observed that, Tarapuri (78%, 76.9%), CH 107 (67.8%, 63.7%), Talhari (65.7%, 56.8%), CH 109 (52.7%, 54.4%), CH 108 (50.8, 51.1), and GSL-111 (42.6%, 39.5%) genotypes showed susceptible response to ChiLCV. The two genotypes Hybrid-46 (17.7%, 18.5%) and Hot Queen (15.5%, 13.4%) exhibited a moderately resistant response and only one genotype CBS1292 (40.7%, 39.1%) showed a moderately susceptible response against ChiLCV. The results of the screening experiment indicated that a majority of chili varieties exhibit susceptibility to chili leaf curl disease and the most of the germplasm is deficient in terms of providing protection against the disease. In addition, another study was conducted to evaluate the effectiveness of five insecticides, namely Acephate 75 SP, Emamectin, Imidacloprid, Diafenthiuron, and a combination of these insecticides, in managing percent disease incidence, reducing whitefly population, and enhancing crop yield. Among the various insecticides evaluated, Diafenthiuron exhibited the highest efficacy in reducing disease incidence (7.70%, 6.66%), reducing white fly population (1.80, 1.56), and increasing the yield of green fruit (120.71, 132.52q/ha) followed by combination of all of these inecticides, Imidacloprid, Emamectin, and Acephate during both crop growing seasons. This approach has proved a high level of safety and ecological compatibility, and it appeared to be a practical disease management tool.

Assessment of Incidence of Chilli Leaf Curl Virus, Role of Environment and Disease Management

The present study “Assessment of incidence of chilli leaf curl virus, role of environment and its management” was carried out at Chilli LCV pone are of Bundelkhand region at Tikamagarh location of Madhya Pradesh. Among diseases affecting chilli crop, leaf curl virus is one of the major threat. In experiment, 10 chilli cultivars namely ZH-927, Gypsy, Pusa Jawala, Surya Pariksha, Surya-31, Meenam-(074), Mahy-Yasash, Disha, Pride and Arka Harita were screened under open field conditions for leaf curl virus. Six insecticides viz., Methyle dematon 25 EC @ 0.025%, Imidacloprid 17.8 SL @ 0.003%, Acetamaprid 20 SL @ 0.025%, Diamethoate 30 EC @ 0.5%, Thiamethoxam 70 WG@ 0.005% and Neem seed kernel extract @ 5% were tested against disease. In screening among all cultivers, ZH-927 was identified as resistant whereas Surya Pariksha, Disha and Arka Harita showed susceptible reaction. In case of management of leaf curl virus vector, Imidacloprid and Acetamaprid were found effective in inhibiting the leaf curl disease incidence followed by Thiomethoxam, NSKE, Methyl demeton and dimethoate. Temperature was found positive correlation with disease incidence. As the temperature increases, there is a corresponding increase in the incidence of the disease. Relative humidity and rainfall showed negative correlation with disease incidence as relative humidity and precipitation increased the disease incidence will decrease.

Simplified extraction protocol for plant tissues and reverse transcription RPA assay for quick and reliable diagnosis and its application in resistance screening of chilli veinal mottle virus

The widespread occurrence and predominant association of chilli veinal mottle virus (ChiVMV) with the valuable chilli landraces of North East Region (NER) of India and associated threat to chilli production necessitated the development of simplified and robust detection procedure. Present study reports a simplified reverse transcription-recombinase polymerase amplification (RT-RPA) method for detection of ChiVMV in crude leaf extract prepared through simplified extraction protocol using NaOH:EDTA (1:1) based tissue lysis, without the need of conventional RNA extraction and sample processing. Developed RT-RPA assay could be performed at an isothermal temperature (38 °C) in 30 min and exhibited no cross-reactivity with other prevalent chilli viruses (potato virus Y, cucumber mosaic virus, large cardamom chirke virus, capsicum chlorosis orthotospovirus, pepper mild mottle virus and chilli leaf curl virus), indicating high specificity. It could detect ChiVMV up to 10−9 dilution (100 ag/μl) of crude leaf extract, 10 ag/μl of RNA of ChiVMV infected leaf tissues and plasmid DNA containing viral gene insert, thus exhibiting sufficient sensitivity which is at par or better than the standard RT-PCR. Developed RT-RPA assay was employed to reveal the widespread occurrence of ChiVMV in NER India with 50.81% (1545 samples tested) of symptomatic and 7.85% (1593 samples tested) of asymptomatic samples tested positive. RT-RPA exhibited higher sensitivity in detection of ChiVMV infection in field samples as compared to the standard RT-PCR which gave false negative in 2.07% of symptomatic and 2.01% of asymptomatic samples. The developed assay was further applied in screening of 49 chilli germplasm for ChiVMV infection. The pooled results of field screening based on the disease score indicated that none of the chilli germplasm had immune or complete resistance, while 29 chilli germplasm (bird's eye chilli: C. frutescens; Morokatekpa: C. annuum, Leihao morok, Morok masingkha; Chingpimorok: Capsicum sp.) exhibited tolerant reaction with a disease score of 1.27–2.00. All the tested bird's eye chilli germplasm showed tolerance to the ChiVMV. The artificial screening to the severe isolate and qRT-PCR based viral titre determination confirmed the results of field screening wherein the germplasm RCMC6, RCMC7, RCMC17, RCMC27 and RCMC42 exhibited either asymptomatic or mild mosaic symptoms and decrease in viral titre at 20 DAI thus categorized as tolerant. The simplified RT-RPA assay developed and validated in the present study can be applied in routine detection of ChiVMV in field samples, disease-free seedling production and resistance screening under resource poor laboratory setup with limited technical expertise. Chilli germplasm with tolerance to ChiVMV identified in the present study can be used as donors in resistance breeding.

Diversity and phylogeography of begomoviruses and DNA satellites associated with the leaf curl and mosaic disease complex of eggplant

Eggplant is one of the important vegetable crops grown across the world, and its production is threatened by both biotic and abiotic stresses. Diseases caused by viruses are becoming major limiting factors for its successful cultivation. A survey for begomovirus-like symptoms in 72 eggplant fields located in six different Indian states revealed a prevalence of disease ranging from 5.2 to 40.2%, and the symptoms recorded were mosaic, mottling, petiole bending, yellowing, and upward curling, vein thickening, and enation of the leaves, and stunting of plants. The causal agent associated with these plants was transmitted from infected leaf samples to healthy eggplant seedlings via grafting and whiteflies (Bemisia tabaci). The presence of begomovirus was confirmed in 72 infected eggplant samples collected from the surveyed fields exhibiting leaf curl and mosaic disease by PCR using begomovirus specifc primers (DNA-A componet), which resulted in an expected amplicon of 1.2 kb. The partial genome sequence obtained from amplified 1.2 kb from all samples indicated that they are closely related begomovirus species, tomato leaf Karnataka virus (ToLCKV, two samples), tomato leaf curl Palampur virus (ToLCPalV, fifty eggplant samples), and chilli leaf curl virus (ChLCuV, twenty samples). Based on the partial genome sequence analysis, fourteen representative samples were selected for full viral genome amplification by the rolling circle DNA amplification (RCA) technique. Analyses of fourteen eggplant isolates genome sequences using the Sequence Demarcation Tool (SDT) indicated that one isolate had the maximum nucleotide (nt) identity with ToLCKV and eight isolates with ToLCPalV. Whereas, four isolates four isolates (BLC1-CH, BLC2-CH, BLC3-CH, BLC4-CH) are showing nucleotide identity of less than 91% with chilli infecting viruses begomoviruses with chilli infecting begomoviruses and as per the guidelines given by the ICTV study group for the classification of begomoviruses these isolates are considered as one novel begomovirus species, for which name, Eggplant leaf curl Chhattisgarh virus (EgLCuChV) is proposed. For DNA-B component, seven eggplant isolates had the highest nt identity with ToLCPalV infecting other crops. Further, DNA satellites sequence analysis indicated that four betasatellites identified shared maximum nucleotide identity with the tomato leaf curl betasatellite and five alphasatellites shared maximum nucleotide identity with the ageratum enation alphasatellite. Recombination and GC plot analyses indicated that the bulk of begomovirus genome and associated satellites presumably originated from of previously known mono and bipartite begomoviruses and DNA satellites. To the best of our knowledge, this is India's first report of ToLCKV and a noval virus, eggplant leaf curl Chhattisgarh virus associated with eggplant leaf curl disease.

Molecular Characterization of a Bipartite Begomovirus and an Alphasatellite Associated with Leaf Curl and Mosaic Disease of Bitter Gourd in Punjab

Bitter gourd (Momordica charantia) is an economically important vegetable and medicinal plant that gets infected by a number of viruses. A survey was conducted in and around Jalandhar region of Punjab, India to study viral symptoms in the bitter gourd fields. The plants showed reduced fruit size, upward leaf curling and mosaic symptoms, indicating begomovirus infection. DNA was isolated from the symptomatic leaves and tested for begomovirus infection using group-specific PCR primers. Amplified products were cloned into pMD20-T vector and sequenced. Based on the obtained sequence, new sets of primers were designed and used for amplification of complete DNA-A and DNA-B. Complete DNA-A and DNA-B were cloned in pMD20-T and sequenced. Sequence analysis of the present DNA-A and DNA-B showed their highest identity with Tomato leaf curl New Delhi virus (ToLCNDV). The associated Tomato leaf curl New Delhi alphasatellite was amplified using universal primers, cloned and sequenced. In phylogenetic analysis, the present DNA-A and DNA-B grouped with ToLCNDV isolates and other begomoviruses reported from bitter gourd. Phylogenetic analysis of the present alphasatellite showed its closet identity with Tomato leaf curl New Delhi alphasatellite. Recombination analysis of the DNA-A sequence showed that the present bitter gourd isolate might be a recombinant of Squash leaf curl China virus (SLCChV) as a major parent and Chilli leaf curl virus as a minor parent. Analysis of the DNA-B suggested it to be a recombinant of SLCChV as a major parent and Chyaote enation yellow mosaic virus as a minor parent. The present alphasatellite might be a recombinant of Tomato yellow spot alphasatellite as a major parent and Croton yellow mosaic alphasatellite as a minor parent. The percent identities of the nucleotide and amino acid sequences validate and support the results of the phylogenetic and recombination analyses.

Leaf Curl Epidemic Risk in Chilli as a Consequence of Vector Migration Rate and Contact Rate Dynamics: A Critical Guide to Management.

Chilli is an important commercial crop grown in tropical and subtropical climates. The whitefly-transmitted chilli leaf curl virus (ChiLCV) is a serious threat to chilli cultivation. Vector migration rate and host-vector contact rate, the major drivers involved in the epidemic process, have been pinpointed to link management. The complete interception of migrant vectors immediately after transplantation has been noted to increase the survival time (to remain infection free) of the plants (80%) and thereby delay the epidemic process. The survival time under interception (30 days) has been noted to be nine weeks (p < 0.05), as compared to five weeks, which received a shorter period of interception (14-21 days). Non-significant differences in hazard ratios between 21- and 30-day interceptions helped optimize the cover period to 26 days. Vector feeding rate, estimated as a component of contact rate, is noted to increase until the sixth week with host density and decline subsequently due to plant succulence factor. Correspondence between the peak time of virus transmission or inoculation rate (at 8 weeks) and contact rate (at 6 weeks) suggests that host succulence is of critical importance in host-vector interactions. Infection proportion estimates in inoculated plants at different leaf stages have supported the view that virus transmission potential with plant age decreases, presumably due to modification in contact rate. The hypothesis that migrant vectors and contact rate dynamics are the primary drivers of the epidemic has been proved and translated into rules to guide management strategies.