Yellow Leaf Curl Disease Research Articles

Implementasi Artificial Neural Network (ANN) Backpropagation Untuk Klasifikasi Jenis Penyakit Pada Daun Tanaman Tomat

Tomato is a horticultural plant that can be easily found in Indonesia. Tomatoes are popular for public consumption because their nutritional values have excellent content for health, besides tomatoes are widely cultivated because the price is quite stable. However, there are obstacles in tomato plants cultivation for farmers because tomatoes are vulnerability to diseases, so that farmers have difficulty distinguishing types of diseases that look similar. Therefore, this research was conducted to help farmers in identifying various diseases in tomato leaves. This research uses Artificial Neural Network (ANN) method with backpropagation algorithm to classify the types of diseases in tomato leaves. The data used for testing were 50 image data of bacterial spot disease, 50 image data of yellow leaf curl disease, and 50 image data of healthy leaves. Tomato leaves types of diseases classification with the best result that utilized backpropagation with Cross-validation 4 folds by following the rules with batch size of 100, hidden layers defined as , the learning rate for weight updates is 0.3, with validation threshold is used to terminate validation testing is 20, and 500 as the number of epoch to train through, have been resulted in an accuracy of 78% which required time 319.77 seconds to process data. Which was then assisted by Confusion Matrix as a tool to measure the performance of the classification results that have been carried out and precision results of 0.78 so as to obtain 117 data of true positive.
 Keywords: Tomato, Leaf imagery classification, Artificial Neural Network (ANN), Backpropagation.

Effect of tomato yellow leaf curl disease on yield, height and chlorophyll of open field grown tomato genotypes in Oman

Effect of tomato yellow leaf curl disease on yield, height and chlorophyll of open field grown tomato genotypes in Oman

Fungal F8-Culture Filtrate Induces Tomato Resistance against Tomato Yellow Leaf Curl Thailand Virus

Tomato (Solanum lycopersicum) is an important economic crop worldwide. However, tomato production is jeopardized by the devastating tomato yellow leaf curl disease caused by whitefly-transmitted begomoviruses (WTBs). In this study, we evaluated the efficacy of our previously developed plant antiviral immunity inducer, fungal F8-culture filtrate, on tomato to combat tomato yellow leaf curl Thailand virus (TYLCTHV), the predominant WTB in Taiwan. Our results indicated that F8-culture filtrate treatment induced strong resistance, did not reduce the growth of tomato, and induced prominent resistance against TYLCTHV both in the greenhouse and in the field. Among TYLCTHV-inoculated Yu-Nu tomato grown in the greenhouse, a greater percentage of plants treated with F8-culture filtrate (43–100%) were healthy-looking compared to the H2O control (0–14%). We found that TYLCTHV cannot move systemically only on the F8-culture filtrate pretreated healthy-looking plants. Tracking the expression of phytohormone-mediated immune maker genes revealed that F8-culture filtrate mainly induced salicylic acid-mediated plant immunity. Furthermore, callose depositions and the expression of the pathogen-induced callose synthase gene, POWDERY MILDEW RESISTANT 4 were only strongly induced by TYLCTHV on tomato pretreated with F8-culture filtrate. This study provides an effective way to induce tomato resistance against TYLCTHV.

No Evidence for Seed Transmission of Tomato Yellow Leaf Curl Sardinia Virus in Tomato

Seed transmission is an important factor in the epidemiology of plant pathogens. Geminiviruses are serious pests spread in tropical and subtropical regions. They are transmitted by hemipteran insects, but a few cases of transmission through seeds were recently reported. Here, we investigated the tomato seed transmissibility of the begomovirus tomato yellow leaf curl Sardinia virus (TYLCSV), one of the agents inducing the tomato yellow leaf curl disease, heavily affecting tomato crops in the Mediterranean area. None of the 180 seedlings originating from TYLCSV-infected plants showed any phenotypic alteration typical of virus infection. Moreover, whole viral genomic molecules could not be detected in their cotyledons and true leaves, neither by membrane hybridization nor by rolling-circle amplification followed by PCR, indicating that TYLCSV is not a seed-transmissible pathogen for tomato. Examining the localization of TYLCSV DNA in progenitor plants, we detected the virus genome by PCR in all vegetative and reproductive tissues, but viral genomic and replicative forms were found only in leaves, flowers and fruit flesh, not in seeds and embryos. Closer investigations allowed us to discover for the first time that these embryos were superficially contaminated by TYLCSV DNA but whole genomic molecules were not detectable. Therefore, the inability of TYLCSV genomic molecules to colonize tomato embryos during infection justifies the lack of seed transmissibility observed in this host.

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.

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.

Transmission, characterization and occurrence of recombination in Indian strain of squash leaf curl China virus associated with yellow mosaic and leaf curl disease of Summer squash.

The online version contains supplementary material available at 10.1007/s13205-021-02821-9.

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%.

In silico: Coat Protein of PepYLCV-APWS

Pepper Yellow Leaf Curl Diseases [PepYLCD] one of the most damaging diseases in pepper and chili caused by a geminivirus. The coat protein of geminivirus plays an important role in encapsidation of the virus genome and also as a transmission mediator. This research aimed to predict the 3D structure and binding site of coat protein pepper leaf curl virus isolate Alahan Panjang, West Sumatera [PepYLCV-APWS]. The prediction was using swiss-model and chimera software for protein modeling. Furthermore, this study will be helpful to understand the similarity and the molecular-interaction to develop robust resistant strategies against geminiviruses in the nearby future.

The Global Dimension of Tomato Yellow Leaf Curl Disease: Current Status and Breeding Perspectives.

Tomato yellow leaf curl disease (TYLCD) caused by tomato yellow leaf curl virus (TYLCV) and a group of related begomoviruses is an important disease which in recent years has caused serious economic problems in tomato (Solanum lycopersicum) production worldwide. Spreading of the vectors, whiteflies of the Bemisia tabaci complex, has been responsible for many TYLCD outbreaks. In this review, we summarize the current knowledge of TYLCV and TYLV-like begomoviruses and the driving forces of the increasing global significance through rapid evolution of begomovirus variants, mixed infection in the field, association with betasatellites and host range expansion. Breeding for host plant resistance is considered as one of the most promising and sustainable methods in controlling TYLCD. Resistance to TYLCD was found in several wild relatives of tomato from which six TYLCV resistance genes (Ty-1 to Ty-6) have been identified. Currently, Ty-1 and Ty-3 are the primary resistance genes widely used in tomato breeding programs. Ty-2 is also exploited commercially either alone or in combination with other Ty-genes (i.e., Ty-1, Ty-3 or ty-5). Additionally, screening of a large collection of wild tomato species has resulted in the identification of novel TYLCD resistance sources. In this review, we focus on genetic resources used to date in breeding for TYLCVD resistance. For future breeding strategies, we discuss several leads in order to make full use of the naturally occurring and engineered resistance to mount a broad-spectrum and sustainable begomovirus resistance.

Vector Transmission of Tomato Yellow Leaf Curl Thailand Virus by the Whitefly Bemisia tabaci: Circulative or Propagative?

Simple SummaryTomato yellow leaf curl viruses cause disease epidemics in tomato crops in tropical and subtropical areas worldwide. The sweet potato whitefly, Bemisia tabaci, is a vector of this group of viruses. This research studied the transmission biology of tomato yellow leaf curl Thailand virus (TYLCTHV) by B. tabaci, including virus-infected tissues, virus translocation, virus replication, and transovarial transmission (i.e., transmission from mother to progeny via ovaries). We discovered that the virus first infects the alimentary gut, then the hemolymph, and finally the salivary glands of the whitefly. The virus did not replicate in the whitefly during infection. In addition, TYLCTHV was detected in only 10% of infected females’ first-generation progeny, but the progeny was unable to cause viral infection of tomato plants; therefore, there was no evidence of transovarial transmission. When combined with the current literature, our results suggest that B. tabaci transmits TYLCTHV in a persistent-circulative mode.Viruses that cause tomato yellow leaf curl disease are part of a group of viruses of the genus Begomovirus, family Geminiviridae. Tomato-infecting begomoviruses cause epidemics in tomato crops in tropical, subtropical, and Mediterranean climates, and they are exclusively transmitted by Bemisia tabaci in the field. The objective of the present study was to examine the transmission biology of the tomato yellow leaf curl Thailand virus (TYLCTHV) by B. tabaci, including virus-infected tissues, virus translocation, virus replication, and transovarial transmission. The results demonstrated that the virus translocates from the alimentary gut to the salivary glands via the hemolymph, without apparent replication when acquired by B. tabaci. Furthermore, the virus was detected in 10% of the first-generation progeny of viruliferous females, but the progeny was unable to cause the viral infection of host plants. There was no evidence of transovarial transmission of TYLCTHV in B. tabaci. When combined with the current literature, our results suggest that B. tabaci transmits TYLCTHV in a persistent-circulative mode. The present study enhances our understanding of virus–vector interaction and the transmission biology of TYLCTHV in B. tabaci.

CRISPR/Cas9-Mediated Generation of Pathogen-Resistant Tomato against Tomato Yellow Leaf Curl Virus and Powdery Mildew.

Tomato is one of the major vegetable crops consumed worldwide. Tomato yellow leaf curl virus (TYLCV) and fungal Oidium sp. are devastating pathogens causing yellow leaf curl disease and powdery mildew. Such viral and fungal pathogens reduce tomato crop yields and cause substantial economic losses every year. Several commercial tomato varieties include Ty-5 (SlPelo) and Mildew resistance locus o 1 (SlMlo1) locus that carries the susceptibility (S-gene) factors for TYLCV and powdery mildew, respectively. The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) is a valuable genome editing tool to develop disease-resistant crop varieties. In this regard, targeting susceptibility factors encoded by the host plant genome instead of the viral genome is a promising approach to achieve pathogen resistance without the need for stable inheritance of CRISPR components. In this study, the CRISPR/Cas9 system was employed to target the SlPelo and SlMlo1 for trait introgression in elite tomato cultivar BN-86 to confer host-mediated immunity against pathogens. SlPelo-knockout lines were successfully generated, carrying the biallelic indel mutations. The pathogen resistance assays in SlPelo mutant lines confirmed the suppressed accumulation of TYLCV and restricted the spread to non-inoculated plant parts. Generated knockout lines for the SlMlo1 showed complete resistance to powdery mildew fungus. Overall, our results demonstrate the efficiency of the CRISPR/Cas9 system to introduce targeted mutagenesis for the rapid development of pathogen-resistant varieties in tomato.

Comparative Efficacy of Silver Metallic Plastic Mulch, Botanicals and Insecticides in Controlling Tomato Yellow Leaf Curl Disease

Tomato Yellow Leaf Curl caused by Tomato Yellow Leaf Curl Virus (TYLCV) is one of the most important diseases of tomato causing heavy losses in yield and quality of fruits. Damage caused through phloem feeding and transmission of TYLCV by the insect vectors whitefly (Bemisiatabaci). In this study the competence of silver metallic plastic mulch, botanicals and insecticides were assessed to manage the Tomato Yellow Leaf Curl Virus (TYLCV) by controlling the insect vectors. In total 7 treatments including control were considered viz. T1=Imidacloprid, T2= ACmix, T3= Subicron, T4= Neemax, T5= Multineem, T6 = Silver metallic plastic mulch and T7= Control. All the treatments showed significant influence on different assayed parameters in the test crop tomato. The lowest disease incidence, disease severity and whitefly association was found in T6 treatment (silver metallic plastic mulch) that was 2.87%, 1.72% and 2.0% at 60 days after transplanting (DAT) respectively. While the highest disease incidence, disease severity and whitefly association were found in T7 treatment (control treatment) that was 14.71%, 46.22% and 18, respectively, at 60 DAT. From the relationship study between disease incidence and disease severity with whitefly association, it was revealed that disease incidence and severity of TYLCV was increased with increasing of whitefly population and vice-versa. Among the treatments, growth parameters, yield and yield attributers were also found better in T6treatment (silver metallic plastic mulch). Silver metallic plastic mulch is the best option to manage the TYLCV by controlling the insect vectors, whitefly instead of insecticides.
 SAARC J. Agri., 18(2): 77-86 (2020)

BEGOMOVIRUSES AND BETASATELLITES ASSOCIATED WITH CLCuD

Begomoviruses are one of the major types of plant viruses. They are transmitted by whitefly and cause many diseases. The CLCuD is the most damaging disease of cotton. It is the vector of begomoviruses, namely as monpartite or bipartite begomoviruses. Bipartite begomoviruses are consisted of A and B DNA molecuales. Monopatite consist of single genome. It is mainly linked with alphasatellites and betasatellites. Alphasatellites can replicate by using replication protein and not called as true satellites. Betasatellites are called as true satellites as they are linked with alphasatellites. Mainly cause tomato yellow leaf curl disease. Begomoviruses are different from other plant viruses as the basis of RNA genomes. DNA beta satellite is involves in suppressing the expressions of genes in plants. It has a major role in preventing RNA silencing by encoding proteins that binds with DNA and target the nucleus of cell. Affected plants show various symptoms such as leaf curling, enations etc. that cause loss in cotton field by preventing the growth. With the help of PCR, 1.4 kb fragments of DNA have been amplified from DNA template. For cloning the whole begomoviruses genome, a simple method of cloning has been widely used. Cloning is usually done by using the bacteriophage DNA polymerase. The betasatellites have shown association with CLCuD.

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>

Pyramiding Ty-1/Ty-3, Ty-2, ty-5 and ty-6 genes into tomato hybrid to develop resistance against tomato leaf curl viruses and recurrent parent genome recovery by ddRAD sequencing method

Tomato leaf curl virus (ToLCV) is a begomovirus transmitted by whitefly (Bemisia tabaci) and causes Tomato (yellow) leaf curl disease (TYLCD/ToLCD) in many parts of India and rest of the world resulting in huge economic losses. Many Ty genes identified either from wild and/or cultivated tomato, which confers various levels of resistance to ToLCV. The current study aimed at stacking four important resistant genes (Ty-1/Ty-3, Ty-2, ty-5, and ty-6) in parental lines of a commercial tomato hybrid JKTH811 with the aid of the marker-assisted backcross breeding program. As a donor source, two pre-breeding lines, CLN3125K (Ty-1/Ty-3 and Ty-2) and FLA456 (ty-5 and ty-6) was used. Crossed population screened by using tightly linked Ty genes specific markers for foreground selection and attempted the fastest recovery of recurrent parental genome through NGS based ddRAD sequencing approach. Ty genes introgressed parental lines as well as the resulting F1 hybrids were tested for their bio-efficacy against ToLCNDV (New Delhi var.) under greenhouse and field conditions. Disease severity of Ty genes pyramided female lines and F1 hybrids were found as significantly lower when compared to original parental lines and hybrid. This report demonstrates the efficiency of Ty genes pyramiding from different donors in a hybrid against ToLCV and recovery of the recurrent genome using the ddRAD-seq platform in the minimum generations possible.

Laboratory and UAV-Based Identification and Classification of Tomato Yellow Leaf Curl, Bacterial Spot, and Target Spot Diseases in Tomato Utilizing Hyperspectral Imaging and Machine Learning

Tomato crops are susceptible to multiple diseases, several of which may be present during the same season. Therefore, rapid disease identification could enhance crop management consequently increasing the yield. In this study, nondestructive methods were developed to detect diseases that affect tomato crops, such as bacterial spot (BS), target spot (TS), and tomato yellow leaf curl (TYLC) for two varieties of tomato (susceptible and tolerant to TYLC only) by using hyperspectral sensing in two conditions: a) laboratory (benchtop scanning), and b) in field using an unmanned aerial vehicle (UAV-based). The stepwise discriminant analysis (STDA) and the radial basis function were applied to classify the infected plants and distinguish them from noninfected or healthy (H) plants. Multiple vegetation indices (VIs) and the M statistic method were utilized to distinguish and classify the diseased plants. In general, the classification results between healthy and diseased plants were highly accurate for all diseases; for instance, when comparing H vs. BS, TS, and TYLC in the asymptomatic stage and laboratory conditions, the classification rates were 94%, 95%, and 100%, respectively. Similarly, in the symptomatic stage, the classification rates between healthy and infected plants were 98% for BS, and 99–100% for TS and TYLC diseases. The classification results in the field conditions also showed high values of 98%, 96%, and 100%, for BS, TS, and TYLC, respectively. The VIs that could best identify these diseases were the renormalized difference vegetation index (RDVI), and the modified triangular vegetation index 1 (MTVI 1) in both laboratory and field. The results were promising and suggest the possibility to identify these diseases using remote sensing.

Potency of Yeasts to Promote Induced Resistance on Chili Plant (Capsicum annuum L.) against Yellow Leaf Curl Disease

Yellow leaf curl is a major disease on chili plants. The use of antagonistic yeasts as the control agents is a good alternative in an environmentally friendly control method. This study was objected to evaluate the potencies of Rhodotorula minuta and Candida tropicalis to promote induced resistance on chili plants against yellow leaf curl disease. The experiment was arranged in the randomized complete block design with 9 treatments and 3 replications. The treatments were the application of the yeasts at three different times of virus inoculation, as follows: A. R. minuta, virus inoculation at 3 days after transplanting (dat), B. R. minuta, virus inoculation at 7 dat, C. R. minuta, virus inoculation at 10 dat, D. C. tropicalis, virus inoculation at 3 dat, E. C. tropicalis, virus inoculation at 7 dat, F. C. tropicalis, virus inoculation at 10 dat, G. control, virus inoculation at 3 dat, H. control, virus inoculation at 7 dat, and I. control, virus inoculation at 10 dat. No treatment was applied to the control. The yeasts were applied by soaking the chili seeds, and pouring the suspension into the growth media at transplanting. The variables observed were incubation period, disease severity, and disease incidence. Peroxidase activity, phenylalanine ammonia lyase activity, and salicylic acid accumulation were also analyzed. The results showed that the application of R. minuta or C. tropicalis was able to extend the disease incubation period, but did not reduce the yellow leaf curl disease incidence and severity. The treatment of R. minuta, virus inoculation at 7 dat, increased the peroxidase activity from 2590.80 units to 6870.93 units (0.5 minute) and from 577.367 units to 1131.300 units (2.5 minutes), PAL activity from 16.059 to 17.911 A290/mg, and accumulation of salicylic acid from 2.785 to 6.263 ppm. Application of C. tropicalis, virus inoculation at 7 dat, increased the peroxidase activity from 2590.80 units to 6033.067 units (0.5 minute) and from 577.367 units to 950.967 units (2.5 minutes), and accumulation of salicylic acid from 2.785 to 6.982 ppm.

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

<p>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.</p>

Association of a begomovirus-satellite complex with yellow vein and leaf curl disease of hollyhock (Alcea rosea) in India.

Geminiviruses cause considerable yield loss in several crop plants worldwide. In 2016, several hollyhock plants displaying yellow mosaic and leaf curling symptoms were noticed in a nursery of Jawaharlal Nehru University, New Delhi, India. Analysis of the collected samples indicated an association of monopartite and bipartite begomoviruses with satellites. Three begomoviruses (including a member of a new begomovirus species), two alphasatellites, and a betasatellite were isolated from yellow-mosaic-disease-affected plants. Similarly, a begomovirus, two alphasatellites, and a betasatellite were found to be associated with leaf curl disease of hollyhock. These begomoviruses and satellites were found to be recombinants. By harboring diverse begomoviruses and satellite DNAs, hollyhock may serve as a potential source of virus inoculum.