Papaya Ringspot Virus Research Articles

Integrated management of papaya pests in Veracruz: Papaya ringspot virus, papaya mealybug and mites

Integrated management of papaya pests in Veracruz: <i>Papaya ringspot virus</i>, papaya mealybug and mites

Breeding for resistance againstPapaya ringspot virus: history, present status and future prospects in India

Breeding for resistance against<i>Papaya ringspot virus</i>: history, present status and future prospects in India

Simultaneous detection of three common potyviruses infecting cucurbits by multiplex reverse transcription polymerase chain reaction assay

Watermelon mosaic virus (WMV), Zucchini yellow mosaic virus (ZYMV), and Papaya ring spot virus (PRSV-W) are the three most common potyviruses infecting cucurbits in the United States of America. In this study, a Multiplex reverse transcription polymerase chain reaction (RT-PCR) assay was developed for the simultaneous detection and differentiation of WMV, ZYMV, and PRSV-W. A mixture of specific primers set for each virus successfully amplified a distinct PCR product of 980 bp from the coat protein (CP) gene of WMV, 708 bp from the cylindrical inclusion (CI) gene of ZYMV and 496 bp from the helper component (Hc-Pro) gene of PRSV-W. Sanger sequencing confirmed that the amplified PCR products for each virus are specific. The sensitivity and specificity of these primers were tested by serial dilution assay of total RNA extracted from virus-infected samples for all three viruses. The detection limit of the Multiplex RT-PCR assay was between 10−5–10−6-fold dilution. The Multiplex RT-PCR assay was successfully applied for the detection of these viruses on 54 field samples, which were collected from two counties of Oklahoma during the 2018 growing season. Based on these results, this Multiplex RT-PCR assay is specific, rapid, and economical for the detection of three common potyviruses of cucurbits and has the potential to screen a large number of field samples of cucurbits against these viruses.

Efecto de inhibidores en el control del Papaya ringspot virus y productividad en papaya (Carica papaya)

La papaya (&lt;em&gt;Carica papaya&lt;/em&gt;) es un frutal muy aceptado en el mercado de exportación por generar alta rentabilidad, en México se cultiva en zonas tropicales y subtropicales. El &lt;em&gt;Papaya ring spot virus&lt;/em&gt; (PRSV) ocasiona la enfermedad más restrictiva de la producción de este cultivo en México y el mundo, por lo cual se evaluó la eficacia de Inhibitovir® y Virus Stop® en campo a 3 mL L-1 y 6 mL L-1 sobre incidencia, intensidad y control de la virosis, altura de planta, diámetro de tallo, número de flores y frutos, peso del fruto y rendimiento. El PRSV se detectó hasta el quinto mes después del trasplante, tiempo para que la plantación lograra un buen amarre de frutos, sin embargo, la eficacia de los inhibidores virales no tuvo diferencias significativas sobre plantas testigo infectadas con el PRSV, así como en altura de planta, diámetro de tallo, número de flores y frutos, peso del fruto y rendimiento.

Molecular diversity of Papaya ringspot virus in India: genetic recombination and mutations between the isolates from different hosts and geo-climatic locations are role players in virus evolution

Among 10 proteins encoded by Papaya ringspot virus (PRSV), only coat protein (CP) has been studied extensively from mainly the papaya-originated isolates i.e. PRSV-P. In this study, besides CP, the helper component proteinase (HC-pro) and nuclear inclusion protein-a (NIa-pro) coding regions from 19 PRSV-P and -W isolates originating from different geo-climatic locations and hosts were analyzed. Unlike CP, both HC-pro and NIa-pro did not reveal the variability in their length. HC-pro and NIa-pro sequences revealed less than 10% deduced amino acid (daa) diversity worldwide, the CP was found highly variable (up to 20% daa diversity). Highest variability in CP sequence was noticed among the cucurbit-originating PRSV-P Indian isolates, especially from Warm semi-arid climate, which was attributed to a large number of aa insertions/deletions. However, papaya-originating PRSV-P isolates from the Oceanic climate were less variable (up to 5% daa diversity). In NIa-pro, besides already known host/pathotype-specific switching of aa Lys/Asp27, switching of Lys27 → Arg27 and Asp27 → Glu27 was identified within P and W pathotypes. Additionally, a novel aa switching from Ser/Met134 → Thr134 between P and W pathotypes respectively was identified. The phylogeny of PRSV isolates was largely based on the geo-climatic locations and hosts. Through recombination detection analysis, three recombinant isolates were detected based on both NIa-pro and CP sequences, which possessed cucurbit-originated PRSV (either -P or -W) isolates as one of their parents (either major or minor.) Patterns of codon usage among the three protein coding sequences generated further revealed that the CP gene is under maximum selection pressure (with six sites) followed by NIa-pro gene (with one site). This investigation shows that the genetic recombination between the isolates originating from different hosts and geo-climatic locations as well as mutations are the significant mechanisms playing their role in generating diverse populations of PRSV.

A new closterovirus in Alcea rosea identified by small RNA deep sequencing

RNA silencing is a conserved and specific degradation mechanism of a target RNA by virus-derived small interfering RNAs in eukaryotic organisms. Identification of viruses of Alcea rosea by small RNA deep sequencing showed the presence of watermelon mosaic virus, malva vein clearing virus, and a putative new closterovirus, which was provisionally named Alcea rosea virus 1 (ArV1). To clarify its taxonomic position, we cloned and analyzed the entire genome of the novel virus. The complete genome of ArV1 has a size of 15318 nt, and contains nine open reading frames (ORFs), namely, a large ORF encoding a putative viral polyprotein 1a (ORF1a), an RNA-dependent RNA polymerase (ORF1b), a p7 (ORF2), a heat shock protein 70 homolog (HSP70h, ORF3), a HSP-90-like protein (ORF4), a coat protein minor (ORF5), a coat protein (ORF6), a p20 (ORF7), and a p21 (ORF8) in the 5′ to 3′ direction. ArV1 shared nucleotide sequence identities of 30.69%–62.62% with 38 other completely sequenced closteroviruses. The amino acid sequence identities between ArV1 and closteroviruses were 34.57%–58.67%. Phylogenetic analysis of HSP70h sequences placed the new virus with members of genus Closterovirus. These results indicate that ArV1 is a member of a new species of the genus Closterovirus.

Papaya Ring Spot Virus (PRSV) as Influenced by the Length of Feeding Time of Aphids (Aphis gossypii)

Background/Objectives: Aphids are known to be great vectors of Papaya Ring Spot Virus and its efficiency in disease transmission was observed based on the length of its feeding time on the healthy papaya plant. Methods/Statistical Analysis: The study was conducted at Bolo Sur, Sipocot, Camarines Sur and Red Lady Variety of Papaya was used as test crop. The study was composed of four treatments: T1 – control (without inoculants), T2 – the PRSV was inoculated for 30 seconds, T3 – 60 seconds and T4 – 90 seconds. The treatments were replicated three times and each replicate was inoculated with 10 aphids as vector. Appearance of symptoms, plant height and number of leaves were assessed for a period of 21 days for each of the treatments. Findings: Results showed that there are no significant differences on plant height among the treatments. However, significant differences on leaf number were observed where the healthy papaya plant had the most number of leaf, however, the length of feeding time of aphids did not had any significant result among the rest of the treatments. Furthermore, Symptoms of PRSV were observed 12 days after inoculation despite the varied feeding time of aphids. Application: Knowledge on the efficacy of PRSV transmission of aphids would be useful in assessing the crops to be grown with papaya and in formulating better fertilization and disease management. Keywords: Aphis gosypii, Carica Papaya, Disease Transmission, Non-persistent Manner, Papaya Ring Spot Virus

EFFECT OF SOME PLANT EXTRACTS AND OTHER COMPOUNDS IN Watermelon mosaic virus (WMV)

ELIZA test using antiserum to Watermelon mosaic virus (WMV) positive reaction with extract from squash plants showing mosaic, blistering and malformation leaves which indicate that the virus under study is WMV, the identification was confirmed by biological assay using quantitative indicator plant Chenopodium amaranticolor which respect chlorotic local lesions. The antibiotic Mitomycin, Para aminophenol, Chenopodium, alcoholic and aquatic extracts of thuja and chenopodium, and alcoholic extract of Eucalyptus at a high conc. showed a high inhibition on WMV in vitro when mixed with disease plant juice directly whereas the lowest inhibition effect resulted when used Bavastin at conc.0.5ml/L (3.8 spot / leaf). The alcoholic extract of Eucalyptus and Para aminophenol showed a high inhibitor effect on WMV in vivo, followed by alcoholic extract of Thuja and aquatic extract of Chenopodium, Bavastin and aquatic extract of Eucalyptus showed restricted effects on virus at 0.5ml /L and 12.5mg / ml respectively,. The higher inhibition of all treatments particularly at a high concentration were compatible with ELISA test results at 405nm.

Occurrence of Watermelon Mosaic Virus in Cucurbita maxima in Poland

Occurrence of Watermelon Mosaic Virus in <i>Cucurbita maxima</i> in Poland

Characterization of a severe isolate of papaya ringspot virus from papaya in western India

Papaya ringspot virus (PRSV), the causative agent of a devastating and widespread ringspot disease in papaya (Carica papaya L.), belongs to the family Potyviridae. Here, we report the first complete genome characterization of a severe PRSV isolate (PRSV-Pune; GenBank accession No. MH311882) from papaya in the Pune district, western India. The genome size of PRSV-Pune is 10,326 nucleotides (nt), excluding the poly-A tail, encoding a polyprotein of 3345 amino acids (aa). The PRSV-Pune showed identity ranging from 82 to 86% and 87–90% at the nucleotide and amino acid levels, respectively, with 29 complete PRSV-P genomes from all over the world. Variations in amino acid composition at and around two polyprotein cleavage sites of PRSV-Pune were observed: MEQY/S instead of MEQY/N in P1/HC-Pro and DYHQ/N instead of VYHQ/S in CI/6K2. Phylogenetic analysis revealed the clustering of PRSV-Pune, along with the majority of Indian PRSV isolates, with isolates of American lineage. Putative recombination events in P1, HC-Pro, CI, NIb and CP coding regions were detected in PRSV-Pune. Negative selection pressure predicted in all cistrons indicates purifying selection. Our results highlight unique attributes of the severe PRSV-Pune from papaya.

Fine mapping of wmv1551, a resistance gene to Watermelon mosaic virus in melon

Recessive resistance to Watermelon mosaic virus (WMV) in melon has previously been reported in the African accession TGR-1551. Using a population of recombinant inbred lines (RIL), derived from a cross between TGR-1551 and the susceptible Spanish cultivar ‘Bola de Oro’ (BO), a major quantitative trait locus (QTL) controlling the resistance was previously mapped to a region of approximately 760 kb in chromosome 11. Minor QTLs were also reported with lower effects, dependent on the environmental conditions. A genotyping by sequencing (GBS) analysis of the RIL population has provided new information that allowed the better location of the major QTL in chromosome 11. Moreover, three minor QTLs in chromosomes 4, 5, and 6 were identified. Generations derived from the RIL population were subsequently phenotyped for resistance and genotyped with SNP markers to fine map the resistance derived from TGR-1551. The results obtained have allowed to narrow the position of the resistance gene on chromosome 11, designated as wmv1551, to a 141-kb region, and the confirmation of a minor QTL in chromosome 5. The effect of the minor QTL in chromosome 5 was significant in heterozygote plants for the introgression in chromosome 11. The SNP markers linked to both QTLs will be useful in breeding programs aimed at the introgression of WMV resistance derived from TGR-1551. Future work will be directed to identifying the resistance gene, wmv1551, in the candidate region on chromosome 11.

Molecular diversity of main cucurbit viruses in Syria

Cucurbits are among the main crops and vegetables grown in Syria, including cucumber (Cucumis sativus), melon (C. melo), watermelon (Citrullus lanatus), and various squash species (Cucurbita pepo, C. moschata, and C. maxima). Cucurbit virus diseases are responsible for significant yield and quality losses to cucurbit crops. In the current study, we investigated the etiology of cucurbit virus diseases, and assessed the molecular diversity of the causal viruses in three major regions of cucurbit production of Syria. Out of 12 viruses and virus groups investigated, zucchini yellow mosaic virus (ZYMV), watermelon mosaic virus (WMV),cucumber mosaic virus (CMV), cucurbit aphid-borne yellows virus (CABYV) and a new member of the genus Polerovirus, pepo aphid-borne yellows virus (PABYV) were detected in various cucurbit crops from plants displaying virus-like symptoms. Syrian ZYMV isolates were closely related and shared low diversity suggesting a relatively recent introduction. A diverse population of WMV with four classical and two emerging isolates of WMV were identified, which complicates the control program. Two CMV isolates were closely related to CMV isolates, reported previously from other crops in the same regions, which may indicate frequent movements of CMV among different hosts. The finding of an isolate of PABYV, a newly described species of the genus Polerovirus, reveals a wider distribution of this virus that may represent a potential emerging problem to cucurbit production.

Studies on molecular variability of coat protein gene of Papaya ringspot virus-P isolates from India

Papaya ringspot virus (PRSV) is the key pathogen responsible for damage of the papaya plant and significant loss of fruit yield globally. Its coat protein (CP) sequences are highly variable and provide adaptability to the virus in the papaya plant. Due to the variability, the major concern facing of papaya cultivation is the breakdown of CP-transgenic PRSV resistance. In this study, 16 PRSV isolates were collected from different locations in seven districts of Uttar Pradesh, India and the variability of the CP gene of the virus was analysed. Further, it was compared with the isolates from other geographical origins. High diversity in CP sequences of our isolates was observed when compared with other Indian isolates. Phylogenetic analysis also revealed that PRSV isolates were more divergent from isolates of other countries. This study of sequence variation in the CP could be further very useful in virus management and development of broad-spectrum virus-resistant transgenic papaya.

Approved genetically modified (GM) horticultural plants: A 25-year perspective

Abstract In this review, we present genetically modified (GM) horticultural events that have passed the regulatory process and have been approved for cultivation or food use in different countries. The first authorization or deregulation of a GM horticultural plant issued 25 years ago initiated a fast expansion of GM organisms (GMO) engineered by using gene transfer technology. The list of GM horticultural species comprises representatives of vegetables, fruit plants and ornamentals. We describe their unique characteristics, often not achievable by conventional breeding, and how they were developed, and the approval process. Information on the adoption of GM horticultural cultivars and sale is accessed if commercialization has occurred. The review comprises, among others, Flavr SavrTM and other tomato cultivars with delayed ripening and improved shelf-life, insect-resistant eggplant (or brinjal), as well as virus-resistant squash, melon and the common bean, and also fruit trees, plum and papaya. Cultivation of the latter was particularly valuable to farmers in Hawaii as it ensured restoration of papaya production devastated earlier by the Papaya ringspot virus (PRSV). In contrast, a plum resistant to sharka (Plum pox virus; PPV) deregulated in the USA is still awaiting commercialization. GM events with improved quality include the recently marketed non-browning apple and high-lycopene pineapple. We also present orange petunia, blue ‘Applause’ rose and Moon-series carnations with a modified purple and violet flower colour. Finally, we discuss prospects of GM horticultural plants, including their development using promising new breeding technologies relying on genome editing and considered as an alternative to the transgenic approach.

Aksaray İli Çerezlik Kabak (Cucurbita pepo L.) Ekim Alanlarında Görülen Bazı Virüs Hastalıkları

Cucurbits (the Cucurbitaceae family) consist of 119 genera and 825 species and are cultivated worldwide, especially in tropical and subtropical regions. Squash (Cucurbita pepo L.), a member of this family, is one of the most cultivated and important vegetable species worldwide. As well as, squash is grown for fresh consuming; its seeds are used as a snack in some Mediterranean countries, Austria, Germany, China and Hungary like in Turkey. One of the most destructive diseases on seed squash is virus diseases in Aksaray province. In this study, it was aimed to determine the virus infections in main squash planting areas in Aksaray. For that purpose, totally 153 plant samples which showing widespread virus symptoms such as curling, mosaic, blistering, mottling, shoe-string, distortion, and stunting were collected from seed squash plants in 2014 and tested by DAS-ELISA method. According to the results of the DAS-ELISA 84.96 % of the samples were infected with Cucumber mosaic cucumovirus (CMV), Papaya ring spot potyvirus - watermelon strain (PRSV-W), Zucchini yellow mosaic potyvirus (ZYMV), Squash mosaic comovirus (SqMV) and Watermelon mosaic potyvirus - 2 (WMV-2). The prevalent virus was ZYMV with the ratio of 66.01 % and followed by WMV-2 with 57.51 %. Besides, double and multiple virus infections were determined commonly in the samples such as, ZYMV+WMV-2, ZYMV+CMV, WMV-2+CMV, ZYMV+SqMV, ZYMV+WMV-2+PRSV-W, and ZYMV+WMV-2+SqMV. Especially, ZYMV+WMV-2 mixed infections were the most common. The infection of Cucumber green mottle mosaic tobamovirus (CGMMV) wasn’t determined in the survey area.

Transcriptome Profile Analysis Reveals that CsTCP14 Induces Susceptibility to Foliage Diseases in Cucumber.

Foliage diseases are prevalent in cucumber production and cause serious yield reduction across the world. Identifying resistance or susceptible genes under foliage-disease stress is essential for breeding resistant varieties, of which leaf-specific expressed susceptible genes are extremely important but rarely studied in crops. This study performed an in-depth mining of public transcriptome data both in different cucumber tissues and under downy mildew (DM) inoculation, and found that the expression of leaf-specific expressed transcription factor CsTCP14 was significantly increased after treatment with DM, as well as being upregulated under stress from another foliage disease, watermelon mosaic virus (WMV), in susceptible cucumbers. Furthermore, the Pearson correlation analysis identified genome-wide co-expressed defense genes with CsTCP14. A potential target CsNBS-LRR gene, Csa6M344280.1, was obtained as obviously reduced and was negatively correlated with the expression of the susceptible gene CsTCP14. Moreover, the interaction experiments of electrophoretic mobility shift assay (EMSA) and yeast one-hybrid assay (Y1H) were successfully executed to prove that CsTCP14 could transcriptionally repress the expression of the CsNBS-LRR gene, Csa6M344280.1, which resulted in inducing susceptibility to foliage diseases in cucumber. As such, we constructed a draft model showing that the leaf-specific expressed gene CsTCP14 was negatively regulating the defense gene Csa6M344280.1 to induce susceptibility to foliage diseases in cucumber. Therefore, this study explored key susceptible genes in response to foliage diseases based on a comprehensive analysis of public transcriptome data and provided an opportunity to breed new varieties that can resist foliage diseases in cucumber, as well as in other crops.

Rapid detection of Cucumber green mottle mosaic virus in watermelon through a recombinase polymerase amplification assay

Cucumber green mottle mosaic virus (CGMMV), a member of the genus Tobamovirus, is an important quarantine plant virus worldwide, and often causes seriously damages to productions of watermelon, melon, cucumber and other cucurbit crops. In this study, we developed a novel isothermal recombinase polymerase amplification (RPA) technique for detection of CGMMV in watermelon samples. A pair of CGMMV specific RPA primers was prepared based on the conserved CGMMV coat protein gene sequences. The result showed that this RPA detection method can be performed at 38 °C and completed in about 30 min, and there was no cross-reactivity with other common cucurbit viruses. Sensitivity assay showed that this RPA method was more sensitive compared with the regular RT-PCR. Using field-collected watermelon tissue samples, we have demonstrated that this newly developed method is rapid, easy to use and reliable for CGMMV detection, especially in resource-limited laboratories or on-site facilities.

The beauties and the bugs: A scenario for designing flower strips adapted to aphid management in melon crops

Flower strips appear to be a promising lever for promoting pest control but a careful selection of the plant species used is needed prior to implementation to avoid possible negative side effects. In the case of open field melon crops, the main pitfall would be to generate aphid and aphid-borne virus reservoirs near the crops. Combining biotests under controlled conditions and data from the literature, we assessed 18 candidate plant species, and ruled-out those posing a potential risk of hosting Aphis gossypii (melon pest and virus vector), Myzus persicae (virus vector) and/or viruses (Cucurbit aphid-borne yellows virus (CABYV), Cucumber mosaic virus (CMV), Watermelon mosaic virus (WMV) and Zucchini yellow mosaic virus (ZYMV)). Five plant species made it through the selection process: cornflower, grass pea, sainfoin, salad burnet and sweet marjoram. Flower strips sown with a mix of these five plant species were evaluated in a five-year field experiment. They displayed a flowering continuum likely to provide a food resource to natural enemies throughout the growing season. Their potential to host natural enemies was compared to those of grass strips and bare soil by monitoring generalist and specialist predators within the different field margins and melon crop. Flower margins supported significantly more of these natural enemies than grass margins and bare soil. All predator taxa analyzed responded positively to the floral resources displayed. Spiders were 3.2 times more abundant in pitfall traps placed in flower margins than in bare soil. Generalist predators and aphid specialist predators collected using a vacuum sampler were 5.5 and 9.1 times more abundant in flower margins than in bare soil, respectively. Interception traps set for weekly periods showed that coccinellid and syrphid fluxes were significantly enhanced near flower margins.

T4 DNA polymerase-assisted upgrade of a nicking/polymerization amplification strategy for ultrasensitive electrochemical detection of Watermelon mosaic virus.

An upgraded nicking/polymerization strategy for ultrasensitive electrochemical detection of Watermelon mosaic virus (WMV) is proposed on the basis of the exonuclease and polymerase activity of T4 DNA polymerase and Mg2+-dependent DNAzyme-assisted and hemin/G-quadruplex DNAzyme-assisted cascade amplification strategies. Briefly, the hybridized DNA of the target WMV sequence, HP1, and P1 was recognized and nicked by nicking endonuclease Nb.BbvCI, and two DNA segments (P1-25 and P1-6) were produced. P1-25 was digested in the 3'→5' direction, and digestion was halted at the 3'-terminal G locus with the exonuclease activity of T4 DNA polymerase. When dNTP solution mix was added to the mixture, an intact enzymatic sequence of Mg2+-dependent DNAzyme was synthesized by T4 DNA polymerase, which hybridized with its substrate sequence in the loop segment of HP2 immobilized on a gold electrode and initiated the cleavage round. The caged G-quadruplex sequence was released and formed hemin/G-quadruplex-based DNAzyme, resulting in sharply increased electrochemical signals. A correlation between the differential pulse voltammetry signal and the concentration of targetWMVsequence was obtained in the range from 50 fM to 1 nM, with 50 fM detection limit. Because the nicking and polymerization reactions are irreversible and share the same buffer, the cascade amplification strategy is an ultrasensitive and high-efficiency strategy, indicating potential for viral detection. Graphical abstract An upgrade nicking/polymerization strategy for ultrasensitive electrochemical detection of Watermelon mosaic virus (WMV) was proposed based on DNAzyme-assistant cascade amplification strategies.

Resistance to the Emerging Moroccan Watermelon Mosaic Virus in Squash.

Moroccan watermelon mosaic virus (MWMV) represents an emerging threat to cucurbit production in the Mediterranean Basin. We sequenced the near complete genome of MWMV-SQ10_1.1, a cloned Spanish isolate. MWMV-SQ10_1.1 has the typical potyvirus genomic structure, and phylogenetic analysis showed that it shared a common ancestor with other Mediterranean MWMV isolates. We used MWMV SQ10_1.1 to inoculate plants in a collection of commercial squash cultivars, including some described as potyvirus resistant. All inoculated plants from all cultivars showed severe infection symptoms. Twenty-four Cucurbita spp. accessions were then tested for their susceptibility to MWMV-SQ10_1.1. Plants of the C. ecuadorensis PI 432441 accession showed no symptoms and their enzyme-linked immunosorbent assay readings were similar to uninfected controls. Progeny analysis of F1 and F2 populations suggested that two recessive genes control PI 432441 resistance to MWMV. We hypothesized that this resistance could be associated with alleles of genes encoding the eukaryotic translation initiation factor 4E (eIF4E), particularly after determination of its recessive nature. A multiple sequence alignment including the two eIF4E ortholog sequences from PI 432441 (CeeIF4E1 and CeeIF4E2) identified three amino acid substitutions in CeeIF4E1 and two amino acid substitutions in CeeIF4E2 potentially involved in potyvirus resistance. Polymerase chain reaction markers for CeeIF4E1 and CeeIF4E2 were developed and used to genotype 156 F2 individuals already phenotyped; this analysis did not support an association of either CeeIF4E2 or CeeIF4E1 with MWMV resistance.