Zucchini Yellow Mosaic Virus Infection Research Articles

Investigates the ability of plant extracts from Lens culinaris to protect zucchini from the Zucchini yellow mosaic virus (ZYMV)

Evaluate the impact of extracts from the Lens culinaris plant on a number of physiological and biochemical parameters in squash leaves infected with ZYMV in this work. Compared to the untreated leaves, ZYMV infected leaves showed a range of symptoms, such as severe mosaic, size reduction, stunting, and deformation. Analysis of physiological data revealed that L. culinaris extract lectin therapies and viral infections had an impact on metabolism. Protein, carbohydrate, and pigment levels were all lowered by viral infection. However, phenolic compounds, total protein, total carbohydrates, total amino acids, proline, total chlorophyll and peroxidases levels are considerably elevated with all extract therapies. The other biochemical parameters also displayed a variety of changes. Moreover shoot length, number of leaves and number of flowers was significantly increased compared to viral control in all treatments. The L. culinaris extract treatment increases the plant’s ZYMV resistance. This is detectable through reduction of the plants treated with lentil lectin pre and post virus inoculation, reduction in disease severity and viral concentration, and percentage of the infected plants has a virus. All findings demonstrate significant metabolic alterations brought by viral infections or L. culinaris extract treatments, and they also suggest that exogenous extract treatments is essential for activating the body’s defences against ZYMV infection.

Attenuation of Zucchini mosaic virus disease in cucumber plants by mycorrhizal symbiosis

Key messageArbuscular mycorrhizal fungi generated systemic acquired resistance in cucumber to Zucchini yellow mosaic virus, indicating their prospective application in the soil as a sustainable, environmentally friendly approach to inhibit the spread of pathogens.The wide spread of plant pathogens affects the whole world, causing several plant diseases and threatening national food security as it disrupts the quantity and quality of economically important crops. Recently, environmentally acceptable mitigating practices have been required for sustainable agriculture, restricting the use of chemical fertilizers in agricultural areas. Herein, the biological control of Zucchini yellow mosaic virus (ZYMV) in cucumber (Cucumis sativus L.) plants using arbuscular mycorrhizal (AM) fungi was investigated. Compared to control plants, ZYMV-infected plants displayed high disease incidence (DI) and severity (DS) with various symptoms, including severe yellow mosaic, mottling and green blisters of leaves. However, AM fungal inoculation exhibited 50% inhibition for these symptoms and limited DS to 26% as compared to non-colonized ones. The detection of ZYMV by the Enzyme-Linked Immunosorbent Assay technique exhibited a significant reduction in AM-inoculated plants (5.23-fold) compared with non-colonized ones. Besides, mycorrhizal root colonization (F%) was slightly reduced by ZYMV infection. ZYMV infection decreased all growth parameters and pigment fractions and increased the malondialdehyde (MDA) content, however, these parameters were significantly enhanced and the MDA content was decreased by AM fungal colonization. Also, the protein, proline and antioxidant enzymes (POX and CAT) were increased with ZYMV infection with more enhancements due to AM root colonization. Remarkably, defence pathogenesis-related (PR) genes such as PR-a, PR-b, and PR-10 were quickly expressed in response to AM treatment. Our findings demonstrated the beneficial function of AM fungi in triggering the plant defence against ZYMV as they caused systemic acquired resistance in cucumber plants and supported their potential use in the soil as an environment-friendly method of hindering the spread of pathogenic microorganisms sustainably.

Antiviral activities of three Streptomyces spp. against Zucchini yellow mosaic virus (ZYMV) infecting squash (Cucurbita pepo L.) plants

BackgroundZucchini yellow mosaic virus (ZYMV) is the major devastating disease worldwide, which leads to substantial economic losses (up to 100%) to yield and fruits quality produced of squash plants. Application of agro-pesticides is efficient and incompatible with organic agriculture and reportedly has harmful effects on human health and ecosystem. Nowadays, Streptomyces spp., a rich source of potential bioactive secondary metabolites, is extensively used to manage various biotic stresses for sustainable agriculture and considered to be eco-friendly.ResultsAn isolate of ZYMV was isolated from squash plants and identified based on biological and molecular characterization using RT-PCR for several genes, i.e., coat protein gene (CP), DAG, P1 and P3 coding regions in the virus RNA, and then, nucleotide sequences were compared to other isolates submitted in GenBank having accession numbers, i.e., OM925548.1, OM925549.1, OM925550.1 and OM925551.1, respectively. Phylogenetic trees of CP, DAG, P1 and P3 sequences compared to other ZYMV nucleotide sequences presented in the GenBank. In order to determine new efficient substances elicitors derived from Streptomyces spp. to control ZYMV, greenhouse trials were designed with seven treatments including culture broth of three Streptomyces spp. (S. sampsonii, S. rochei and S. griseus) individually or in combinations. Early application of Streptomyces spp. revealed potent antiviral activity against ZYMV infection, inhibited virus replication and promoted plant growth as well as induced systemic resistance. Moreover, physiological stress markers as indicators for systemic acquired resistance were distinguished via significantly enhanced proline, phenols and defense-related enzymes, i.e., catalase, superoxide dismutase and glutathione peroxidase by culture broth treatments, despite the presence of infection. Real-time qPCR assay was a more reliable and accurate detection for quantification ZYMV than conventional PCR. The results revealed that the three Streptomyces spp. novel biocontrol agents produced Behenic alcohol (Docosanol) which provided clues to be potential antiviral mechanisms capable to down-regulate P1 gene expression responsible for virus replication and movement from cell to cell to induce systemic infection as well as safe eco-friendly candidates for the controlling approaches against plant viral pathogens.ConclusionResults suggest that the three Streptomyces spp. provided clues as a novel biocontrol agent having potential antiviral with protective activity and eco-friendly alternative pesticides for managing plant viruses.

High impact of Clerodendrum paniculatum leaf extract to suppress zucchini yellow mosaic virus infection in zucchini plants

Abstract. Pandawani NP, Listihani L, Widnyana IK, Ariati PEP, Selangga DGW. 2022. High impact of Clerodendrum paniculatum leaf extract to suppress zucchini yellow mosaic virus infection in zucchini plants. Biodiversitas 23: 2914-2919. Zucchini yellow mosaic virus (ZYMV) is an important virus in zucchini plants (Cucurbita pepo L.). ZYMV infection is prevalent in C. pepo in Bali and is extremely difficult to eradicate. This study aimed to determine the efficacy of pagoda leaf extract (Clerodendrum paniculatum L.) in reducing yield loss in C. pepo. A factorial randomized block design with two variables was employed in this study. The application time of the C. paniculatum extract was the first variable, and concentration was the second. Plant extract was applied during seed immersion, one day before and after inoculation, and on the same day of virus inoculation. The concentrations of C. paniculatum extract employed were 10%, 30%, and 50%. The crude extract was sprayed onto the C. pepo leaves. Plants treated with extract one day after virus inoculation at 10%, 30%, and 50% concentrations exhibited yellowing, yellowing with cupping, mosaic, mosaic with cupping, and stunting. While application of extract one day before virus inoculation at 30% and 50% concentrations resulted in yellowing and yellowing with cupping signs. Plants infected with ZYMV first showed flowering at 37 DAP, whereas plants treated with C. paniculatum leaf extract one day before virus inoculation started flowering at 32 DAP. Application of C. paniculatum leaf extract one day before ZYMV inoculation on C. pepo effectively suppressed 40% yield loss. The findings of present investigation revealed information about the potential of C. paniculatum leaf extract as a plant virus control agent through the mechanism of induction in C. pepo.

Development of Bottle Gourd Lines Resistant to Zucchini Yellow Mosaic Virus Using Ethyl Methanesulfonate Mutagenesis

Zucchini yellow mosaic virus (ZYMV) causes serious damage to cucurbit crops worldwide and can be spread by aphids, by mechanical injury, and in seeds. With the popularization of cucurbit grafting, the use of susceptible rootstock has increased the risk of ZYMV infection in cucurbit crops. In China, the bottle gourd (Lagenaria siceraria) is a widely used rootstock in grafted watermelon production. However, few resistant bottle gourds are available commercially. This study developed bottle gourd lines resistant to ZYMV using ethyl methanesulfonate (EMS) mutagenesis. A new mutated bottle gourd population (M1) was generated by treating seeds with EMS. Diverse phenotypes were observed in the seedlings, flowers, and fruit of M2 plants, some of which are of potential commercial interest, such as dwarfing and different fruit shapes. Based on the M2 phenotypes, 106 M3 lines were selected and screened for resistance to ZYMV by mechanical inoculation and agroinfiltration. Nine M3 lines were resistant to ZYMV during three tests. One inbred M4 line (177-8) was developed and showed stable resistance and no virus when tested using a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and polymerase chain reaction. These resistant lines are promising materials for developing watermelon rootstock and exploring resistance genes as new ZYMV-resistant resources. EMS induction could be a practical strategy for creating resistant cucurbit crops.

English

In the present study, fifteen cucumber genotypes were screened against Zucchini yellow mosaic virus (ZYMV) and root-knot nematode (Meloidogyne incognita) individually and in combinations. All the cucumber genotypes behaved differently regarding root and shoot lengths and weights, number of galls, eggmasses and ZYMV infection when inoculated with M. incognita and ZYMV alone and in combinations. None of the fifteen cucumber genotypes was found immune, highly or moderately resistant to M. incognita. Two genotypes viz., Alpha Prime and Patio were found resistant to the nematode. Contrarily, Max Pack and Beti-alpha were highly susceptible as evident by maximum galls on their roots and reductions in growth variables. Similarly, the genotypes Best PIC, Songrooh, Northern Pack, C-7 and C-5 appeared as moderately susceptible whereas Shaheen, Jakson, C-1, C-2, C-3 and C-9 genotypes showed susceptible reactions to the nematode alone. Similar trend was noticed when the genotypes were inoculated with both the nematode and the virus. Similarly, on the basis of disease rating scale, two genotypes viz., Alpha Prime and Patio were grouped as moderately resistant to ZYMV. On the other hand, eleven genotypes viz., Max Pack, Shaheen, Songrooh, Northern Pack, Jakson, Beti-alpha, C-1, C-2, C-3, C-5 and C-9 were catalogued as highly resistant while two genotypes Best PIC and C-7 were categorized as susceptible against ZYMV alone. Similarly, all the genotypes behaved in the same way when inoculated with M. incognita. Two genotypes Alpha Prime and Patio were found resistant against both the pathogens inoculated simultaneously and hence are recommended for cultivation. © 2021 Friends Science Publishers

Endemic Atlantic Forest species of Caryophyllales as inhibitors of viral infection in zucchini

ABSTRACT In Brazil, zucchini (Cucurbita pepo) is a socioeconomically important vegetable affected by damage caused primarily by zucchini yellow mosaic virus (ZYMV). Although the occurrence of cucumber mosaic virus (CMV) is less frequent, in C. pepo ‘Caserta’ plants it can cause symptoms such as mottle, mosaic, leaf and fruit distortion, as well as reduced plant development. To minimize the damage, the most widely used management technique is the preventive, albeit inefficient, application of insecticides, aimed at controlling aphids, the vectors of this virus. Thus, the search for more effective and less environmentally harmful control methods has been the target of investigations. The purpose of the present study was to assess the action of the extracts of four native Caryophyllales species, as inhibitors of infection by CMV and ZYMV in C. pepo, in addition to evaluating the possible induced resistance in this species. Fresh leaf extracts (LEs) of Guapira opposita, Pisonia ambigua (Nyctaginaceae), Gallesia integrifolia and Seguieria langsdorffii (Phytolaccaceae), previously assessed in the tobacco mosaic virus / Nicotiana glutinosa pathosystem, were submitted to progressive dilutions sprayed on cotyledonary C. pepo leaves 30 min before inoculation with CMV and ZYMV. Leaf extracts of G. integrifolia did not induce inhibition in any of the pathosystems assessed. Guapira opposita LEs inhibited the infection of plants inoculated with ZYMV below 50% but inhibited CMV infection by 70% at a concentration of 1:40. Given that leaf extracts of P. ambigua and S. langsdorffii induced high percentage inhibition, evident in the number of asymptomatic plants and confirmed by serological tests, these species were selected to assess induced resistance in pre-treatment experiments. The LEs were efficient in inhibiting ZYMV and CMV infection in C. pepo when applied up to 48 h before inoculation. The LEs of S. langsdorffii and G. opposita, also tested for this system, were efficient when applied up to 72 h before CMV inoculation. The LEs can be prepared from dry leaves and maintained at -20°C for at least three years, conserving their inhibitory activity. These results expand the possibilities for producers and consumers alike in the sustainable management of the main zucchini viruses, without damaging the environment.

Epidemiology of Zucchini yellow mosaic virus in cucurbit crops in a remote tropical environment

In the remote Ord River Irrigation Area (ORIA) in tropical northwest Australia, severe Zucchini yellow mosaic virus (ZYMV) epidemics threaten dry season (April-October) cucurbit crops. In 2016–2017, wet season (November-March) sampling studies found a low incidence ZYMV infection in wild Cucumis melo and Citrullus lanatus var. citroides plants, and both volunteer and garden crop cucurbits. Such infections enable its persistence in the wet season, and act as reservoirs for its spread to commercial cucurbit crops during the dry season. Tests on 1019 samples belonging to 55 species from 23 non-cucurbitaceous plant families failed to detect ZYMV. It was also absent from wild cucurbit weeds within sandalwood plantations. The transmission efficiencies of a local isolate by five aphid species found in the ORIA were: 10 % (Aphis craccivora), 7% (A. gossypii), 4% (A. nerii), and 0% (Rhopalosiphum maidis and Hysteroneura setariae). In 2016–2017, in all-year-round trapping at five representative sites, numbers of winged aphids caught were greatest in July-August (i.e. mid growing season) but varied widely between trap sites reflecting local aphid host abundance and year. Apart from one localised exception in 2017, flying aphid numbers caught and ZYMV spread in data collection blocks during 2015–2017 resembled what occurred commercial cucurbit crops. When ZYMV spread from external infection sources into melon blocks, its predominant spread pattern consisted of 1 or 2 plant infection foci often occurring at their margins. In addition, when plants of 29 cucurbit cultivars were inoculated with an ORIA isolate and two other ZYMV isolates and the phenotypes elicited were compared, they resembled each other in overall virulence. However, depending upon isolate-cultivar combination, differences in symptom expression and severity occurred, and one isolate caused a systemic hypersensitive phenotype in honeydew melon cvs Estilo and Whitehaven. When the new genomic RNA sequences of 19 Australian isolates were analysed, all seven ORIA isolates fitted within ZYMV phylogroup B, which also included two from southwest Australia, whereas the remaining 10 isolates were all within minor phylogroups A–I or A–II. Based on previous research and the additional knowledge of ZYMV epidemic drivers established here, an integrated disease management strategy targeting ZYMV spread was devised for the ORIA’s cucurbit industry.

Detection of disease in Cucurbita maxima Duch. ex Lam. caused by a mixed infection of Zucchini yellow mosaic virus, Watermelon mosaic virus, and Cucumber mosaic virus in Southeast China using a novel small RNA sequencing method.

The genus Cucurbita comprises many popular vegetable and ornamental plants, including pumpkins, squashes, and gourds, that are highly valued in China as well as in many other countries. During a survey conducted in Zhejiang province, Southeast China in 2016, severe symptoms of viral infection were observed on Cucurbita maxima Duch. ex Lam. Diseased plants showed symptoms such as stunting, mosaicking, Shoe string, blistering, yellowing, leaf deformation, and fruit distortion. Approximately, 50% of Cucurbita crops produced in Jinhua were diseased, causing an estimated yield loss of 35%. In this study, we developed a method using all known virus genomes from the NCBI database as a reference to map small RNAs to develop a diagnostic tool that could be used to diagnose virus diseases of C. maxima. 25 leaf samples from different symptomatic plants and 25 leaf samples from non-symptomatic plants were collected from the experimental field of Jihua National Agricultural Technology Garden for pathogen identification. Small RNAs from each set of three symptomatic and non-symptomatic samples were extracted and sequenced by Illumina sequencing. Twenty-four different viruses were detected in total. However, the majority of the small RNAs were from Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV), and Cucumber mosaic virus (CMV). Mixed infections of these three viruses were diagnosed in leaf samples from diseased plants and confirmed by reverse transcription PCR (RT-PCR) using primers specific to these three viruses. Crude sap extract from symptomatic leaf samples was mechanically inoculated back into healthy C. maxima plants growing under greenhouse conditions. Inoculated plants developed the same disease symptoms as those observed in the diseased plants and a mixed infection of ZYMV, WMV, and CMV was detected again by RT-PCR, thus fulfilling Koch’s postulates. The diagnostic method developed in this study involves fewer bioinformatics processes than other diagnostic methods, does not require complex settings for bioinformatics parameters, provides a high level of sensitivity to rapidly diagnose plant samples with symptoms of virus diseases and can be performed cheaply. This method therefore has the potential to be widely applied as a diagnostic tool for viruses that have genome information in the NCBI database.

Evaluation of genotoxicity of the aqueous extracts from wild Artemisia herba-alba and Jasmina montana against Zucchini yellow mosaic virus (ZYMV) in Cucurbita pepo plants

Squash or cucurbit (Cucurbita pepo) is one of the famous and important vegetable plants in most world countries. The squash is infected by the critical Zucchini yellow mosaic virus (ZYMV) in Egypt. Though pesticides can protect the plants of pest infections, there are no effective compounds that can be applied as virucides. In this work, the effects of aqueous extracts from Jasmina montana and Artemisia herba-alba on ZYMV infection in the squash plants were examined. In addition, SDS-PAGE protein patterns and enzyme activities were evaluated and induction of resistance by plant elicitors against ZYMV was studied The results observed that using of the aqueous extracts from A. herba-alba or J. montana extracts prior to ZYMV inoculation recorded 100% inhibition of virus infection. Also, complete inhibition was obtained by treatment of A. herba-alba extract with the virus inoculum led to destroy the virus particles due to presence of the effective compounds (terpens, phenolics and the essential oils) in the plant extract. SDS-PAGE protein profiles and enzyme activities were studied in treated and untreated plants. Genomic DNA variation was studied using random amplified polymorphic DNA (RAPD) and Inter-simple sequence repeat (ISSR) loci. The alterations in RAPD and ISSR assays of representative squash plants can be applied to comprehend of induced systemic resistance. These inducers stimulated resistance in the squash plants. Therefore, elicitors should be taken into consideration in the breeding programs for ZYMV control.

Zucchini Yellow Mosaic Virus Infection Limits Establishment and Severity of Powdery Mildew in Wild Populations of Cucurbita pepo.

Few studies have examined the combined effect of multiple parasites on host fitness. Previous work in the Cucurbita pepo pathosystem indicates that infection with Zucchini yellow mosaic virus (ZYMV) reduces exposure to a second insect-vectored parasite (Erwinia tracheiphila). In this study, we performed two large-scale field experiments employing wild gourds (Cucurbita pepo ssp. texana), including plants with a highly introgressed transgene conferring resistance to ZYMV, to examine the interaction of ZYMV and powdery mildew, a common fungal disease. We found that ZYMV-infected plants are more resistant to powdery mildew (i.e., less likely to experience powdery mildew infection and when infected with powdery mildew, have reduced severity of powdery mildew symptoms). As a consequence, during widespread viral epidemics, proportionally more transgenic plants get powdery mildew than non-transgenic plants, potentially mitigating the benefits of the transgene. A greenhouse study using ZYMV-inoculated and non-inoculated controls (non-transgenic plants) revealed that ZYMV-infected plants were more resistant to powdery mildew than controls, suggesting that the transgene itself had no direct effect on the powdery mildew resistance in our field study. Additionally, we found evidence of elevated levels of salicylic acid, a phytohormone that mediates anti-pathogen defenses, in ZYMV-infected plants, suggesting that viral infection induces a plant immune response (systemic acquired resistance), thereby reducing plant susceptibility to powdery mildew infection.

Cotton Aphid (Aphis gossypii Glover) and Green Peach Aphid (Myzus persicae Sulzer) Efficiency of Zucchini Yellow Mosaic Virus Potyvirus (ZYMV) transmission on Squash Plants At Fayoum Governorate.

Zucchiniyellow mosaic virus (ZYMV) is an important non- persistent virus causing high squashproduction losses in Egypt. Aphis gossypii Glover and Myzus persicaeSulazer insects have high efficiency of ZYMV transmission from infected squashplants to healthy ones in Egypt,in advance of their rapid spreading. ZYMV was isolated fromnaturally infected squash plants collected from two locations (Sennoris &Fayoum), at Fayoum governorate. Virus identification was done byserological tests (ELISA) using four different antiserums. Virus wastransmitted to healthy squash plants by mechanical transmission and by using thetwo aphid insects. Fecundity and life span of two aphids andforms (alate and apterous) were studied. ELISA test had relay that the viruswas ZYMV. Typical symptoms of virus were observed by mechanical and aphidinsect's inoculation,yellowmosaic, necrosis, leaf curling, blisters stunting, deformation, reduction inleaf size and knobbed fruits (sever malformation).Fecundity and life span ofAphis gossypii were higher than thoseof Myzus persicae on infectedsquash plantscompared with healthy, respectively.The reducing aphid insects population isrecommended in order to decreasing losses caused by ZYMV infection (as theirability of transmission), in addition of removing the infected plantscontinuously which considered as a source if virus inoculum

Pokeweed (Phytolacca americana L.) antiviral protein inhibits Zucchini yellow mosaic virus infection in a dose-dependent manner in squash plants

Pokeweed antiviral protein (PAP) of Phytolacca americana L. (pokeweed) is a single-chain ribosome-inactivating protein (RIP) characterized by its ability to depurinate plant ribosomes. Here, we isolated, cloned, and expressed the ribosome inactivating protein (RIP) gene, designated as pokeweed antiviral protein type 1 (PAP I), from the summer leaves of pokeweed collected from the Black Sea region (Turkey). Our findings presented here provide direct evidence that exogenous application of PAP I causes concentration-dependent inhibition of Zucchini yellow mosaic virus (ZYMV) infection on squash plants. Squash plants were exposed to PAP I protein with and without DMSO for four consecutive days. Regular spraying of approximately 30 kDa recombinant PAP I at 2 µg mL?1 concentration prevented treated plants from mechanical virus infection. PAP I showed antiviral activity in 9 plants out of 15 inoculated plants. Remarkably, simultaneous application of PAP, DMSO, and ZYMV did not prevent virus infection, suggesting that PAP did not have any effect on viral RNA. In the absence of ZYMV the purified peptide was not cytotoxic for squash plants, although a reduction of plant size, possibly caused by host ribosome depurination, was observed.

Dicer-Like 4 Is Involved in Restricting the Systemic Movement of Zucchini yellow mosaic virus in Nicotiana benthamiana.

Zucchini yellow mosaic virus (ZYMV) induces serious diseases in cucurbits. To create a tool to screen for resistance genes, we cloned a wild ZYMV isolate and inserted the visual marker Rosea1 to obtain recombinant clone ZYMV-Ros1. While in some plant-virus combinations Rosea1 induces accumulation of anthocyanins in infected tissues, ZYMV-Ros1 infection of cucurbits did not lead to detectable anthocyanin accumulation. However, the recombinant virus did induce dark red pigmentation in infected tissues of the model plant Nicotiana benthamiana. In this species, ZYMV-Ros1 multiplied efficiently in local inoculated tissue but only a few progeny particles established infection foci in upper leaves. We used this system to analyze the roles of Dicer-like (DCL) genes, core components of plant antiviral RNA silencing pathways, in ZYMV infection. ZYMV-Ros1 local replication was not significantly affected in single DCL knockdown lines nor in double DCL2/4 and triple DCL2/3/4 knockdown lines. ZYMV-Ros1 systemic accumulation was not affected in knockdown lines DCL1, DCL2, and DCL3. However in DCL4 and also in DCL2/4 and DCL2/3/4 knockdown lines, ZYMV-Ros1 systemic accumulation dramatically increased, which highlights the key role of DCL4 in restricting virus systemic movement. The effect of DCL4 on ZYMV systemic movement was confirmed with a wild-type version of the virus.

Vertical infection of Zucchini yellow mosaic virus via pollen transmission occurs at a lower frequency than ovule transmission

Seed transmission of Zucchini yellow mosaic virus (ZYMV) has been demonstrated in a variety of cucurbits, including wild Cucurbita species, and pollen transmission of viruses is common in the family Potyviridae. Consequently, vertical transmission of ZYMV may occur via the pollen of infected wild squash as opposed to ovule transmission. To determine if vertical infection of ZYMV occurs via pollen transmission, we pollinated flowers on virus-free Cucurbita pepo ssp. texana plants with pollen from ZYMV infected plants. We found that seed infection of ZYMV via pollen occurs at a rate of 0.13 %. This rate is much lower than expected based on previously reported rates of seed transmission, which suggests that while seed transmission via pollen does occur in C. pepo, it is not the main mechanism for vertical infection. Because seed transmission of ZYMV has been shown in virus-resistant transgenic plants, it is possible that ZYMV infection of transgenic plants via pollen may contribute to the seed transmission and geographic distribution of this virus.

Partially resistant Cucurbita pepo showed late onset of the Zucchini yellow mosaic virus infection due to rapid activation of defense mechanisms as compared to susceptible cultivar.

Zucchini yellow mosaic virus (ZYMV) is an emerging viral pathogen in cucurbit-growing areas wordwide. Infection causes significant yield losses in several species of the family Cucurbitaceae. To identify proteins potentially involved with resistance toward infection by the severe ZYMV-H isolate, two Cucurbita pepo cultivars (Zelena susceptible and Jaguar partially resistant) were analyzed using a two-dimensional gel electrophoresis-based proteomic approach. Initial symptoms on leaves (clearing veins) developed 6–7 days post-inoculation (dpi) in the susceptible C. pepo cv. Zelena. In contrast, similar symptoms appeared on the leaves of partially resistant C. pepo cv. Jaguar only after 15 dpi. This finding was confirmed by immune-blot analysis which showed higher levels of viral proteins at 6 dpi in the susceptible cultivar. Leaf proteome analyses revealed 28 and 31 spots differentially abundant between cultivars at 6 and 15 dpi, respectively. The variance early in infection can be attributed to a rapid activation of proteins involved with redox homeostasis in the partially resistant cultivar. Changes in the proteome of the susceptible cultivar are related to the cytoskeleton and photosynthesis.

Bahasa Indonesia

Infection of viruses on Cucurbitaceae may cause high yield and economic losses. Squash mosaic virus is a seed borne virus and among the most important virus infecting Cucurbitaceae. The aims of these research was to detect infection of several viruses on Cucurbitaceae and to examine seed transmission efficiency of SqMV. Detection of Cucumber mosaic virus (CMV), Squash mosaic virus (SqMV), Watermelon mosaic virus-2 (WMV-2), Zucchini yellow mosaic virus (ZYMV), and Tobacco ringspot virus (TRSV) from field samples and seeds was conducted using Indirect-ELISA method. Infection of CMV, SqMV and ZYMV was detected from field samples. Seed transmission of SqMV on commercial seeds of bottle gourd, watermelon, zucchini, cabocha, cucumber, and melon was 13, 13, 33, 73, 100, and 100%, respectively. Seed transmission of ZYMV was only occurred on bottle gourd and zucchini, i.e. 13.3% and 26.67%, respectively. Infection of SqMV through F2 seed was determined from cucumber, bottle gourd, and melon, i.e. 93, 100, and 100%, respectively. Therefore, the status of SqMV as quarantine pest should be evaluated since SqMV was already found in West Java.

Disease Interactions in a Shared Host Plant: Effects of Pre-Existing Viral Infection on Cucurbit Plant Defense Responses and Resistance to Bacterial Wilt Disease

Both biotic and abiotic stressors can elicit broad-spectrum plant resistance against subsequent pathogen challenges. However, we currently have little understanding of how such effects influence broader aspects of disease ecology and epidemiology in natural environments where plants interact with multiple antagonists simultaneously. In previous work, we have shown that healthy wild gourd plants (Cucurbita pepo ssp. texana) contract a fatal bacterial wilt infection (caused by Erwinia tracheiphila) at significantly higher rates than plants infected with Zucchini yellow mosaic virus (ZYMV). We recently reported evidence that this pattern is explained, at least in part, by reduced visitation of ZYMV-infected plants by the cucumber beetle vectors of E. tracheiphila. Here we examine whether ZYMV-infection may also directly elicit plant resistance to subsequent E. tracheiphila infection. In laboratory studies, we assayed the induction of key phytohormones (SA and JA) in single and mixed infections of these pathogens, as well as in response to the feeding of A. vittatum cucumber beetles on healthy and infected plants. We also tracked the incidence and progression of wilt disease symptoms in plants with prior ZYMV infections. Our results indicate that ZYMV-infection slightly delays the progression of wilt symptoms, but does not significantly reduce E. tracheiphila infection success. This observation supports the hypothesis that reduced rates of wilt disease in ZYMV-infected plants reflect reduced visitation by beetle vectors. We also documented consistently strong SA responses to ZYMV infection, but limited responses to E. tracheiphila in the absence of ZYMV, suggesting that the latter pathogen may effectively evade or suppress plant defenses, although we observed no evidence of antagonistic cross-talk between SA and JA signaling pathways. We did, however, document effects of E. tracheiphila on induced responses to herbivory that may influence host-plant quality for (and hence pathogen acquisition by) cucumber beetles.

Non-persistently aphid-borne viruses infecting pumpkin and squash in Serbia and partial characterization of Zucchini yellow mosaic virus isolates

Cucurbit species grown in the Vojvodina Province, Serbia, were surveyed for the incidence of Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV), Cucumber mosaic virus (CMV), Squash mosaic virus (SqMV), Papaya ringspot virus (PRSV) and Tobacco ringspot virus (TRSV) from 2007 to 2009. Samples from more than 700 pumpkin, squash and bottle gourd plants with virus-like symptoms were analyzed by double-antibody sandwich (DAS)-ELISA. ZYMV, WMV and CMV were detected in 79.2, 32.2, and 12.8% of tested samples, respectively. WMV was prevalent in 2007 and ZYMV in 2008–09. Mixed infections were the most frequent type in 2007–08 in contrast to 2009 when single infection of ZYMV prevailed. ZYMV was the most widespread being found in 33 out of 39 inspected fields. Virus species identification was confirmed in selected samples by conventional reverse transcription-polymerase chain reaction (RT-PCR) and sequencing of their coat protein genes. By comparing the obtained virus isolate sequences with those available in GenBank, the identification of serologically detected viruses was confirmed. Phylogenetic analysis based on complete coat protein (CP) sequences highlighted that Serbian ZYMV isolates were closely related to other Central European ZYMV isolates. Finally, additional testing of ELISA-negative samples by RT-PCR using primers specific to six other mosaic viruses revealed the presence of Tomato spotted wilt virus (TSWV) in winter (Cucurbita maxima) and summer (C. pepo ‘Beogradska’) squash. This is the first report of TSWV natural occurrence on cucurbits in Serbia and on winter squash worldwide.

First Report of Zucchini yellow mosaic virus in Watermelon in Serbia.

During a survey of cucurbit viruses in the Gornji Tavankut locality (North Backa District), Serbia in June 2011, field-grown (a surface of 1.8 ha) watermelon plants (Citrullus lanatus [Thunb.] Matsum and Nakai) with mild mosaic symptoms were observed. Large numbers of Aphis gossypii were colonizing the crop. A total of 26 samples, six from plants exhibiting mosaic and 20 from asymptomatic plants, were analyzed by double-antibody sandwich-ELISA using polyclonal antisera virus (Bioreba AG, Reinach, Switzerland) against three cucurbit-infecting viruses known to infect Cucurbita pepo in Serbia: Zucchini yellow mosaic virus (ZYMV), Cucumber mosaic virus, and Watermelon mosaic virus (3). Commercial positive and negative controls were included in ELISA analysis. Only six symptomatic samples tested positive for ZYMV, but no other tested viruses were found. The virus was mechanically transmitted from a representative ELISA-positive watermelon sample (550-11) to five plants of C. pepo 'Ezra F1' and severe mosaic was noticed 10 days after inoculation. For further confirmation of ZYMV infection, total RNA from a naturally infected watermelon plant and symptomatic C. pepo 'Ezra F1' plants were extracted with the RNeasy Plant Mini Kit (Qiagen, Hilden, Germany). Reverse transcription (RT)-PCR was performed with the One-Step RT-PCR Kit (Qiagen) using primer pair ZY-2 and ZY-3 (2). Total RNA obtained from a Serbian isolate of ZYMV from pumpkin (GenBank Accession No. HM072432) and healthy watermelon plants were used as positive and negative controls, respectively. The expected sizes of the RT-PCR products (1,186 bp) were amplified from naturally and mechanically infected symptomatic samples, but not from healthy tissues. The amplified product that derived from isolate 550-11 was purified (QIAquick PCR Purification Kit, Qiagen), sequenced in both directions, deposited in GenBank (Accession No. JN561294), and subjected to sequence analysis using MEGA4 software. Sequence comparisons revealed a high nucleotide identity of 99.9 to 99.8% and 100 to 99.6% amino acid identity for the CP gene with Serbian ZYMV isolates from C. pepo (Accession Nos. JF308188, HM072431, and HM072432). The nucleotide and deduced amino acid sequences of the entire CP gene (837 nt) of the Serbian ZYMV isolate from watermelon shared 99.9 to 93.7% and 100 to 96.8% identity, respectively, with innumerous isolates of ZYMV deposited in the GenBank (e.g., Accession Nos. AJ420012-17 and FJ705262). To our knowledge, this is the first report of ZYMV spreading its host range to watermelon in Serbia. ZYMV infection has been responsible for severe epidemics on cucurbits throughout the world (1). The presence of ZYMV on watermelon could therefore represent a serious threat for this valuable crop in Serbia, especially considering that it is prevalent in other cucurbit crops in the country and the vectors are widespread.