Zucchini Yellow Mosaic Virus Isolates Research Articles

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.

Zucchini Yellow Mosaic Virus (ZYMV) as a Serious Biotic Stress to Cucurbits: Prevalence, Diversity, and Its Implications for Crop Sustainability.

Zucchini yellow mosaic virus (ZYMV) is a severe threat to cucurbit crops worldwide, including Pakistan. This study was pursued to evaluate the prevalence, geographic distribution, and molecular diversity of ZYMV isolates infecting cucurbits in Pakistan's Pothwar region. Almost all the plant viruses act as a biotic stress on the host plants, which results in a yield loss. These viruses cause losses in single-infection or in mixed-infection cucurbit crops, and we have found a number of mixed-infected samples belonging to the Curubitaceae family. Serological detection of the tested potyviruses in the collected cucurbit samples revealed that ZYMV was the most prevalent virus, with a disease incidence (DI) at 35.2%, followed by Papaya ringspot virus (PRSV) with an incidence of 2.2%, and Watermelon mosaic virus (WMV) having an incidence as little as 0.5% in 2016. In the year 2017, a relatively higher disease incidence of 39.7%, 2.4%, and 0.3% for ZYMV, WMV, and PRSV, respectively, was recorded. ZYMV was the most prevalent virus with the highest incidence in Attock, Rawalpindi, and Islamabad, while PRSV was observed to be the highest in Islamabad and Jhelum. WMV infection was observed only in Rawalpindi and Chakwal. Newly detected Pakistani ZYMV isolates shared 95.8-97.0% nucleotide identities among themselves and 77.1-97.8% with other isolates retrieved from GenBank. Phylogenetic relationships obtained using different ZYMV isolates retrieved from GenBank and validated by in silico restriction analysis revealed that four Pakistani isolates clustered with other ZYMV isolates in group IIb with Chinese, Italian, Polish, and French isolates, while another isolate (MK848239) formed a separate minor clade within IIb. The isolate MK8482490, reported to infect bitter gourd in Pakistan, shared a minor clade with a Chinese isolate (KX884570). Recombination analysis revealed that the recently found ZYMV isolate (MK848239) is most likely a recombinant of Pakistani (MK848237) and Italian (MK956829) isolates, with a recombinant breakpoint between 266 and 814 nucleotide positions. Local isolate comparison and recombination detection may aid in the development of a breeding program that identifies resistant sources against recombinant isolates because the ZYMV is prevalent in a few cucurbit species grown in the surveyed areas and causes heavy losses and economic damage to the agricultural community.

First report of zucchini yellow mosaic virus infecting bitter melon (Momordica charantia) in South Korea.

Bitter melon (Momordica charantia L., family Cucurbitaceae) is used in traditional medicine for diabetes, cancer, and inflammation-associated diseases due to bioactive compounds in Asia and tropical Africa (Bortolotti et al. 2019). In July 2021, approximately 10% of bitter melon plants in the field showed symptoms such as mosaic, yellowing, and leaf deformation on the leaves, in Samchcuk, South Korea. Cucumber and zucchini plants growing in the same field exhibited symptoms like those of bitter melon plants (Ali et al. 2012). To investigate the causative virus, leaf dip preparations from three symptomatic bitter melon leaf samples with symptoms were analyzed by transmission electron microscopy (TEM). Potyvirus-like particles (approximately 680-730 nm in length and 11-13 nm in diameter) were observed in all samples. To further identify the causal viral pathogens, leaf extracts from five symptomatic bitter melon plants were tested by DAS-ELISA using specific antibodies (Agdia, Elkhart, IN, USA) against cucumber mosaic virus, zucchini yellow mosaic virus (ZYMV), watermelon mosaic virus, and papaya ring spot virus. Positive controls from commercial kits and negative controls from healthy bitter melon plants were included in ELISA assay. The serological assay revealed that all five symptomatic samples positively reacted with the antiserum against ZYMV, but not for other viruses. Total RNA extracted from the five ELISA-positive samples and two healthy bitter melon plants (as negative controls), using Clear-S Total RNA extraction kit (InVirusTech Co., Gwangju, Korea), was tested by RT-PCR with ZYMV-specific primers as previously described (Cho et al. 2011). All amplicons of the expected size (~822 bp) were individually cloned into the pGEM-T Easy Vector (Promega, Madison, WI), and sequenced in both orientations. Thereafter, all the sequenced clones shared 100% nucleotide identity. The sequence of ZYMV-MC1 isolated from bitter melon was deposited in the GenBank (accession no. LC652434). Pairwise comparison of the nucleotide sequence with that of ZYMV isolates in the GenBank revealed 99% sequence identity with ZYMV-chk (MG020559) from Korea, 98% with ZYMV-14-HY-SCS (KU743321) from China, 97% with ZYMV-Y21 (MW345249) from Turkey, 96% with ZYMV-AUIKTPK (KR261951) from Pakstan. Leaf saps from the ZYMV-positive bitter melon samples, prepared in 10 mM phosphate buffer (pH 7.0), were mechanically inoculated in five young, healthy bitter melon plants to fulfil Koch's postulates. ZYMV-MC1 isolate caused mosaic and leaf deformation on bitter melon plants 10 days post-inoculation. The presence of ZYMV in the symptomatic leaves was confirmed by RT-PCR using the mentioned above primers mentioned above followed by nucleotide sequencing of the amplicons. Several cotton aphids (Aphis gossypii) were observed in the bitter melon field, which indicated that they might transmit the virus from ZYMV-infected cucumber or zucchini plants. ZYMV is one of the economically important viruses of cucurbits worldwide and has been recently reported from various crops as natural hosts, including Chayote (Yoon et al. 2018) and balloon flowers (Kim et al. 2021). To the best of our knowledge, this is the first report of ZYMV naturally infecting bitter melon in South Korea. Further large -scale surveys are required to determine its incidence, yield losses, and management in bitter melon in Korea.

Metagenomic Analysis of RNA Viruses in Watermelon

Watermelon is one of the most consumed cucurbits worldwide. Its production, nevertheless, is threatened by different pathogens that compromise the development of plants and, consequently, fruits. Here, plants showing typical virus-like symptoms were collected in the Tocantins State, Brazil. Aiming for the identification of viruses, viral RNA was sequenced by Illumina. Four virus genomes were sequenced and assembled, corresponding to isolates of Papaya ringspot virus (PRSV) and Zucchini Yellow Mosaic Virus (ZYMV) from the family Potyviridae, Groundnut ringspot virus (GRSV) from the family Bunyaviridae, and Citrullus lanatus partitivirus (CiLPV) from family Partitiviridae. Although these viruses have been previously reported infecting watermelon, we have sequenced the first complete genome of GRSV and the first complete genome of a ZYMV isolate from Brazil. Symptomatic watermelon leaves from the field were also used as inoculation for virus mechanical transmission to indicative plants. Despite co-infecting watermelon plants in the field, only the potyviruses were mechanically transmitted to indicative plants, in which ZYMV presented the broadest host range.

Characterization of a variant isolate of Zucchini yellow mosaic virus infecting green kabocha (Cucurbita maxima L.) in Bogor, Indonesia

Zucchini yellow mosaic virus (ZYMV) has been reported in Indonesia over the past decade. However, the biological, morphological, and molecular characterizations of Indonesian isolates of this virus have not yet been determined. In this study, we report a ZYMV isolate infecting green kabocha (Cucurbita maxima L.; GK) and exhibiting a typical chlorotic mosaic with vein banding symptoms. A bioassay performed on indicator plants demonstrated that the host range of the ZYMV-GK isolate was restricted to Cucurbitaceae, Amaranthaceae, and one Solanaceae family member, Nicotiana benthamiana. Interestingly, Luffa acutangula, a species in the Cucurbitaceae family, could not be infected with ZYMV-GK. Electron microscopy revealed the presence of filamentous virus-like particles, approximately 900 nm in length, characteristic to potyviruses. Sequence analysis of the coat protein gene confirmed that ZYMV-GK was a variant of ZYMV sharing 94.5% (96.7%) maximum nucleotide (amino acid) sequence identity with the GenBank sequence of a Vietnamese isolate (Acc.no. DQ925447.1).

Molecular characterization and identification of economically important Potyviruses in Cucurbitaceae family from Gujranwala division of Punjab, Pakistan

Cucurbits belongs to Cucurbitaceae family and they are main source of energy, vitamins and minerals. The plant viruses in general and potyviruses in particular are considered to hamper the successful production of cucurbits in Punjab province of Pakistan. The present study was undertaken to determine the current status of major potyviruses infecting cucurbits in Gujranwala division of Punjab. Overall, 528 samples of cucurbit species were collected from 46 fields of six districts (Narowal, Sialkot, Gujranwala, Gujrat, Mandi Baha Uddin and Hafizabad) in Gujranwala division. All disease samples were screened for the presence of potyvirus infection by indirect plate-trapped antigen (PTA)-ELISA using “Poty-group test” kit (Bioreba AG, Switzerland). These samples were further tested for Papaya ring spot virus (PRSV), Zucchini yellow mosaic virus (ZYMV) and Watermelon mosaic virus (WMV) (Bioreba AG) using virus specific DAS-ELISA. Zucchini yellow mosaic virus (ZYMV) was also further confirmed by reverse transcriptase polymerase chain reaction (RT-PCR). ZYMV was found as the most predominant virus of cucurbits in Gujranwala division with an average incidence of 20.8%, followed by PRSV (7.2%) and WMV (1.7%). Maximum mixed double infection was observed in combination of ZYMV+PRSV (1.3%) followed by ZYMV+WMV (0.4%) and WMV+PRSV (0.8%). Overall highest disease incidence of potyviruses was in Gujranwala (40.86%) followed by Narowal (34.65%), Gujrat (28.6%), Mandi Baha Uddin (26.56%), Hafizabad (25%) and Sialkot (23.21%). Likewise, the maximum ZYMV incidence was recorded in Angel Gourd whereas no viral infection was observed in snap melon and ash gourd in Gujranwala division. All cucurbits vegetables were found to be highly prone to ZYMV followed by PRSV and WMV. The sequence of CI region of ZYMV AABRM-CI ridge gourd isolate was deposited in GenBank with an accession no. MN897101, which showed nucleotide identities from 91.501-98.401% with other isolates of ZYMV available at database. Highest nucleotide identity 98.401% was found with the sequence of ZYMV South Korean isolate BR1 (MH042024) followed by 98.301% with ZYMV isolate Y23 from Turkey (KP828425). The results of the current study would be useful in devising management strategies to mitigate potyvirus losses in cucurbits from Pakistan.

Molecular characterisation of Zucchini yellow mosaic virus infecting Cucurbita pepo in Egypt

The complete nucleotide sequence of Zucchini yellow mosaic virus isolate from Egypt (ZYMV-Egz_MT383108) was determined. The sequence comparisons suggested that the isolate belongs to Group A. The sequence analysis of the Egyptian isolate showed the highest similarity (~96–97%) with the isolates leaf1 (KJ923767.1) and PA_2006 (JQ716413.1) from the USA and the lowest similarity (84%) with an isolate (AF014811.2) from Singapore. The phylogenetic analysis revealed that ZYMV-Egz occupied a distinct clade together with the USA isolates in Group A, known to be the most widespread throughout the world. This is a first record of the complete nucleotide sequence of an Egyptian isolate of ZYMV.

Analysis of the molecular and biological variability of Zucchini yellow mosaic virus isolates from Iran and Iraq.

During the growing season of 2018, several field-grown cucurbit plants in different parts of Iraq and Iran were surveyed for the presence of zucchini yellow mosaic virus (ZYMV), using two degenerate primer pairs (CIF/Rev and NIb2F/3R) targeting the two separated partial regions of the potyvirus genome (CI and NIb respectively). 7 out of 20 samples were confirmed to be infected with ZYMV. Phylogenetic analyses based on the CI gene grouped all Iranian and two Iraqi (ZYMV1 and ZYMV2) isolates together with isolates from the Middle East in the subgroup (AI), whereas the other Iraqi (ZYMV3 and ZYMV4) isolates were clustered in the subgroup (DI), which was only consisted of American isolates. The highest and lowest identity between the studied isolates and the GenBank isolates showed that the two genes (CI, NIb) of each isolate particularly the Iraqi isolates were more similar to a specific and geographically scattered mosaic of worldwide isolates, suggestive of mixed infection might have occurred between different worldwide isolates in Iraq. Furthermore, the first complete nucleotide sequence of an Iraqi ZYMV (ZYMV-Iq) isolate was done, using the Illumina sequencing technique. The complete nucleotide sequence of ZYMV-Iq isolate was 9650 nt, excluding the 3'poly (A) tail. ZYMV-Iq isolate shared the highest nt identity of 98.8% with an American (KC665630) isolate. Phylogenetic analysis based on the full genome sequence placed ZYMV-Iq in subgroup A of group I alongside 18 isolates from the US and two isolates from Australia. In addition, recombination analysis detected lone significant recombination between ZYMV-Iq and South Korean (AY279000) isolate. Moreover, the results showed that symptom intensity was varied across experimental host plants.

Genome characterization of zucchini yellow mosaic virus infecting cucurbits reveals the presence of a new genotype in Trinidad and Tobago in the Caribbean region.

Zucchini yellow mosaic virus (ZYMV) is a member of the genus Potyvirus that is becoming a serious pathogen of pumpkin and other cucurbits in Trinidad and Tobago and the entire Caribbean region. In this study, four ZYMV isolates infecting pumpkin in Trinidad and Tobago were characterized by complete genome sequencing. Phylogenetic analysis showed 5.9-6.0% nt and 7.7-7.9% aa sequence divergence in comparison to the most closely related isolates NAT and AG from Israel and SE04T from Slovakia. Based on the variations in the complete genome sequence as well as individual gene sequences, a new genotype, designated ZYMV-Trini, is proposed for these isolates. Among the gene sequences of ZYMV-Trini isolates, the greatest variation was observed in the HC-Pro gene, with 20.8% aa sequence divergence from their closest relatives, whereas the least variation was observed in the NIb, P3, and CP genes, with 1.8-2.2% aa sequence divergence. This study also showed that transmission of ZYMV can occur through seeds, but this was less common than transmission via the aphid Aphis gossypii. The progression of ZYMV in pumpkin seedlings was quantified by RT-qPCR, which showed a rapid surge in viral load after 37 days. From recombination analysis, it could be concluded that the isolates SE04T from Slovakia, NAT from Israel, and AG from Israel have made major contributions to the genome architecture of ZYMV-Trini isolates.

Detection and Molecular Characterization of Two Potyvirus Species on Cucurbits from Northwestern of Iran

Cucurbit crops belonging to the family Cucurbitaceae are one the most important horticultural crops worldwide and cultivated widely in Iran. To aim detection and phylogenetic analysis of potyvirus members, during 2015-2016, 215 leaf samples from cucumber, melon, watermelon, and squash symptomatic with deforming and reduction in leaf size, blistering, mild and severe mosaic, fruit deformation, and stunting were collected from 10 major cucurbits-growing locations in West Azerbaijan province. Following mechanical inoculation of Cucurbita pepo as an indicator plant with symptomatic cucurbit crop extracts, a variety of symptoms developed on the plants. Then, total RNA extracted from 70 symptomatic leaf samples, and partial RNA-dependent RNA polymerase (NIb) (350 bp) was amplified using universal primer pairs (NIb2F/NIb3R) by reverse transcription-polymerase chain reaction (RT-PCR). The infection by potyviruses in 38.75% of the samples was confirmed based on the result. The five PCR products belonging to different hosts at the expected size (350bp) were sequenced. One sample (Ir-Na: MH491979) was determined to be infected by the Watermelon mosaic virus (WMV) whereas four samples (Ir-Ma:MH491979, Ir-Ng:MH491980, Ir-Pi:MH491981, and Ir-Ur:MH491982) infected by Zucchini yellow mosaic virus (ZYMV). In the phylogenetic analysis based on Maximum-likelihood, three ZYMV isolates (Ir-Ng, Ir-Pi, and Ir-Ur) were placed in subgroup I whereas one isolate (Ir-Ma) was placed in subgroup II belonging to group A. Also, WMV isolate (Ir- Na) was placed in CL phylogroup.

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.

Genomic sequence variability of an Italian Zucchini yellow mosaic virus isolate

Zucchini yellow mosaic virus (ZYMV) was first reported in Italy, but no Italian isolates have been sequenced so far. A ZYMV isolate, designated Z104, was isolated from a zucchini plant grown in the open field in Piedmont, Italy, and showing severe disease symptoms. We report the full-length genome sequence of Z104 as determined by Sanger sequencing and small (s)RNA deep sequencing. The latter technique was useful to confirm the isolate sequence, that was deposited in the NCBI database with the accession number MK956829 and to investigate the sequence variability of Z104 isolate. The genome of 9611 nucleotides (nt) consisted of an open reading frame of 9243 nt encoding a polyprotein of 3080 amino acids (349.88 kDa), flanked by the 5′- and 3′-untranslated regions, and an overlapping ORF of 74 amino acids, the P3N-PIPO. As in previously sequenced ZYMV isolates, Z104 polyprotein consists of 10 putative functional proteins. Several domains in the HC-Pro and P3 proteins related to the transmissibility by aphids and virus aggressiveness are conserved in Z104. Symptoms induced both in the field and laboratory by Z104 together with its molecular features indicate that it is an aggressive strain. Deep sequencing of sRNAs revealed a particularly high variability in the genome sequence at eight nucleotide positions, three of which resulted in missense mutations in the P3, 6K1, and NIb proteins. This may be indicative of the natural ZYMV genome variability within the host. The phylogenetic analysis of the whole genome or the sole coat protein of several ZYMV isolates did not provide evidence for a close relationship of Z104 with other isolates from European countries. To the best of our knowledge, this is the first-reported complete genome of a ZYMV isolate from Italy.

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.

Population Genetic Analysis of Zucchini yellow mosaic virus based on the CI Gene Sequence

Zucchini yellow mosaic virus (ZYMV) is one of the most economically important viruses infecting cucurbits worldwide. Population genetic analysis of ZYMV was conducted based on the virus cylindrical inclusion (CI) gene sequences of 10 isolates identified in this study and 94 other isolates from different countries in six continents: Asia, Europe, Oceania, Africa, North and South America. The overall mean value of nucleotide sequence diversity among all isolates was 0.074±0.006. Phylogenetic analysis showed that ZYMV isolates fell into three main phylogroups with significant FST values (>0.55) and almost tended to cluster according to their geographical position. Group I was predominant and contained isolates originated from different parts of the world. Iranian isolates clustered into group I, sharing 87.7-99.7% and 92.5–100% nucleotide and amino acid identity, with other isolates of this group. Group II was a new group that included only Singapore isolates. Group III including East Timor, Reunion Island and Australia-Kununurra isolates which were genetically differentiated from other populations. ZYMV populations from different geographic origins were composed of multiple lineages. With exception of the Oceanian population which was strongly differentiated from the American population, most other geographical populations showed low to moderate genetic differentiation. There was moderate to high level of gene flow despite large separating geographic distances. Analysis of the synonymous-to-nonsynonymous ratio showed strong purifying selection in the CI gene. The analyses indicated that in addition to selection, random processes such as genetic drift and founder effects are important determinants for the genetic structure of populations of ZYMV.

Complete Genome Sequence of a Zucchini Yellow Mosaic Virus Isolated from Pumpkin in Oklahoma.

Zucchini yellow mosaic virus (ZYMV) (genus Potyvirus, family Potyviridae) was first isolated in Europe during the 1970s and in the United States in 1981. Here, we report the complete genome sequence of ZYMV isolate BL-67, isolated from pumpkin in Oklahoma during the 2016 growing season.

Biological and molecular characterization of Zucchini yellow mosaic virus isolates infecting melon in Xinjiang, China

Zucchini yellow mosaic virus (ZYMV) causes one of the most destructive diseases of cucurbits worldwide. Although the virus has been present in China for more than 25 years, there is little information about biological and molecular traits of ZYMV isolates from China. This study aimed to characterize 26 ZYMV isolates from Xinjiang, China based on pathotypes, molecular variability and host range. Phylogenetic analysis of the complete sequences of the coat protein gene revealed three distinct groups (A, B and C), with four subgroups in A (I–IV). All isolates from Xinjiang were placed in group C and subgroups A–I and A–II. To test for differences in host range among different phylogenetic groups from Xinjiang, 13 isolates were mechanically inoculated onto 14 plant species in five families and their pathotypes were also identified based on the reaction of a resistant melon accession PI414723. Overall, the results showed that there were no correlations of host responses to inoculation with ZYMV isolates from different phylogenetic groups. However, on Cucurbita pepo, differences in host responses to inoculation with the ZYMV isolates from different phylogenetic groups were observed. Although the host range of the 13 isolates tested was similar, their biological properties on different hosts were slightly different from the ZYMV isolates characterized in other countries. The results of the pathotype test showed that the 13 ZYMV isolates were classified as pathotype 0. The information obtained is important in breeding for resistant varieties.

Phylogenetic analysis of see-transmitted isolate of Zucchini yellow mosaic virus

Zucchini yellow mosaic virus (ZYMV) remains one of the most widespread and destructive viruses affecting plants from Cucurbitaceae family in Ukraine as well as in other countries. ZYMV during the early stages of plant development can cause significant losses in yield. In current project the possibility of seed transmission of Ukrainian ZYMV isolates was tested on Cucurbita pepo plants in insect-free greenhouse. The rate was assessed by ELISA and RT-PCR. Only one isolate ZYMV-14P showed seedborne transmission with transmission rate 2,6%. This is the first detected seed-transmitted isolate in Ukraine. Phylogenetic analysis defined ZYMV-14P isolate as member of group A. This isolate was clustered with other known Ukrainian isolates and isolates from Hungary, Czech Republic, Austria and France within subgroup AI.

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.

FIRST REPORT OF ZUCCHINI YELLOW MOSAIC VIRUS ON MUSKMELON IN INDIA

Zucchini yellow mosaic virus (ZYMV, genus Potyvirus in the family Potyviridae) is the causal agent of diseases in a wide range of cucurbitaceae host species, causing important economic losses. During a 2014 survey of the main muskmelon (Cucumis melo) growing areas of Rajasthan in India, plants showing virus-like symptoms such as leaf curling, yellow vein mosaic, decreased leaf size and stunting were observed. Leaves from symptomatic plants were collected, total RNA was extracted from infected leaves using the TRIZOL (Sambrook and Russell, 2001) method and subjected to RT-PCR using potyvirus degenerate primers Pot1 and Pot2 (Colinet et al., 1997). A ca. 1.5 kb amplicon was partially sequenced and deposited in GenBank (Accession no. KJ425470) as Zucchini yellow mosaic virus isolate Rajasthan. BLASTn revealed 100% sequence identity with ZYMV-SG from China (AJ316228), 96% with ZYMV-NAT from Israel (EF062282) and 95% with ZYMV-fars from Iran (JN183062). In a phylogenetic analysis ZYMV-Rajasthan clustered with Asian ZYMV isolates. ZYMV was previously reported from cucurbitaceae species but, to our knowledge, this is the first report of ZYMV on muskmelon in India.

Incidence and phylogeny of viruses infecting cucurbit crops in KwaZulu-Natal, Republic of South Africa

Virus infections on cucurbits often result in substantial losses. Surveys were conducted throughout the province of KwaZulu-Natal (KZN) in the Republic of South Africa (RSA) during the 2011–2013 growing seasons to identify cucurbit-infecting viruses. Viruses were detected on sampled leaves displaying virus-like symptoms using double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and reverse transcription polymerase chain reaction (RT-PCR). The phylogenetic relationships of all detected viruses were also studied. Cucumber mosaic virus (CMV), Beet pseudo-yellows virus (BPYV), Zucchini yellow mosaic virus (ZYMV), Moroccan watermelon mosaic virus (MWMV) and a Polerovirus were detected at an incidence of 3.48%, 10%, 13.04%, 48.70% and 41.67% respectively. Phylogenetic analyses identified CMV isolates as members of the Subgroup IA of the CMV lineage and ZYMV isolates as members of the subgroups AI and AII of the of ZYMV lineage. MWMV isolates formed a distinct clade within the Southern African group of the MWMV lineage. Polerovirus isolates were identified as Pepo aphid-borne yellows virus (PABYV) based on the sequence similarity and phylogenetic analyses. The information generated from this study will contribute towards the development of effective management strategies against viruses infecting cucurbits in KZN.