Zucchini Yellow Mosaic Virus Strains Research Articles

Response of Some Watermelon Accessions to a Puerto Rico Strain of Zucchini yellow mosaic virus

One of the most important members of the Potyviridae is Zucchini yellow mosaic virus (ZYMV). It affects watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] as well as other cucurbits in most parts of the world. Although several genotypes have been reported as having resistance to ZYMV, differential responses to ZYMV strains are known to occur. Using a Puerto Rico strain of ZYMV (ZYMV-PR, GenBank accession number MN422959), we tested the response of 11 genotypes [PIs from the U.S. Department of Agriculture (USDA) National Genetic Resources Program] previously reported as having resistance to this virus. In two greenhouse trials, the first three leaves of seedlings of each genotype were mechanically inoculated with ZYMV-PR. An enzyme-linked immunosorbent assay (ELISA) was done on each seedling’s fourth leaf and symptom severity was rated on the first, third, fifth, and seventh leaves. There were significant genotype × trial interactions for most variables, but some genotypes performed consistently in both trials. All seedlings of PI 537277 tested negative for ELISA (absorbance < 0.200) across both trials. PI 537277, PI 595200, PI 595201, and PI 595203 were generally among the accessions with the lowest symptom severity scores. Overall, symptom severity correlated poorly with ELISA readings. But all plants of PI 537277, and most plants of PI 595201 and PI 595203, had low ELISA readings and low severity scores. Despite having low severity scores, PI 595200 was among the genotypes with the highest ELISA readings in trial 2. For the plant breeder, the most useful genotypes are those that exhibit reduced severity as well as low ELISA. PI 537277, PI 595201, and PI 595203 met those criteria in this study. Of these three accessions, PI 595203 would be the most useful in a breeding program because it has shown resistance to the Puerto Rico, Florida, and China strains of ZYMV.

Molecular identification and phylogeny of cucumber mosaic virus and zucchini yellow mosaic virus co-infecting Luffa cylindrica L. in Shanxi, China

To identify the viruses that induced Luffa cylindrica L. mosaic disease, the viral genomic double-strand RNA (dsRNA) was extracted, followed by sequence-independent amplification (SIA) and sequencing. Results showed that Luffa cylindrica L. was co-infected by cucumber mosaic virus (CMV) and zucchini yellow mosaic virus (ZYMV). To further characterize the Shanxi isolates of cucumber mosaic virus (CMV-SXSG) and zucchini yellow mosaic virus (ZYMV-SXSG), the MP gene sequence of CMV-SXSG and the complete genomic sequence of ZYMV-SXSG were cloned and analyzed. The genomic RNA of ZYMV-SXSG is 9474 nucleotides in length and contains one putative ORF which encodes a polyprotein of 3080 amino acids. Sequence alignments showed that CMV-SXSG shared MP nucleotide sequence identities with other CMV isolates of 78.15% to 99.4%. The nucleotide sequence similarity for the CDS region between ZYMV-SXSG and representative ZYMV strains ranged from 81.71% to 98.40%. Phylogenetic analysis suggested that CMV-SXSG and CMV-QZ shared the same origin, and that ZYMV-SXSG showed the highest sequence identity to isolate KR-PA and formed an independent branch, indicating that they have the most closely evolutionary relationship. Recombination analysis revealed that ZYMV-SXSG was a putative recombinant, and that the potential major and minor parents were the ZZ (China isolate) and KR-PA (Korean isolate), respectively. These results will provide valuable hints for more accurate analysis of CMV or ZYMV genetic diversity, and also provide an effective theoretical basis for designing better virus control strategies.

Zucchini yellow mosaic virus: insect transmission and pathogenicity —the tails of two proteins

SUMMARY Taxonomy: Zucchini yellow mosaic virus (ZYMV) is a member of genus Potyvirus, family Potyviridae. ZYMV is a positive-strand RNA virus. Physical properties: Virions are flexuous filaments of 680-730 nm in length and 11-13 nm in diameter, composed of about 2000 subunits of a single 31-kDa protein (calculated). The genome RNA size is 9.6 kb covalently linked to a viral-encoded protein (the VPg) at the 5' end, and with a 3' poly A tail. The 5' end of the sequence is AU-rich (69%). Viral proteins: The genome is expressed as a polyprotein cleaved by three viral proteases and processed into ten putative mature proteins. The structural coat protein is processed from the carboxyl terminus of the polyprotein and is highly immunogenic. Host and symptoms: Natural and experimental infection has been reported mainly in the Cucurbitaceae. Experimental local lesion hosts include Chenopodium amaranticolour, C. quinoa and Gomphrena globosa. Some ZYMV strains cause symptomless infection as in Ranunculus sardous, Nicotiana benthamiana and Sesamum indicum. ZYMV causes stunting and major foliar deformation with dark green blisters and mosaics in cucurbit hosts, eventually developing a filamentous leaf phenotype. In general, symptoms are severe on cucurbit hosts and cause dramatic reductions in yields due to severe fruit deformation. The virus is present in all the plant tissues at relatively high concentrations (c. 0.1 mg/mL of purified virus per 1 g fresh leaf tissue). The most suitable species for maintenance and purification is Cucurbita pepo. ZYMV is efficiently transmitted by aphids in a non-persistent manner. The coat protein (CP) and the helper component-protease (HC-Pro) are required for aphid transmission, through the CP DAG motif and the HC-Pro KLSC and PTK motifs. Mechanical transmission is efficient both in the laboratory and naturally. Economic importance: ZYMV disease is a major constraint in the production of cucurbits world-wide. The virus can cause massive damage (to total loss) to cucurbit crops, and prevents the growth of some cucurbit crops in certain areas. Control of ZYMV requires the integration of conventional resistance and transgenic breeding along with cross-protection technologies.

Localization of Zucchini yellow mosaic virus to the veinal regions and role of viral coat protein in veinal chlorosis conditioned by the zym potyvirus resistance locus in cucumber

The zym locus in cucumber (Cucumis sativus L.) is marked by multiple alleles conferring resistance to the potyvirus, Zucchini yellow mosaic virus (ZYMV). Cotyledon inoculation of greenhouse grown plants expressing the zymDina allele results in a distinct pattern of veinal chlorosis limited to a single systemic leaf; leaf-inoculated plants remain free of symptoms. Inoculation of cotyledons of plants of different growth stages indicated that the virus moved to the leaf that was newly emerging at the time of cotyledon infection where it then remained localized to the veinal regions for up to 30 days post-inoculation (d.p.i). Cotyledon removal experiments indicated that the inability of ZYMV to spread within the uninoculated leaf, or to infect inoculated leaves, was not due to the inability to replicate in leaves. Chimeric viruses generated from a strain of ZYMV that did not induce the veinal chlorosis response, indicated that the coat protein amino terminus, which has been shown to be involved in long distance movement, affected occurrence of veinal chlorosis. In the growth chamber, inoculation of the first leaf, but not subsequent leaves, gave a high percentage of plants expressing veinal chlorosis. Together, these observations suggest that resistance conferred by zymDina is developmentally regulated and occurs at the level of systemic movement.

Oligogenic inheritance for resistance to Zucchini yellow mosaic virus in Cucurbita pepo

Summary‘True French’ is an open‐pollinated cultivar of the Zucchini (Courgette) Group of Cucurbita pepo and is susceptible to Zucchini yellow mosaic virus (ZYMV). Using C. moschata‘Menina’ as the source of ZYMV resistance and following six generations of backcrossing, a true‐breeding line nearly isogenic to ‘True French’, designated 381e, was recovered that carried ZYMV resistance, albeit not at as high a level as in ‘Menina’. ‘True French’ and accession 381e were crossed, and their reciprocal F1, F2, and backcross progenies were grown in a chamber and inoculated with a highly virulent, non‐aphid‐transmissible strain of ZYMV. Nearly all F1 plants and all plants of the backcross to 381e were classified as resistant. Segregation to resistant and susceptible individuals occurred in the backcross to the susceptible parent, in accordance with a 3:5 three‐gene ratio of resistant: susceptible. The F2 segregated in accordance with a ratio of 45 resistant : 19 susceptible, which would be obtained if there was one major gene for resistance, Zym‐1 (Zym), and two other genes, herein designated Zym‐2 and Zym‐3, both of which for complementary to Zym‐1. The presence of Zym‐1 and either Zym‐2 or Zym‐3 is necessary for resistance to be expressed in young plants, but the presence of all three might be necessary for resistance to continue to be expressed during subsequent development of the plants. Evidently, Zym‐2 and Zym‐3 are ubiquitous in C. moschata but their susceptible alleles are much more common in C. pepo. As the level of resistance of 381e to ZYMV is not as high as that of C. moschata‘Menina’, additional, as yet unidentified, genes must be involved in conferring high resistance to this virus.

Identification of Zucchini yellow mosaic potyvirus by RT-PCR and analysis of sequence variability.

A reverse transcription-polymerase chain reaction (RT-PCR) method was used to identify Zucchini yellow mosaic virus (ZYMV) in leaves of infected cucurbits. Oligonucleotide primers which annealed to regions in the nuclear inclusion body (NIb) and the coat protein (CP) genes, generated a 300-bp product from ZYMV and also from the closely related watermelon mosaic virus type 2 (WMV-2). However, no product was obtained from papaya ringspot potyvirus which also infects cucurbits. ZYMV and WMV-2 were differentiated using a third primer which was complementary to a sequence in the 3'-untranslated region; a 1186-bp amplified product was obtained for ZYMV only. Nucleotide sequence analysis of the 300-bp fragments of Australian ZYMV and WMV-2 strains revealed 93.7-100% sequence identity between ZYMV strains. Multiple sequence alignments indicated that the nucleotide sequence which codes for the N-terminus of the CP was 74-100% identical for different isolates of ZYMV. The Australian isolate of WMV-2 was 43-46% identical to all isolates of ZYMV and was 84.6% identical to a Florida isolate of WMV-2.

Comparative Biological and Serological Properties of Four Strains of Zucchini Yellow Mosaic Virus

Four strains of zucchini yellow mosaic virus (ZYMV) from Connecticut (CT), Florida (FL), France (WK), and Taiwan (TW) were partially characterized and compared. Host ranges of the four strains were similar but they differed in the ability to infect specific hosts. All ZYMV strains were indistinguishable in SDS-immunodiffusion tests. After cross-absorption with antigens of ZYMV-CT and -FL, antiserum to ZYMV-TW reacted with ZYMV-TW but not with ZYMV-CT, -FL, or -WK in enzyme-linked immunosorbent assays(.)