Detection of Plant Viruses in Some Ornamental Plants That Act as Alternate Hosts

A study was conducted at the Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Salna, Gazipur to detect virus infecting ornamental plants. Enzyme-linked Immunosorbant Assay (ELISA) and symptomalogy were used for detection. Five viruses namely TPVV (Tomato Purple Vein Virus), CMV-Y (Cucumber Mosaic Virus-Y), OYVCMV (Okra Yellow Vein clearing Mosaic Virus), MYMV (Mung bean Yellow Mosaic Virus), TYLCV (Tomato Yellow Leaf Curl Virus) were detected on Tagetes erecta (Marigold), Salvia splendens (Salvia), Dahlia hybrida (Dahlia), Helichrysum bracteatum (Straw flower), Impatiens balsamina (Garden balsam). CMV-Y caused mosaic of Dahlia and Leaf Curl of Marigold. MYMV caused Yellow Mosaic of Dahlia hybrid, while TYLCV caused mosaic of Helichrysum bracteatum. OYVCMV produced leaf chlorosis on Salvia splendens, and chlorotic spots on Impatiens balsamina. TPVV caused purple leaf on Tagetes erecta DOI: http://dx.doi.org/10.3329/agric.v10i2.13141 The Agriculturists 2012; 10(2) 46-54

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Towards plant resistance to viruses using protein-only RNase P

Nature Communications ◽

10.1038/s41467-021-21338-6 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Anthony Gobert ◽

Yifat Quan ◽

Mathilde Arrivé ◽

Florent Waltz ◽

Nathalie Da Silva ◽

...

Keyword(s):

Mosaic Virus ◽

Virus Replication ◽

Yield Loss ◽

Rnase P ◽

Plant Viruses ◽

Yellow Mosaic Virus ◽

Resistance To Viruses ◽

Target Plant

AbstractPlant viruses cause massive crop yield loss worldwide. Most plant viruses are RNA viruses, many of which contain a functional tRNA-like structure. RNase P has the enzymatic activity to catalyze the 5′ maturation of precursor tRNAs. It is also able to cleave tRNA-like structures. However, RNase P enzymes only accumulate in the nucleus, mitochondria, and chloroplasts rather than cytosol where virus replication takes place. Here, we report a biotechnology strategy based on the re-localization of plant protein-only RNase P to the cytosol (CytoRP) to target plant viruses tRNA-like structures and thus hamper virus replication. We demonstrate the cytosol localization of protein-only RNase P in Arabidopsis protoplasts. In addition, we provide in vitro evidences for CytoRP to cleave turnip yellow mosaic virus and oilseed rape mosaic virus. However, we observe varied in vivo results. The possible reasons have been discussed. Overall, the results provided here show the potential of using CytoRP for combating some plant viral diseases.

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Genome-Wide Identification and Expression Analysis of the Histone Deacetylase Gene Family in Wheat (Triticum aestivum L.)

Plants ◽

10.3390/plants10010019 ◽

2020 ◽

Vol 10 (1) ◽

pp. 19

Author(s):

Peng Jin ◽

Shiqi Gao ◽

Long He ◽

Miaoze Xu ◽

Tianye Zhang ◽

...

Keyword(s):

Abiotic Stress ◽

Gene Family ◽

Mosaic Virus ◽

Stress Responses ◽

Viral Infections ◽

Phylogenetic Analyses ◽

Plant Viruses ◽

Gene Family Evolution ◽

Yellow Mosaic Virus ◽

Wheat Yellow Mosaic Virus

Histone acetylation is a dynamic modification process co-regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs). Although HDACs play vital roles in abiotic or biotic stress responses, their members in Triticumaestivum and their response to plant viruses remain unknown. Here, we identified and characterized 49 T. aestivumHDACs (TaHDACs) at the whole-genome level. Based on phylogenetic analyses, TaHDACs could be divided into 5 clades, and their protein spatial structure was integral and conserved. Chromosomal location and synteny analyses showed that TaHDACs were widely distributed on wheat chromosomes, and gene duplication has accelerated the TaHDAC gene family evolution. The cis-acting element analysis indicated that TaHDACs were involved in hormone response, light response, abiotic stress, growth, and development. Heatmaps analysis of RNA-sequencing data showed that TaHDAC genes were involved in biotic or abiotic stress response. Selected TaHDACs were differentially expressed in diverse tissues or under varying temperature conditions. All selected TaHDACs were significantly upregulated following infection with the barley stripe mosaic virus (BSMV), Chinese wheat mosaic virus (CWMV), and wheat yellow mosaic virus (WYMV), suggesting their involvement in response to viral infections. Furthermore, TaSRT1-silenced contributed to increasing wheat resistance against CWMV infection. In summary, these findings could help deepen the understanding of the structure and characteristics of the HDAC gene family in wheat and lay the foundation for exploring the function of TaHDACs in plants resistant to viral infections.

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First Report of Pea enation mosaic virus Infecting Pea and Broad Bean in Spain

Plant Disease ◽

10.1094/pdis-92-10-1469c ◽

2008 ◽

Vol 92 (10) ◽

pp. 1469-1469 ◽

Cited By ~ 4

Author(s):

T. Tornos ◽

M. C. Cebrián ◽

M. C. Córdoba-Sellés ◽

A. Alfaro-Fernández ◽

J. A. Herrera-Vásquez ◽

...

Keyword(s):

Mosaic Virus ◽

Genomic Sequence ◽

Broad Bean ◽

Direct Sequencing ◽

Plant Viruses ◽

Positive Sample ◽

Yellow Mosaic Virus ◽

First Report ◽

Wilt Virus ◽

Pea Enation Mosaic Virus

During the spring of 2007, pea plants (Pisum sativum L.) (cvs. Utrillo and Floreta) showing virus-like symptoms were observed in several commercial fields in the southern and eastern regions of Catalonia, Spain. Incidence of symptomatic plants ranged from 5 to 15% and was distributed in both small and large patches. Infected plants exhibited yellow mosaic leaf symptoms that later became translucent. Leaves gradually curled and in some cases developed enations near the veins on the abaxial surface. Plants were “bushy” and had shortened internodes. Infection prior to pod formation resulted in pods that were distorted and stunted (1). The infected leaves and pods were tested by indirect-ELISA with a potyvirus-specific antibody (Agdia, Elkhart, IN) and double-antibody sandwich (DAS)-ELISA with antibodies specific to Pea enation mosaic virus (PEMV), Broad bean wilt virus 1 (BBWV-1), Beet western yellow virus (BWYV), Bean yellow mosaic virus (BYMV), Alfalfa mosaic virus (AMV), and Tomato spotted wilt virus (TSWV) (Loewe Biochemica GmbH, Sauerlach, Germany). PEMV was detected in all 24 symptomatic samples that were collected from 10 locations between March 2007 and March 2008. Thirteen of these samples also tested positive for BWYV, but no differences in symptom expression were observed in plants infected with both viruses or PEMV alone. PEMV was also identified in seven broad bean plants (Vicia faba L.) from three additional locations. These plants expressed interveinal yellow mosaic on leaves and deformed pods. The genomic sequence of PEMV-1 (GenBank Accession No. L04573) was used to design primers to amplify a 451-nt segment of the polymerase gene by reverse transcription (RT)-PCR; PEMV-D (5′-TGACCATGAGTCCACTGAGG-3′), PEMV-R (5′-AGTATCTTCCAACAACCACAT-3′). One ELISA-positive sample was analyzed and the expected size amplicon was generated. Direct sequencing (GenBank Accession No. EU652339) revealed that PEMV-1 and our pea isolate have nucleotide sequence identities of 95%. To our knowledge, this is the first report of PEMV in Spain, which might cause important economical losses since PEMV is an important viral disease of pea and other legumes worldwide. Reference: (1) J. S. Skaf and G. A. Zoeten. No. 372 (No. 257 revised) in: Description of Plant Viruses. AAB, Kew, Surrey, England, 2000.

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A Polish Isolate of Zucchini yellow mosaic virus from Zucchini is Distinct from Other European Isolates

Plant Disease ◽

10.1094/pdis-91-5-0639b ◽

2007 ◽

Vol 91 (5) ◽

pp. 639-639 ◽

Cited By ~ 2

Author(s):

H. Pospieszny ◽

B. Hasiów ◽

N. Borodynko

Keyword(s):

Amino Acid ◽

Mosaic Virus ◽

Citrullus Lanatus ◽

Zucchini Yellow Mosaic Virus ◽

Amino Acid Identity ◽

Plant Viruses ◽

Yellow Mosaic Virus ◽

Parameter Method ◽

Acid Identity ◽

Conserved Sequence

Zucchini yellow mosaic virus (ZYMV) is a member of the Potyvirus genus in the Potyviridae family, the largest group of plant viruses. Different isolates of this virus have been found in infected cucurbits throughout the world, including localities in Europe, America, Australia, and Asia. In August 2005, mosaic and yellowing of leaves, as well as yellow spots on green fruits, were observed on zucchini (Cucurbita pepo cv. giromontiina) growing in commercial fields in the Kujawsko-Pomorskie Region of Poland. Flexuous virus particles (~750 nm long), typical of potyviruses, were observed in leaf-dip preparations from symptomatic zucchini plants. The virus in the sap from symptomatic plants was mechanically transmitted and systemic infections were produced on Citrullus lanatus, Cucumis melo, Cucumis sativus, C. pepo cvs. giromontiina and patissoniana, C. maxima, and Nicotiana benthamiana. Severe symptoms such as severe malformation of leaves and stunting of plants were observed on zucchini plants (cv. giromontiina) infected mechanically with the virus and grown in the greenhouse. Double-antibody sandwich (DAS)-ELISA using an anti-ZYMV polyclonal antiserum (AS-0234; DSMZ, Braunschweig, Germany) identified the presence of ZYMV in mechanically infected C. pepo cv. giromontiina and N. benthamiana plants. Subsequently, a reverse transcription (RT)-PCR using a universal primer, Sprimer, designed from the consensus sequences that code for the conserved sequence GNNSGQP in the NIb region of Potyviridae family members and the M4 primer was performed (1). The 1740-bp PCR fragments were cloned into the pGEM-T vector (Promega, Madison, WI) and three randomly selected clones were sequenced on an ABI automatic sequencer. An 837-bp sequence representing the full length coat protein gene (GenBank Accession No. EF178505) was compared with homologous sequences from other ZYMV isolates using BioEdit and Mega 3.1 softwares. Genetic distances were calculated by Kimura's two-parameter method (2). Surprisingly, the Polish ZYMV isolate (ZYMV-Zug) was more closely related to ZYMV isolates from Asia than those from Europe. Pairwise comparisons of ZYMV-Zug with several other European ZYMV isolates (GenBank Accession Nos. DQ645729, AJ420020, AJ459956, AJ420014, AJ420019, DQ124239, and AJ420018) indicated an 81 to 82% nucleotide and 91 to 92% amino acid identity, while there was a 94% nucleotide and 99% amino acid identity with the Shanxi (GenBank Accession No. AY074808) and Shandong isolates (GenBank Accession No. AF513552) from China. References: (1) J. Chen et al. Arch. Virol. 146:757, 2001. (2) S. Kumar et al. Brie. Bioinform. 5:150, 2004.

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Assessment of Common Soybean-Infecting Viruses in Ohio, USA, Through Multi-site Sampling and High-Throughput Sequencing

Plant Health Progress ◽

10.1094/php-rs-16-0018 ◽

2016 ◽

Vol 17 (2) ◽

pp. 133-140 ◽

Cited By ~ 1

Author(s):

Junping Han ◽

Leslie L. Domier ◽

Bryan J. Cassone ◽

Anne Dorrance ◽

Feng Qu

Keyword(s):

Mosaic Virus ◽

High Throughput ◽

High Throughput Sequencing ◽

Virus Disease ◽

Soybean Mosaic Virus ◽

Alfalfa Mosaic Virus ◽

Plant Viruses ◽

Yellow Mosaic Virus ◽

Tobacco Streak Virus ◽

Streak Virus

Multi-site sampling was conducted during 2011 and 2012 to assess the scope of virus disease problems of soybean in Ohio, USA. A total of 259 samples were collected from 80 soybean fields distributed in 42 Ohio counties, accounting for more than 90% of major soybean-growing counties in Ohio. A high-throughput RNA-Seq approach was adopted to identify all viruses in the samples that share sufficient sequence similarities with known plant viruses. To minimize sequencing costs, total RNA extracted from up to 20 samples were first pooled to make up regional pools, resulting in eight regional pools per year in both 2011 and 2012. These regional pools were further pooled into two yearly master pools of RNA, and sequenced using the Illumina's HiSeq2000 platform. Bioinformatic analyses of sequence reads led to the identification of signature sequences of nine different viruses. The originating locations of these viruses were then mapped with PCR or RT-PCR. This study confirmed the widespread distribution of Bean pod mottle virus, Soybean vein necrosis virus, Tobacco ringspot virus, and Tobacco streak virus in Ohio. It additionally revealed occasional association of Alfalfa mosaic virus, Bean yellow mosaic virus, Clover yellow vein virus, Soybean mosaic virus, and Soybean Putnam virus with Ohio soybean. This is the first statewide survey of soybean viruses in Ohio, and provides the much-needed baseline information for management of virus diseases of soybean. Accepted for publication 20 May 2016. Published 10 June 2016.

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Serological Studies Using Polyclonal Antisera Prepared Against the Viral Coat Protein of Four Begomoviruses Expressed in Escherichia coli

Plant Disease ◽

10.1094/pdis.2002.86.10.1109 ◽

2002 ◽

Vol 86 (10) ◽

pp. 1109-1114 ◽

Cited By ~ 11

Author(s):

A. M. Abouzid ◽

J. Freitas-Astua ◽

D. E. Purcifull ◽

J. E. Polston ◽

K. A. Beckham ◽

...

Keyword(s):

Escherichia Coli ◽

Coat Protein ◽

Mosaic Virus ◽

Yellow Mosaic Virus ◽

Enzyme Linked Immunosorbent Assay ◽

Thin Sections ◽

Golden Yellow ◽

Polyclonal Antisera ◽

Leaf Curl Virus ◽

Leaf Curl

Polyclonal rabbit antisera were produced to the coat protein of Bean golden mosaic virus Brazil isolate (BGMV), Cabbage leaf curl virus (CabLCV), Tomato yellow leaf curl virus (TYLCV), and Tomato mottle virus (ToMoV), all expressed in Escherichia coli by the pETh expression vector. The expressed coat protein of each virus was purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for use as an immunogen. The antisera to BGMV, CabLCV, TYLCV, and ToMoV reacted in indirect (plate-trapping) enzyme-linked immunosorbent assay (ELISA) with extracts from begomovirus-infected tissue. The antisera to BGMV, CabLCV, TYLCV, and ToMoV also reacted specifically with the test begomovirus antigens in leaf imprint blots and Western blots. The CabLCV and TYLCV antisera were used to detect Bean golden yellow mosaic virus antigens by immunogold labeling of thin sections of infected bean tissues. In tissue blot immunoassays, the TYLCV antiserum reacted well with TYLCV antigens but not with ToMoV antigens, while CabLCV antiserum reacted well with ToMoV antigens and weakly with TYLCV antigens. The results indicate that polyclonal antisera prepared to expressed begomovirus coat proteins were useful for the detection of begomoviruses in an array of assays.

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Growth Responses and Accumulation Characteristics of Three Ornamental Plants to Sn Contamination in Soil

Agriculture ◽

10.3390/agriculture11030205 ◽

2021 ◽

Vol 11 (3) ◽

pp. 205

Author(s):

Yuxia Liu ◽

Weili Xu ◽

Yi Wang ◽

Weiduo Hao ◽

Qixing Zhou ◽

...

Keyword(s):

Contaminated Soil ◽

Bioconcentration Factor ◽

Wide Spectrum ◽

Ornamental Plants ◽

Tagetes Erecta ◽

Growth Responses ◽

Impatiens Balsamina ◽

Mirabilis Jalapa ◽

High Concentrations ◽

Tagetes Erecta L

Decorative ornamental plants have been applied as hyperaccumulators/phytoremediators to a wide spectrum of heavy metal contaminants. In this study, pot culture experiments were conducted to investigate the Sn tolerance and accumulation in Impatiens balsamina L., Mirabilis jalapa L. and Tagetes erecta L., in order to assess the possibility of these three ornamental plants to be used as phytoremediators of Sn-contaminated soil. Results show that all three plants exhibited strong tolerance to Sn contamination, and no significant visual toxicity was observed for all three plants grown under most of the Sn treatments. The amount of Sn accumulated in the three plants was positively correlated with the Sn concentration in the soil. The order of the Sn accumulative capacity was Impatiens balsamina > Mirabilis jalapa > Tagetes erecta. Impatiens balsamina and Tagetes erecta showed a low translocation ability (TF) (<1), and the roots accumulated the highest Sn concentration, but Impatiens balsamina showed a relatively high bioconcentration factor (BCF, Sn concentration in each part > 100 mg/kg after Sn treatment of 500 mg/kg). Meanwhile, the TF of Mirabilis jalapa was >1, and the fluorescence accumulated the most Sn. In combination with the adaptation to high concentrations of various heavy metals, these three ornamental plants are potential candidates for Sn mining tailings or contaminated soil.

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New Record of Catharanthus yellow mosaic virus and a Betasatellite Associated with Lethal Leaf Yellowing of Kalmegh (Andrographis paniculata) in Northern India

Plant Disease ◽

10.1094/pdis-08-14-0862-pdn ◽

2015 ◽

Vol 99 (2) ◽

pp. 292-292 ◽

Cited By ~ 7

Author(s):

A. Khan ◽

S. T. Saeed ◽

A. Samad

Keyword(s):

Sequence Analysis ◽

Mosaic Virus ◽

Rolling Circle Amplification ◽

Andrographis Paniculata ◽

Yellow Vein ◽

Yellow Mosaic Virus ◽

Mechanical Transmission ◽

Specific Primers ◽

Leaf Yellowing ◽

Leaf Curl

Andrographis paniculata (Family Acanthaceae), also called Kalmegh, is a medicinal herb in India well-known for its various pharmaceutical properties (1). In August 2012, during a survey in the northern parts of India, several Kalmegh plants in Barabanki District of Uttar Pradesh Province showed typical virus-like symptoms along with prominent lethal leaf yellowing. The infected plants initially showed some chlorotic streaks, which later turned completely yellow, ultimately leading to premature death. Mechanical/sap inoculation failed to transmit the pathogen. Based on the symptomology, a heavy infestation of whiteflies (Bemisia tabaci) in the infected fields, and lack of mechanical transmission, the association of a begomovirus was suspected. The disease incidence was calculated to be about 15 to 20% on the basis of plant population. Twenty samples from naturally infected plants of A. paniculata were collected from various field locations. Total genomic DNA from the symptomatic and non-symptomatic samples was isolated by the modified CTAB method (4). The initial PCR-based detection was performed using begomovirus coat protein gene specific primers (forward 5′-ATGGCGAAGCGACCAG-3′ and reverse 5′-TTAATTTGTGACCGAATCAT-3′), which generated an amplicon of 771 bp in most of the (17/20) symptomatic samples. No amplification was obtained in healthy or non-symptomatic plant samples. The full-length genome was amplified via rolling-circle amplification (RCA) according to the manufacturer's instructions using random hexamer primers and φ29 DNA polymerase. A portion of the RCA product (1 μl) was subjected to digestion with different restriction enzymes, out of which BamHI yielded DNA fragments of approximately 2.7 and 1.3 kb, corresponding to DNA-A and β satellite molecules, respectively. These fragments were eluted from the gel and cloned into the suitable restriction site of pGreen0029 vector. The positive clones were checked by restriction digestion. Twelve out of 20 clones were found to be positive and sequenced. The complete genome sequences of DNA A (2,754 bp) and β (1,366 bp) satellites were deposited in the GenBank database with the accession numbers KM359406 and KM359407, respectively. The absence of DNA-B molecule was ascertained, as no PCR amplification was detected with DNA-B-specific primers. Sequence analysis showed highest nucleotide identity (90%) with Catharanthus yellow mosaic virus (CYMV) (HE580234) and ≤85% identity with other begomoviruses of the database. Sequence analysis of the associated betasatellite showed 96% identity with Andrographis yellow vein leaf curl betasatellite (KC967282). CYMV was first reported on Catharanthus roseus with no associated betasatellite from Pakistan (2). However, this is the first report of CYMV along with a betasatellite infecting A. paniculata in India. Recently a begomovirus (Eclipta yellow vein virus) infection was reported on A. paniculata in association with Andrographis yellow vein leaf curl betasatellite from India for the first time (3); now the crop has also become a host of CYMV. Thus, this study highlights the spread of CYMV from its preliminary host to a new host plant (A. paniculata), across the South Asian countries. Therefore, it is important to take measures for the management of its transmitting vector so as to curtail the spread of the virus to new economically and commercially important crops. References: (1) S. Akbar. Altern. Med. Rev. 16:1, 2011. (2) M. Ilyas et al. Arch. Virol. 158:505, 2013. (3) A. Khan and A. Samad. Plant Dis. 98:698, 2014. (4) S. P. S. Khanuja et al. Plant Mol. Biol. Rep. 17:1, 1999.

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tRNA-Like Structure Regulates Translation of Brome Mosaic Virus RNA

Journal of Virology ◽

10.1128/jvi.78.8.4003-4010.2004 ◽

2004 ◽

Vol 78 (8) ◽

pp. 4003-4010 ◽

Cited By ~ 26

Author(s):

Sharief Barends ◽

Joëlle Rudinger-Thirion ◽

Catherine Florentz ◽

Richard Giegé ◽

Cornelis W. A. Pleij ◽

...

Keyword(s):

Coat Protein ◽

Protein Expression ◽

Mosaic Virus ◽

Dominant Role ◽

Initiation Site ◽

Plant Viruses ◽

Brome Mosaic Virus ◽

Trna Synthetase ◽

Yellow Mosaic Virus ◽

Genomic Rnas

ABSTRACT For various groups of plant viruses, the genomic RNAs end with a tRNA-like structure (TLS) instead of the 3′ poly(A) tail of common mRNAs. The actual function of these TLSs has long been enigmatic. Recently, however, it became clear that for turnip yellow mosaic virus, a tymovirus, the valylated TLSTYMV of the single genomic RNA functions as a bait for host ribosomes and directs them to the internal initiation site of translation (with N-terminal valine) of the second open reading frame for the polyprotein. This discovery prompted us to investigate whether the much larger TLSs of a different genus of viruses have a comparable function in translation. Brome mosaic virus (BMV), a bromovirus, has a tripartite RNA genome with a subgenomic RNA4 for coat protein expression. All four RNAs carry a highly conserved and bulky 3′ TLSBMV (about 200 nucleotides) with determinants for tyrosylation. We discovered TLSBMV-catalyzed self-tyrosylation of the tyrosyl-tRNA synthetase but could not clearly detect tyrosine incorporation into any virus-encoded protein. We established that BMV proteins do not need TLSBMV tyrosylation for their initiation. However, disruption of the TLSs strongly reduced the translation of genomic RNA1, RNA2, and less strongly, RNA3, whereas coat protein expression from RNA4 remained unaffected. This aberrant translation could be partially restored by providing the TLSBMV in trans. Intriguingly, a subdomain of the TLSBMV could even almost fully restore translation to the original pattern. We discuss here a model with a central and dominant role for the TLSBMV during the BMV infection cycle.

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Modifications of the Helper Component-Protease of Zucchini yellow mosaic virus for Generation of Attenuated Mutants for Cross Protection Against Severe Infection

Phytopathology ◽

10.1094/phyto-97-3-0287 ◽

2007 ◽

Vol 97 (3) ◽

pp. 287-296 ◽

Cited By ~ 45

Author(s):

Shih-Shun Lin ◽

Hui-Wen Wu ◽

Fuh-Jyh Jan ◽

Roger F. Hou ◽

Shyi-Dong Yeh

Keyword(s):

Mosaic Virus ◽

Fluorescent Protein ◽

Zucchini Yellow Mosaic Virus ◽

Chenopodium Quinoa ◽

Severe Infection ◽

Plant Viruses ◽

Cross Protection ◽

Yellow Mosaic Virus ◽

Mild Strain ◽

Helper Component

A nonpathogenic mild strain is essential for control of plant viruses by cross protection. Three amino acid changes, Arg180→Ile180 (GA mutation), Phe205→Leu205 (GB mutation), and Glu396→Asn396 (GC mutation), of the conserved motifs of the helper component-protease (HC-Pro) of a severe strain TW-TN3 of Zucchini yellow mosaic virus (ZYMV), a member of the genus Potyvirus, were generated from an infectious cDNA clone that carried a green fluorescent protein reporter. The infectivity of individual mutants containing single, double, or triple mutations was assayed on local and systemic hosts. On Chenopodium quinoa plants, the GB mutant induced necrotic lesions; the GA, GC, and GBC mutants induced chlorotic spots; and the GAB and GAC mutants induced local infection only visualized by fluorescence microscopy. On squash plants, the GA, GB, GC, and GBC mutants caused milder mosaic; the GAC mutant induced slight leaf mottling followed by recovering; and the GAB mutant did not induce conspicuous symptoms. Also, the GAC mutant, but not the GAB mutant, conferred complete cross protection against the parental virus carrying a mite allergen as a reporter. When tested on transgene-silenced transgenic squash, the ability of posttranscriptional gene silencing suppression of the mutated HC-Pro of GAC was not significantly affected. We concluded that the mutations of the HC-Pro of ZYMV reduce the degrees of pathogenicity on squash and also abolish the ability for eliciting the hypersensitive reaction on C. quinoa, and that the mutant GAC is a useful mild strain for cross protection.

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