A Surface Loop of the Potato Leafroll Virus Coat Protein Is Involved in Virion Assembly, Systemic Movement, and Aphid Transmission

ABSTRACT Two acidic domains of the Potato leafroll virus (PLRV) coat protein, separated by 55 amino acids and predicted to be adjacent surface features on the virion, were the focus of a mutational analysis. Eleven site-directed mutants were generated from a cloned infectious cDNA of PLRV and delivered to plants by Agrobacterium-mediated mechanical inoculation. Alanine substitutions of any of the three amino acids of the sequence EWH (amino acids 170 to 172) or of D177 disrupted the ability of the coat protein to assemble stable particles and the ability of the viral RNA to move systemically in four host plant species. Alanine substitution of E109, D173, or E176 reduced the accumulation of virus in agrobacterium-infiltrated tissues, the efficiency of systemic infection, and the efficiency of aphid transmission relative to wild-type virus, but the mutations did not affect virion stability. A structural model of the PLRV capsid predicted that the amino acids critical for virion assembly were located within a depression at the center of a coat protein trimer. The other amino acids that affected plant infection and/or aphid transmission were predicted to be located around the perimeter of the depression. PLRV virions play key roles in phloem-limited virus movement in plant hosts as well as in transport and persistence in the aphid vectors. These results identified amino acid residues in a surface-oriented loop of the coat protein that are critical for virus assembly and stability, systemic infection of plants, and movement of virus through aphid vectors.

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Host-Dependent Requirement for the Potato leafroll virus 17-kDa Protein in Virus Movement

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2002.15.10.1086 ◽

2002 ◽

Vol 15 (10) ◽

pp. 1086-1094 ◽

Cited By ~ 47

Author(s):

Lawrence Lee ◽

Peter Palukaitis ◽

Stewart M. Gray

Keyword(s):

Amino Acids ◽

Solanum Tuberosum ◽

Nicotiana Benthamiana ◽

Systemic Infection ◽

Potato Leafroll Virus ◽

Virus Movement ◽

Wild Type ◽

Mature Leaves ◽

Leafroll Virus ◽

Virus Distribution

The requirement for the 17-kDa protein (P17) of Potato leafroll virus (PLRV) in virus movement was investigated in four plant species: potato (Solanum tuberosum), Physalis floridana, Nicotiana benthamiana, and N. clevelandii. Two PLRV P17 mutants were characterized, one that does not translate the P17 and another that expresses a P17 missing the first four amino acids. The P17 mutants were able to replicate and accumulate in agroinoculated leaves of potato and P. floridana, but they were unable to move into vascular tissues and initiate a systemic infection in these plants. In contrast, the P17 mutants were able to spread systemically from inoculated leaves in both Nicotiana spp., although the efficiency of infection was reduced relative to wild-type PLRV. Examination of virus distribution in N. benthamiana plants using tissue immunoblotting techniques revealed that the wild-type PLRV and P17 mutants followed a similar movement pathway out of the inoculated leaves. Virus first moved upward to the apical tissues and then downward. The P17 mutants, however, infected fewer phloem-associated cells, were slower than wild-type PLRV in moving out of the inoculated tissue and into apical tissues, and were unable to infect any mature leaves present on the plant at the time of inoculation.

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Aphid Acquisition and Cellular Transport of Potato leafroll virus-like Particles Lacking P5 Readthrough Protein

Phytopathology ◽

10.1094/phyto.2000.90.10.1153 ◽

2000 ◽

Vol 90 (10) ◽

pp. 1153-1161 ◽

Cited By ~ 34

Author(s):

F. E. Gildow ◽

B. Reavy ◽

M. A. Mayo ◽

G. H. Duncan ◽

J. A. T. Woodford ◽

...

Keyword(s):

Coat Protein ◽

Spodoptera Frugiperda ◽

Recombinant Baculovirus ◽

Potato Leafroll Virus ◽

Cellular Transport ◽

Transcellular Transport ◽

Virus Like Particles ◽

Aphid Vectors ◽

Leafroll Virus ◽

Readthrough Protein

Lepidopteran cells (Spodoptera frugiperda) produced isometric virus-like particles (VLP) when infected with a recombinant baculovirus Ac61 that contained the Potato leafroll virus (PLRV) coat protein gene modified with an N-terminal histidine tag (P3-6H). Cells infected with AcFL, a recombinant baculovirus that expressed cDNA copies of the PLRV genome RNA, did not produce virus-like particles (VLP). In cell lines doubly infected with Ac61 and AcFL, VLP were formed that contained PLRV-RNA packaged in P3-6H coat protein (FL). Both the P3-6H and the FL particles were morphologically indistinguishable from particles of PLRV despite the fact that they lacked the P5 readthrough protein present in wild-type PLRV. When aphids (Myzus persicae) were fed on, or injected with, purified PLRV, or VLP of either type (FL or P3-6H) and examined by electron microscopy, no differences were observed among treatments for particle endocytosis, transcellular transport, or exocytosis at the aphid midgut or accessory salivary glands. Particles were observed in the salivary canals and in the salivary duct leading out of the aphid. These results suggest that P5 readthrough protein of PLRV may not be essential for cellular transport of virus through aphid vectors.

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Green peach aphid and potato leafroll virus: transmission and control

сборник статей всероссийской научной конференции с международным участием "Растениеводство и луговодство" ◽

10.26897/978-5-9675-1762-4-2020-178 ◽

2020 ◽

Author(s):

R.A. Bagrov ◽

◽

V.I. Leunov

Keyword(s):

Myzus Persicae ◽

Green Peach Aphid ◽

Virus Transmission ◽

Potato Leafroll Virus ◽

Factors Affecting ◽

Potato Viruses ◽

Tuber Necrosis ◽

Aphid Vectors ◽

Leafroll Virus ◽

And Control

The mechanisms of transmission of potato viruses from plants to aphid vectors and from aphids to uninfected plants are described, including the example of the green peach aphid (Myzus persicae, GPA). Factors affecting the spreading of tuber necrosis and its manifestation on plants infected with potato leafroll virus (PLRV) are discussed. Recommendations for PLRV and GPA control in the field are given.

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Nucleotide sequence of the potato leafroll virus coat protein gene

Nucleic Acids Research ◽

10.1093/nar/17.4.1768 ◽

1989 ◽

Vol 17 (4) ◽

pp. 1768-1768 ◽

Cited By ~ 2

Author(s):

B. Prill ◽

E. Maiss ◽

U. Timpe ◽

R. Casper

Keyword(s):

Nucleotide Sequence ◽

Coat Protein ◽

Coat Protein Gene ◽

Protein Gene ◽

Potato Leafroll Virus ◽

Virus Coat Protein ◽

Virus Coat ◽

Leafroll Virus

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A Nonviral Peptide Can Replace the Entire N Terminus of Zucchini Yellow Mosaic Potyvirus Coat Protein and Permits Viral Systemic Infection

Journal of Virology ◽

10.1128/jvi.75.14.6329-6336.2001 ◽

2001 ◽

Vol 75 (14) ◽

pp. 6329-6336 ◽

Cited By ~ 26

Author(s):

T. Arazi ◽

Y. M. Shiboleth ◽

A. Gal-On

Keyword(s):

Amino Acids ◽

Coat Protein ◽

Foot And Mouth Disease ◽

Systemic Infection ◽

Deletion Mutants ◽

Amino Acid Residues ◽

Amino Terminal ◽

Immunogenic Epitope ◽

Mouth Disease Virus ◽

N Terminus

ABSTRACT Systematic deletion and peptide tagging of the amino-terminal domain (NT, ∼43 amino acids) of an attenuated zucchini yellow mosaic potyvirus (ZYMV-AGII) coat protein (CP) were used to elucidate its role in viral systemic infection. Deletion mutants truncated by 8, 13, and 33 amino acid residues from the CP-NT 5′ end were systemically infectious and produced symptoms similar to those of the AGII virus. Tagging these deletion mutants with either human c-Myc (Myc) or hexahistidine peptides maintained viral infectivity. Similarly, addition of these peptides to the intact AGII CP-NT did not affect viral life cycle. To determine which parts, if any, of the CP-NT are essential for viral systemic infection, a series of Myc-tagged mutants with 8 to 43 amino acids removed from the CP-NT were constructed. All Myc-tagged CP-NT deletion mutants, including those from which virtually all the viral CP-NT had been eliminated, were able to encapsidate and cause systemic infection. Furthermore, chimeric viruses with deletions of up to 33 amino acids from CP-NT produced symptoms indistinguishable from those caused by the parental AGII virus. In contrast to CP-NT Myc fusion, addition of the foot-and-mouth disease virus (FMDV) immunogenic epitope to AGII CP-NT did not permit systemic infection. However, fusion of the Myc peptide to the N terminus of the FMDV peptide restored the capability of the virus to spread systemically. We have demonstrated that all CP-NT fused peptides were exposed on the virion surface, masking natural CP immunogenic determinants. Our findings demonstrate that CP-NT is not essential for ZYMV spread and that it can be replaced by an appropriate foreign peptide while maintaining systemic infectivity.

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The Three Essential Motifs in P0 for Suppression of RNA Silencing Activity of Potato leafroll virus Are Required for Virus Systemic Infection

Viruses ◽

10.3390/v11020170 ◽

2019 ◽

Vol 11 (2) ◽

pp. 170 ◽

Cited By ~ 5

Author(s):

Mamun-Or Rashid ◽

Xiao-Yan Zhang ◽

Ying Wang ◽

Da-Wei Li ◽

Jia-Lin Yu ◽

...

Keyword(s):

Amino Acid ◽

Gene Silencing ◽

Rna Silencing ◽

Systemic Infection ◽

Rna Degradation ◽

Potato Leafroll Virus ◽

Posttranscriptional Gene Silencing ◽

Conserved Region ◽

Leafroll Virus ◽

The Impact

Higher plants exploit posttranscriptional gene silencing as a defense mechanism against virus infection by the RNA degradation system. Plant RNA viruses suppress posttranscriptional gene silencing using their encoded proteins. Three important motifs (F-box-like motif, G139/W140/G141-like motif, and C-terminal conserved region) in P0 of Potato leafroll virus (PLRV) were reported to be essential for suppression of RNA silencing activity. In this study, Agrobacterium-mediated transient experiments were carried out to screen the available amino acid substitutions in the F-box-like motif and G139/W140/G141-like motif that abolished the RNA silencing suppression activity of P0, without disturbing the P1 amino acid sequence. Subsequently, four P0 defective mutants derived from a full-length cDNA clone of PLRV (L76F and W87R substitutions in the F-box-like motif, G139RRR substitution in the G139/W140/G141-like motif, and F220R substitution in the C-terminal conserved region) were successfully generated by reverse PCR and used to investigate the impact of these substitutions on PLRV infectivity. The RT-PCR and western blot analysis revealed that these defective mutants affected virus accumulation in inoculated leaves and systemic movement in Nicotiana benthamiana as well as in its natural hosts, potato and black nightshade. These results further demonstrate that the RNA silencing suppressor of PLRV is required for PLRV accumulation and systemic infection.

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