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Transgenic resistance to PMTV and PVA provides novel insights to viral long-distance movement

Germundsson, Anna (2005). Transgenic resistance to PMTV and PVA provides novel insights to viral long-distance movement. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2005:105
ISBN 91-576-6904-X
[Doctoral thesis]

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The studies in this thesis describe forms of transgenic resistance to plant viruses and how they can be used for studying viral infection cycle. S. tuberosum cv. Saturna expressing the CP gene of Potato mop-top virus (PMTV) was grown in a field infested with the viruliferous vector of PMTV, S. subterranea. The incidence of PMTV-infected tubers was lower in the CP-transgenic potato than in non-transgenic potato. RNA dot-blot analysis revealed that in tubers infected with PMTV, all three RNAs were present. N. benthamiana plants expressing the CP gene of PMTV were inoculated by two different methods i) mechanical inoculation to leaves and ii) growing plants in soil infested with viruliferous S. subterranea. Results showed that the expression of the transgene-derived RNA (or CP) inhibits replication of homologous RNA 2 in transgenic N. benthamiana. Furthermore, the results showed that transgene-mediated resistance to PMTV differs in roots and leaves. Mechanical inoculation with PMTV on CP-transgenic N. benthamiana resulted in symptomless, systemic movement of RNA 1 and RNA 3, but not the CP-encoding RNA (RNA 2). These findings show that PMTV RNA 1 and RNA 3 can infect and move systemically in N. benthamiana without the CP and RNA 2. N. benthamiana transformed with the P1 and VPg cistron, respectively, of Potato virus A (PVA) displayed: i) resistance to PVA infection, ii) susceptibility, or iii) systemic infection followed by recovery from PVA infection of new leaves. Long-distance transport of PVA from lower, infected parts of recovered plants was compromised in the recovered tissue. This result suggests that PVA is moving as ribonucleoprotein complex other than virus particles. N. benthamiana transformed with a polycistronic transgene encoding the CI-NIa-CP cistrons of PVA was susceptible to PVA infection. VPg (the N-proximal part of NIa) is a well-known virulence factor of potyviruses and its possible role in suppression of RNA silencing was studied. PVA VPg was found to increase the severity of disease symptoms when expressed from a Potato virus X vector in N. benthamiana. However, PVA VPg did not show apparent RNA silencing suppression activity. The reason why the polycistronic transgene did not provide resistance could not be resolved.

Authors/Creators:Germundsson, Anna
Title:Transgenic resistance to PMTV and PVA provides novel insights to viral long-distance movement
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :November 2005
Number of Pages:51
ALLI. Germundsson, A., Sandgren, M., Barker, H., Savenkov, E.I. & Valkonen, J.P.T. 2002. Initial infection of roots and leaves reveals different resistance phenotypes associated with coat protein gene-mediated resistance to Potato mop-top virus. Journal of General Virology 83, 1201-1209. II. Savenkov, E.I., Germundsson, A., Zamyatnin, A.A. Jr., Sandgren, M. & Valkonen, J.P.T. 2003. Potato mop-top virus: the coat protein-encoding RNA and the gene for cysteine-rich protein are dispensable for systemic virus movement in Nicotiana benthamiana. Journal of General Virology 84, 1001-1005. III. Germundsson, A. & Valkonen, J.P.T. 2005. P1- and VPg-transgenic plants show similar resistance to Potato virus A and may compromise long distance movement of the virus in plant sections expressing RNA silencing-based resistance. Virus Research, accepted for publication IV. Germundsson, A., Savenkov, E.I. & Valkonen, J.P.T. 2005. VPg of Potato virus A alone does not suppress RNA silencing but affects virulence of a heterologous virus. Manuscript
Place of Publication:Uppsala
ISBN for printed version:91-576-6904-X
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F30 Plant genetics and breeding
H Protection of plants and stored products > H20 Plant diseases
Subjects:Not in use, please see Agris categories
Agrovoc terms:solanum tuberosum, plant diseases, plant viruses, potato mop top furovirus, viroses, transgenic plants, analytical methods
Keywords:Transgenic resistance, Potato mop-top virus, PMTV, Potato virus A, PVA, Nicotiana benthamiana, viral movement, pathogenesis, RNA silencing
Permanent URL:
ID Code:985
Department:(NL, NJ) > Dept. of Plant Biology and Forest Genetics (until 131231)
Deposited By: Anna Germundsson
Deposited On:21 Nov 2005 00:00
Metadata Last Modified:02 Dec 2014 10:08

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