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. 2010 Mar;11(2):245-54.
doi: 10.1111/j.1364-3703.2009.00601.x.

The hypersensitive response induced by the V2 protein of a monopartite begomovirus is countered by the C2 protein

Muhammad Mubin  1 , Imran Amin, Luqman Amrao, Rob W Briddon, Shahid Mansoor
Affiliations

The hypersensitive response induced by the V2 protein of a monopartite begomovirus is countered by the C2 protein

Muhammad Mubin et al. Mol Plant Pathol. 2010 Mar.

Abstract

A functional analysis of the V2 protein of two monopartite begomoviruses, Papaya leaf curl virus (PaLCuV) and Cotton leaf curl Kokhran virus (CLCuKoV), has been performed. Expression of the V2 gene from a Potato virus X (PVX) vector resulted in severe leaf curling followed by a hypersensitive response (HR) in Nicotiana benthamiana and N. tabacum, demonstrating that the V2 protein is a pathogenicity determinant and a target of host defence responses. Agroinfiltration of a PVX vector expressing the V2 protein resulted in cell death in the infiltrated area. Subsequently, a systemic HR developed that was associated with the long-distance spread of the virus and led to the death of the plant. V2 amino acid sequences encompassing a conserved putative protein kinase C (PKC) phosphorylation motif were shown to be essential for the elicitation of cell death. In co-inoculation experiments, the transient expression of the C2 protein of PaLCuV or Cotton leaf curl Multan virus under the control of the Cauliflower mosaic virus 35S promoter inhibited the HR induced by V2 in the agroinfiltrated area. These findings demonstrate that the V2 protein of monopartite begomoviruses is a pathogenicity determinant and induces an HR that can be suppressed by the C2 protein. The induction and suppression of HR have been demonstrated previously in bipartite begomoviruses and our results extend this to monopartite begomoviruses.

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Figures

Figure 1
Figure 1
The hypersensitive response of Nicotiana benthamiana to V2 expression. (A) A N. benthamiana plant infected with PaV2/PVX showing cell death in the agroinfiltrated area (indicated by the arrows) as well as on systemic leaves. (B) A N. benthamiana plant infected with the PVX vector. The damage caused by inoculation is indicated by the arrow, but there is no cell death in the surrounding inoculated tissue. (C) A N. benthamiana plant infected with PaV2AS/PVX. The inoculated leaf is indicated by an arrow. (D) A N. benthamiana leaf inoculated with PaV2/35s showing cell death in the inoculated area. (E) A N. benthamiana plant agroinfiltrated with PaV2/PVXMD (the arrow indicates necrosis in the inoculated area). (F) A N. benthamiana plant infected with KoV2/PVX showing cell death in the agroinfiltrated areas (indicated by the arrows). Nicotiana tabacum leaves inoculated with PaV2/PVX (G) and PVX (H), and treated with trypan blue. After clearing with chloral hydrate, cells in the PaV2/PVX‐inoculated leaf retain the dye, confirming cell death.
Figure 2
Figure 2
Constructs used in the analysis and comparison of (A)V2 sequences. (A) Potato virus X (PVX)‐based expression cassettes of V2 of PaLCuV. The deletion mutants of V2 of PaLCuV are indicated with their amino acid coordinates. M and formula image are the start and stop codons, respectively. The positions of the putative protein kinase C motif (‡) and CxC motif (◊) are indicated. HR, hypersensitive response. (B) Alignment of the predicted amino acid sequences of the V2 proteins of PaLCuV‐PK[PK:Cot:02] (AJ436992) and CLCuKoV‐Fai[PK:Fai1] (AJ496286) with the V2 proteins of other selected begomoviruses: Tomato yellow leaf curl virus (TYLCV) (AF260331), South African cassava mosaic virus (SACMV‐[ZW:Muz]; AJ575560), Cotton leaf curl Multan virus (CLCuMV‐Fai[PK:Fai2]; AJ496287), Tomato leaf curl New Delhi virus (ToLCNDV‐IN[IN:ND:Svr:92]; U15015) and East African cassava mosaic Cameroon virus (EACMCV‐CM[CM:98]; AF112354). Gaps (‐) were introduced to optimize the alignment. The position of a predicted putative protein kinase C motif (TxR; coordinates 91–93 of the alignment) and the CxC motif (coordinates 116–118 of the alignment) mutated by Padidam et al., (1996) and Zrachya et al., (2007) are shown. The precise position of the initiation methionine of (A)V2 has not been determined. The V2 open reading frame of PaLCV has the capacity to encode an additional 32 amino acids at the N‐terminus in comparison with the other viruses.
Figure 3
Figure 3
Deletion analysis of PaLCuV V2 and suppression of the V2‐elicited hypersensitive response (HR) by C2. Nicotiana benthamiana plants infected with PaV2dmN32/PVX (A), PaV2dmN60/PVX (B), PaV2dmC60/PVX (C; the inoculated leaf is indicated by an arrow), PaV2dmC119/PVX (D), PaV2dmC50/PVX (E) and PaV2dmC40/PVX (F). Leaves of N. tabacum plants infiltrated with PaV2/PVX (H) and either PaC2/35S (G) or MuC2/35S (J) in the presence of PaV2/PVX. (K) A N. tabacum plant infiltrated with MuC2/35S (the agroinfiltrated area is indicated by an arrow). (I) A N. tabacum plant inoculated with PaV2/PVX showing systemic leaf curling and HR (indicated by an arrow).
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References

    1. Baker, B. , Zambryski, P. , Staskawicz, B. and Dinesh‐Kumar, S.P. (1997) Signaling in plant–microbe interactions. Science, 276, 726–733. - PubMed
    1. Balague, C. , Lin, B. , Alcon, C. , Flottes, G. , Malmstrom, S. , Kohler, C. , Neuhaus, G. , Pelletier, G. , Gaymard, F. and Roby, D. (2003) HLM1, an essential signaling component in the hypersensitive response, is a member of the cyclic nucleotide‐gated channel ion channel family. Plant Cell, 1, 365–379. - PMC - PubMed
    1. Bisaro, D.M. (2006) Silencing suppression by geminivirus proteins. Virology, 344, 158–168. - PubMed
    1. Bonneau, L. , Ge, Y. , Drury, G.E. and Gallois, P. (2008) What happened to plant caspases? J. Exp. Bot. 59, 491–499. - PubMed
    1. Briddon, R.W. and Stanley, J. (2006) Sub‐viral agents associated with plant‐infecting single‐stranded DNA viruses. Virology, 344, 198–210. - PubMed

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