The Rep proteins encoded by alphasatellites restore expression of a transcriptionally silenced green fluorescent protein transgene in Nicotiana benthamiana
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Alphasatellites are non-essential satellite-like components associated with geminiviruses. The precise selective advantage to a geminivirus infection of an alphasatellite remains unclear. The ability of the cotton leaf curl Multan alphasatellite (CLCuMuA)-encoded replication-associated protein (Rep) to suppress TGS was investigated by using Nicotiana benthamiana line 16-TGS (16-TGS) harbouring a transcriptionally silenced green fluorescent protein (GFP) transgene. Inoculation of 16-TGS plants with a recombinant Potato virus X (PVX) vector carrying CLCuMuA Rep resulted in restoration of GFP expression. Northern blot analysis confirmed that the observed GFP fluorescence was associated with GFP mRNA accumulation. Inoculation with PVX vectors harbouring a further six Rep proteins, encoded by genetically distinct alphasatellites, were similarly shown to result in 16-TGS plants with restored GFP expression. These results indicate that the alphasatellite-encoded Rep can restore the expression of a transcriptionally silenced GFP transgene in N. benthamiana, indicating that alphasatellites are involved in overcoming host defence.
KeywordsAlphasatellite Geminivirus RNA interference Transcriptional gene silencing
The authors are grateful to Arvind Varsani for providing the CLCuGeA and DfasA clones. QA and MS were supported by indigenous Ph.D. scholarships from the Higher Education Commission (HEC), Government of Pakistan. RWB was supported by the HEC under the “Foreign Faculty Hiring Program”.
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