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READ-THROUGH PROTEIN GENE OF POTATO MOP-TOP FUROVIRUS IS ASSOCIATED WITH ACQUISITION AND TRANSMISSION OF THE VIRUS BY SPONGOSPORA SUBTERRANEA F.SP. SUBTERRANEA

MOHAMMED ARIF, BRIAN REAVY* AND LESLEY TORRANCE*

Abstract: Spontaneous deletion was detected in read-through domain of potato mop-top furovirus (PMTV) RNA 3 of isolate T by reverse transcription-polymerase chain reaction (RT-PCR). PCR amplification of readthrough of PMTV-T and comparison with PMTV-S, a full-length isolate, indicated ^˜700 nucleotides difference in size but no difference in coat protein gene. Sequence analysis of the 5'-end of the read-through gene of PMTV-T relative to that of PMTV-S occurs in 3' -half of the gene and is associated with loss of transmission by the fungus vector, Spongospora subterranea f. sp. subterranea. A mono-fungal S. subterranea f. sp. subterranea was unable to acquire and transmit PMTV-T which had ^˜700 nucleotides deletion in 5'-half of read-through domain of PMTV RNA 3, while PMTV-S with full-length read-through gene was efficiently acquired and transmitted by the same fungus cultures. These results indicated that readthrough gene encoded on RNA 3 is involved in acquisition and transmission of PMTV by its fungal vector, S. subterranea f. sp. subterranea.

Department of Plant Pathology, N. W.F.P. Agricultural University, Peshawar-25000, Pakistan.
Department of Virology, Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA, U.K.