Read-through protein gene of potato mop-top furovirus is associated with acquisition and transmission of the virus by Spongospora Subterranea F.SP. Subterranea

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 read-through 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 read-through gene encoded on RNA 3 is involved in acquisition and transmission of PMTV by its fungal vector, S. subterranea f. sp. subterranea.