Browsing by Author "Chiunga, Evangelista"

Potato leaf roll virus (PLRV), Potato virus Y (PVY), Potato virus X (PVX), Potato virus S (PVS), Potato virus A (PVA), and Potato virus M (PVM) are widely distributed in potato (Solanum tuberosum) all over the world. This study was conducted to establish if these viruses also infect potato in Mbeya region, Tanzania. A total of 219 potato leaf samples from 13 farmers’ fields were collected. Of these, 20 samples were pressed on FTA cards. Samples were screened for viruses by Double Antibody Sandwich Enzyme Linked Immunosorbent Assay (DAS-ELISA). Those which were pressed on FTA cards were further analysed by Reverse Transcription Polymerase Chain Reaction (RT-PCR). Virus-like symptoms such as yellowish-green mosaic, leaf rolling and vein necrosis were observed and recorded at the time of field sample collection. DAS-ELISA results suggested the occurrence of all six viruses in samples from Mbeya region. RT-PCR analysis confirmed the presence of these viruses except PVY. PVS and PLRV were the most prevalent viruses. Complete coat proteins (CP) encoding sequence of five viruses (PLRV, PVX, PVA, PVS and PVM) were sequenced. Blast searches detected presence of sequences in the GenBank sharing nucleotide sequence identities of 94%-100% with isolates of viruses sequenced in this study. The complete CP sequences of the aforementioned viruses from the current study were closely related with virus isolates from different countries. The Tanzania isolates of PLRV, PVX, PVA, PVS and PVM were each suggested to belong to the one group as well as one isolate. These results are important in seed potato multiplication systems in Tanzania for improving seed quality in the local seed potato chain, an important service currently lacking to potato farmers in Tanzania.