Detection and Elimination of Sweetpotato Viruses

• Published in: African crop science journal 2011-08, Vol.18 (4)
• Main Authors: Rukarwa, R. J, Mashingaidze, A.B, Kyamanywa, S, Mukasa, S.B
• Format: Article
• Language: English
• Subjects: Multiplex RT-PCR, thermotherapy, tissue culture; Multiplex RT-PCR, thermothérapie, culture de tissue
• ISSN: 1021-9730; 2072-6589; 2072-6589
• DOI: 10.4314/acsj.v18i4.68651

In sub-Saharan Africa, sweetpotato ( Impomoea batatas L.) production is greatly constrained by sweetpotato virus disease (SPVD) complex. This study was conducted to assess the incidence of viruses in healthy-looking sweetpotato in Uganda and to optimise modern technologies for virus diagnosis. A collection of healthy-looking sweetpotato vines from central Uganda were serologically assayed for sweetpotato viruses and the positive samples were confirmed by RT-PCR. A multiplex RT-PCR assay was optimised for simultaneous detection of Sweet potato chlorotic stunt virus (SPCSV), Sweet potato feathery mottle virus (SPFMV) and Sweet potato mild mottle virus (SPMMV). The use of in vitro thermotherapy was also investigated as a means of eliminating sweetpotato viruses. Four viruses namely SPCSV, SPFMV, SPMMV and SPCFV were detected mostly as single infections in the healthy looking plants. SPCSV (70. 6%) recorded highest incidence followed by co-infection of SPFMV and SPCSV (8.3%). Based on shoot survival and effectiveness of virus elimination, the best results were obtained by exposing plantlets to daily temperature regime of 32 °C for 8 hr of darkness and 36 °C for 16 hr of light for four weeks. Meristem-tip culture combined with thermotherapy allowed elimination of SPFMV and SPMMV in 77% of plants that were previously infected with the respective viruses. However, elimination of SPCSV was unsuccessful. En Afrique sub saharienne, la production de la patate douce ( Impomoea batatas L.) est grandement affectée par un complexe de maladies de virus (SPVD). Cette étude était conduite pour évaluer l'incidence maladie des virus sur des boutures apparemment saines de la patate douce en Ouganda et optimiser les technologies pour diagnostic de virus. Des boutures apparemment saines de patate douce collectées au centre de l'Ouganda étaient sérologiquement testées et les échantillons infectés étaient confirmés par RT-PCR. Un essai multiplexe RT-PCR était optimisé pour la detection simultanée du virus du rabougrissement chlorotique de la patate douce (SPCSV), le virus de la marbrure duveteuse de la patate (SPSMV) et le virus de marbrure modérée de la patate douce (SPMMV). L'usage de la thermothérapie in vitro était aussi testé comme moyen d'élimination des virus de la patate. Quatre virus dont SPCSV, SPFMV, SPMMV et SPCFV étaient detectés surtout comme seules infections des plantes apparemment saines. Le SPCSV (70. 6%) avait présenté une incidence élevée, suivi de SPFMV et SPC