Doon, Yaakob

Sidek, Zakaria

Sulaiman, Inon

Universiti Putra Malaysia Institutional Repository

UPM Research Report 1998: Volume 2TRANSMISSION AND SEROLOGICAL SCREENINGOF VIRAL INFECTION IN SWEET POTATO(IPOMOEA BATATASL.) LAMInon Sulaiman, Zakaria Sidek and Yaakob DoonUnillersiti Putra Malaysia. 43400 UPM. Serdang. Selangor,MalaysiaKeywords: Ipomoea batatas, virus, grafting, aphids,and serology.Introduction'Sweet potato is one of the world's important food crops,ranking seventh in total production. Although it has beenplanted in Malaysia for more than 100 years and hundreds ofsweet potato varieties are available, there is now an increas-ing interest in its cultivation in this country (Saad, 1994).According to Moyer and Salazar (1989) virtually all sweetpotatoes grown from non-tested materials revealed presenceof one or more virus. Skoglund and Smit (l994) reported vi-ruses appear to cause the greatest damage in the field andcontribute the most yield losses. Little is known about theidentity and properties of virus infecting sweet potato inMalaysia, although symptoms associated to virus infectionwere more prevalent in the field recently. The objective ofthis study is to identify the causal agent of the virus diseaseof three sweet potato cultivars that showed different symp-toms through transmission (by grafting and aphids) and se-rological screening. Finding from this study will be used forantiserum production for viral detection in field and germ-plasm collection.Materials and MethodsVirus sources used were from three infected sweet potatocultivars 053K showing chlorotic vein-banding, rugose,slightly folded and twisting symptoms; cultivar 402T leavesshowing ringspots and cultivar 470J leaves showing chloroticspots Ipomoea setosa plants, which were about a month old,were cut off about three or four leaves up from the base. Adiseased Ipomoea batatas cultivar was then cleft grafted to it.A side veneer graft was also made to some plants. Ipomoeasetosa at two to four leaf stage were also subjected to timedacquisition and inoculation feeding by aphids; Aphis crac-civora and A. gossypii. Symptoms observed on the indicatorplants as the results of the two transmission studies were re-corded. Two commercial ELISA kits namely Agdia IndirectELISA<and NCM-ELISA tests were used for serologicalstudies.42Results and DiscussionThe virus from the three sweet potato cultivars could betransmitted by grafting and insect vectors to Ipomoea setosaplants. The symptoms expressed on Ipomoea setosa weretypical of sweet potato feathery mottle virus (SPFMV), asreported previously in this indicator plant (Clark and Moyer,1988; Moyer and Salazar, 1989; Moyer and Larsen, 1991).The virus was transmitted in a non-persistent manner toIpomoea setosa plants from the three cultivars by both aphids(Aphis craccivora and Aphis gossypii). Aphis gossypii wasmore efficient than Aphis craccivora in SPFMV transmis-sion. Mean percent transmission for a range of acquisitionperiods no, 20, 30, 40, 50 and 60 sec.) was 41.7% for Aphisgossypii and 25% for Aphis craccivora. Thirty seconds ac-quisition and inoculation feeding times were found to be op- .timum for A. gossypii to transmit the virus.Both Agdia Indirect ELISA and NCM-ELISA could detectvirus from the three sweet potato cultivars used in thesestudies. However, NCM-ELISA procedure was more sensi-tive and reliable in detecting virus in low concentration ascompared with Agdia Indirect ELISA method. Since theAgdia Indirect ELISA was specific for aphid transmittedpotyvirus group, all three cultivars with different symptomswere infected by a potyvirus group.ConclusionsBased on the symptoms on the indicator plant Ipomoea se-tosa, the non-persistent manner of transmission by vectorsand the positive reactions of both ELISA procedures, it canbe concluded that the virus present was sweet potato featherymottle virus (SPFMV), which belongs to a potyvirus group.ReferencesClark, C.A. and Moyer, J.W. 1988. Compendium of sweet potatodiseases. A.P.S. Press. The American Phytopathological Society,USA. FAO. 1986. FAO production yearbook. 1985. Food andAgriculture Organisation, Rome.Moyer, J.W. and Larsen, R.C. 1991. Management of insect vectorsof viruses infecting sweet potato. pp: 341-357Jn: Sweet potatopest management: A global perspective. R. K. Jansson and K. V.Raman (Eds.).Moyer, J.W. and Salazer, L. 1989. Viruses and Viruslike Diseases ofSweet Potato. Plant Diseases. 73(6): 451-455.Saad, M.S. 1994. Sweet potato: The special crop of the world. Agro-Search. Research Bulletin. Faculty of Agriculture. UPM Vol. 1No.2:1-3Skoglund, L.G. and Smit, N.E.J.M. 1994.Major Diseases and Pestsof Sweet Potato in Eastern Africa. International Potato Center(CIP). Lima, Peru: 67.Supported by IRPA GrantOl-02-04-0175

Transmission and serological screening of viral infection in sweet potato (Ipomoea batatas L.) Lam

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Transmission and serological screening of viral infection in sweet potato (Ipomoea batatas L.) Lam

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