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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/2441

Authors: Eyasu, Wada
Advisors: Dr. Tileye Feyissa
Dr. Adane Abraham,
Keywords: Begomoviruses
Copyright: Jun-2010
Date Added: 4-May-2012
Abstract: ABSTRACT Tomato as well as cassava yield is limited by virus diseases and which has been one of most important constraint for production of both crops. The genus Begomovirus belongs to family Geminiviridae and has emerged as more serious constraints to varieties of crops including tomato and cassava worldwide. In addition to it, other major tomato viruses infecting tomato plant in tropical Africa have been included in the genus Tobamovirus, Tospovirus, Potyvirus and Cucumovirus. African cassava mosaic virus also causes a devastating cassava yield. To determine the incidence and prevalence of begomoviruses on tomato and cassava in Ethiopia, 570 tomato and 250 cassava leaf samples were collected from 57 tomato and 25 cassava fields respectively from October 21, 2009 to December 21, 2009. Most of the tomato fields were surveyed at East Shewa in Rift Valley and western Ethiopia whereas most cassava fields were surveyed at southern Ethiopia. The tomato samples were tested in DAS-ELISA against seven tomato infecting viruses: Tomato yellow leaf curl virus, Tomato mosaic virus, Tomato spotted wilt virus, Tomato ring spot virus-Chickadee strain, Tobacco mosaic virus, Potato virus Y and Cucumber mosaic virus. Cassava samples were tested in TAS-ELISA against African cassava mosaic virus, using universal probe which can detect all African cassava mosaic virus species so far described. Molecular technique based assays were performed based on immunocapture PCR for detection of Tomato yellow leaf curl virus, using Begomovirus DNA-A specific degenerative primer pair, Begomo_146 and Begomo_672. Immunocapture-PCR and standard PCR techniques were used to test African cassava mosaic virus, using three pairs of primers: Begomovirus DNA-A specific, Begomovirus DNA-B specific and African cassava mosaic virus DNA-A specific. Tomato samples from Rift Valley areas provided weak positive test to Tomato yellow leaf curl virus and clear positive test to Tomato mosaic virus in DAS-ELISA. All tomato samples were negative for Tomato spotted wilt virus, Tomato Ring spot virus-Chickadae strain, Tobacco mosaic virus, Potato virus Y and Cucumber Mosaic virus. The expected 520 bp PCR product of Tomato yellow leaf curl virus was obtained from samples which gave weak positive test for this virus in DAS-ELISA test. TAS-ELISA test as well as molecular technique based assays based on both methods using three pairs of primers all provided negative results for African cassava mosaic virus. Research should be broadened to include more samples. Tomato yellow leaf curl virus and Tomato mosaic virus were detected at 24.6% and 47.37% of the study area respectively. These viruses showed a distinct pattern of distribution in the surveyed areas at incidence level varying from 20% to 70%. Considering the incidence and distribution, appropriate virus management programme should be sought.
URI: http://hdl.handle.net/123456789/2441
Appears in:Thesis - Biology

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