VIRUSES IN WEEDS IN Dioscorea YAM FIELDS IN NIGERIA

Abstract

The presence of viruses in yam leaves and the presence of weeds in close proximity to yam fields have been shown to be associated with diminished tuber yield. But the precise role of weeds as alternative hosts of viruses infecting yam has not been systematically studied. Therefore, leaf samples of weeds were collected from Dioscorea yam fields in FCT-Abuja, and five States of the Guinea Savanna agro-ecological zone of Nigeria in 2009 and 2010, and analysed by Enzyme-Linked Immuno-absorbance Assay (ELISA) and Polymerase Chain Reaction for viruses. Fifty-four and 70% of samples collected during the two years, respectively, were infected with Yam mosaic virus, Cucumber mosaic virus, Cowpea mild mottle virus, Pepper venial mosaic virus, Telfeiria mosaic virus, Cowpea yellow mosaic virus and Badnavirus (DaBV). The weeds and viruses were Hibiscus esculentus Moench (YMV, CMV and CPMMV), Amaranthus spinosus Linn (CMV, YMV), Physalis angulata L (YMV, CMV), Procumbane Linn (CMV), Phyllanthus amarus Shum (YMV, CMV, CPMMV), Ludwigia abyssinica A. Rich (YMV), Galinsoga culiata L. (YMV), Eclipta prostrate Linn (YMV), Justicia flara Vahl (YMV, CMV), Euphorbia heterophylla Linn (YMV, CMV), Melanpodium divaricatum L. (YMV, CMV) and Saccivlepsis Africana Hubb (YMV), Melanpodium divaricatum L. (CPMMV), Crotalaria rutusa L. (YMV, CMV), Aspelia bussei O. Hoffin (CPMMV), Aneilema acquinotide P. Beauv (CPMMV), Pueraria phaseloides Linn (YMV), Platostoma Africana P. (YMV), Conyza summtrensis Retz (YMV, BCMV, PVMV, TeMV), Chroniolea oduratiu L. R (YMV, CYMV), Mitracarpus villosus D.C(CMV) and Sclerocarpus africanus Jacq (BCMV, PVMV, TeMV, Badnavirus). Weeds surrounding yam plants may serve as alternative hosts of viruses.La pr\ue9sence de virus dans yam laisse et la pr\ue9sence de mauvaises herbes dans une proximit\ue9 imm\ue9diate avec l\u2019igname champs auraient d\ufb \ueatre divulgu\ue9s de s\u2019associer avec un rendement de tubercules diminu\ue9e. Mais le r\uf4le pr\ue9cis des mauvaises herbes comme h\uf4te alternatif de virus infectant yam n\u2019a pas \ue9t\ue9 syst\ue9matiquement \ue9tudi\ue9. Par cons\ue9quent, les \ue9chantillons de feuilles des mauvaises herbes ont \ue9t\ue9 recueillies lors des relev\ue9s des champs igname Dioscorea en FCT-Abuja et cinq \uc9tats de la zone agro-\ue9cologique savane de Guin\ue9e du Nig\ue9ria en 2009 et 2010 et analys\ue9s par Enzyme-Linked Immuno-absorption Assay (ELISA) et r\ue9action en cha\ueene par polym\ue9rase pour virus. Cinquante-quatre et 70 % des \ue9chantillons pr\ue9lev\ue9s au cours des deux ann\ue9es ont \ue9t\ue9 infect\ue9s par le virus de la mosa\uefque Yam, Cucumber mosaic virus, virus doux de marbrure du ni\ue9b\ue9, virus de mosa\uefque v\ue9niel poivre, Telferia virus de la mosa\uefque, virus de mosa\uefque jaune de ni\ue9b\ue9 et mosa\uefque (DaBV). Les herbes et les virus ont \ue9t\ue9 Hibiscus esculentus Moench (Vitroth\ue8que, CMV et CPMMV), Amaranthus spinosus Linn (CMV, Vitroth\ue8que), Physalis angulata L. (Vitroth\ue8que, CMV), Procumbane Linn (CMV), Phyllanthus amarus Shum (Vitroth\ue8que, CMV, CPMMV), Ludwigia abyssinica A. Rich (Vitroth\ue8que), culiata L. Galinsoga . (Vitroth\ue8que), Eclipta prosterner Linn (Vitroth\ue8que), Justicia flara Vahl (Vitroth\ue8que, CMV), Euphorbia heterophylla Linn (Vitroth\ue8que, CMV), divaricatum Melanpodium L. (Vitroth\ue8que, CMV) et Saccivlepsis Africana Hubb (Vitroth\ue8que), Melanpodium divaricatum L. (CPMMV), Crotalaria rutusa L. (Vitroth\ue8que, CMV), Aspelia bussei O. Hoffin (CPMMV), Aneilema acquinotide P. Beauv (CPMMV), Pueraria phaseloides Linn (Vitroth\ue8que), Platostoma Africana P. (Vitroth\ue8que), summtrensis de Conyza Retz (VMC, Vitroth\ue8que, PVMV, TeMV), Chroniolea oduratiu L. R (Vitroth\ue8queCYMV), Mitracarpus villosus D.C(CMV) et Sclerocarpus africanus Jacq (VMC, PVMV, TeMV, mosa\uefque). Les mauvaises herbes autour d\u2019igname peuvent servir des h\uf4tes alternes de virus