Alternative hosts of cassava viruses in Kaduna and Sokoto states, Nigeria

Field surveys were conducted in 2015 wet and 2016 dry seasons to determine the occurrence of alternative hosts of cassava viruses in Kaduna and Sokoto States, Nigeria. Eighteen farms from six local Government Areas namely; Lere, Chikun, Kajuru (Kaduna State), Tureta, Shagari and Tambuwal (Sokoto State) were surveyed. Fifty- four weed samples within and around the farms were collected; Eighteen weeds were identified in wet season while 19 weeds were collected and 18 were identified during dry season. Three viruses were tested; African cassava mosaic virus (ACMV), East African cassava mosaic virus (EACMV) were detected using Triple Antibody Sandwich ELISA and Cassava Congo sequivirus using Double Antibody Sandwich ELISA. In Kaduna State, seven samples were positive to ACMV (38.8%) and four samples were positive to ACMV (22.22%) in wet and dry seasons respectively. One sample was positive to EACMV (5.56%) and mixed infection of ACMV + EACMV (5.56%). Cassava Congo sequivirus was negative in all the samples. In Sokoto State, seven weeds were positive to ACMV (38.89%) and three weeds were positive to ACMV (16.69%) in both wet and dry seasons respectively. Weeds that were identified in both wet and dry seasons were Combretum hispidum (L.) and Euphorbia hirta. Euphorbia hirta (L) was found to be an alternative host to ACMV, EACMV and their co-infection. The identification of Euphorbia hirta as new alternative host has widen the knowledge on viral inoculum. This will help to narrow the gap in spread of the disease

EFFECTS OF SERIAL PLANTING OF SEED YAM TUBERS ON VIRUS INCIDENCE AND YAM TUBER DEGENERATION

Vegetative propagation of yam ( Dioscorea spp.) with seed tubers is done to ensure uniformity of crop growth and yield. The objective of this study was to evaluate the effect of serial planting of seed yam on virus incidence and tuber degeneration in the Southern Guinea Savanna agro-ecologies of Nigeria. This study was conducted during the wet seasons of 2010 to 2012 at Kwara State and Abuja Federal Capital Territory (Abuja-FCT) in Nigeria. TDa 05/00129 and TDr 89/02665 yam bred lines from the International Institute of Tropical Agriculture, Ibadan, and three popular local varieties from each of Kwara State and Abuja Federal Capital Territory (Abuja- FCT) were used in the study. Harvested seed yams were tested for Yam mosaic virus (YMV), Yam mild mottle virus (YMMV), Dioscorea alata bacilliform viruses (DaBV) and Cucumber mosaic virus (CMV). Data obtained for germination percentage, virus incidence and tuber yields were subjected to ANOVA with mean separation done using Tukey HSD method in SPSS version 24. Viruses YMV, YMMV and DaBV were detected in seed yam as single or mixed infections. High virus incidence was associated with low tuber yield while low virus infection was associated with high tuber yield for most yam varieties. However, TDa 05/00129 produced high tuber yield inspite of high incidence of viruses in the tubers, indicating adaptation of this variety. There was progressive increase in virus population in yam seeds from the first to the third year of study with concurrent degeneration of seed yam and low yield at harvest.La multiplication v\ue9g\ue9tative de l\u2019igname (esp\ue8ces de dioscorea ) avec des tubercules de graine est faite pour assurer l\u2019uniformit\ue9 de la croissance de culture et pour rapporter. L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9valuer l\u2019effet de la plantation p\ue9riodique de l\u2019igname de graine sur la d\ue9g\ue9n\ue9rescence d\u2019incidence et de tubercule de virus en agro\ue9cologie du sud de la savane de la Guin\ue9e du Nig\ue9ria. Cette \ue9tude a \ue9t\ue9 entreprise pendant les saisons des pluies de 2010 \ue0 2012 \ue0 l\u2019\ue9tat de Kwara et au territoire capital f\ue9d\ue9ral d\u2019Abuja (Abuja-FCT) au Nig\ue9ria. TDa 05/00129 et TDr 89/02665 igname multipli\ue9e raye de l\u2019institut international de l\u2019agriculture tropicale, Ibadan, et trois vari\ue9t\ue9s locales populaires de chacun de l\u2019\ue9tat de Kwara et du territoire capital f\ue9d\ue9ral d\u2019Abuja (Abuja-FCT) ont \ue9t\ue9 employ\ue9es dans l\u2019\ue9tude. Des ignames moissonn\ue9es de graine ont \ue9t\ue9 examin\ue9es virus pour le virus doux du virus de mosa\uefque d\u2019igname (YMV), virus ignifuge de l\u2019igname (YMMV), les virus bacilliformes de dioscorea alata (DaBV) et de concombre mosa\uefque (CMV). Des donn\ue9es obtenues pour le pourcentage de germination, l\u2019incidence de virus et les rendements de tubercule ont \ue9t\ue9 analys\ue9es utilisant ANOVA avec la m\ue9thode moyenne de Tukey HSD de s\ue9paration dans la version 24 de SPSS. Des virus YMV, YMMV et DaBV ont \ue9t\ue9 d\ue9tect\ue9s en igname de graine en tant qu\u2019infections simples ou m\ue9lang\ue9es. L\u2019incidence \ue9lev\ue9e de virus a \ue9t\ue9 associ\ue9e au bas rendement de tubercule tandis que la basse infection de virus \ue9tait associ\ue9e au rendement \ue9lev\ue9 de tubercule pour la plupart des vari\ue9t\ue9s d\u2019igname. Cependant, TDa 05/00129 a produit le rendement \ue9lev\ue9 de tubercule malgr\ue9 l\u2019incidence \ue9lev\ue9e des virus dans les tubercules, indiquant l\u2019adaptation de cette vari\ue9t\ue9. Il y avait augmentation progressive de population de virus pendant graines d\u2019igname d\ue8s la d\ue9but \ue0 la troisi\ue8me ann\ue9e d\u2019\ue9tude avec la d\ue9g\ue9n\ue9rescence concourante de l\u2019igname de graine et du bas rendement \ue0 la r\ue9colte

First report of maize yellow mosaic virus infecting sugarcane (Saccharum spp.) and itch grass (Rottboellia cochinchinensis) in Nigeria

Article purchased; Published online: 9 May 2017During routine surveys conducted from February to July 2015 in the northern guinea savannah region of Nigeria, sugarcane and itch grass (Rottboellia cochinchinensis) plants showing virus-like mosaic symptoms were encountered in farmers’ sugarcane fields in Kaduna State. Symptomatic leaf tissue samples from five randomly selected plants (sugarcane = 4; itch grass = 1) were dried and stored under CaCl2 at room temperature then shipped to Texas A&M AgriLife Research and Extension Center, Weslaco, TX, with USDA-APHIS-PPQ permit (P526P-14-04321) for further analysis. The MagMAX-96 viral RNA isolation kit (Thermo Fisher) was used to isolate total nucleic acid (TNA) from each sample and from a sample subset consisting of pooled leaf tissue materials from both plants. TNA aliquot from the pooled sample was subjected to ribosomal RNA depletion and cDNA library construction using a TruSeq Stranded Total RNA with Ribo-Zero Plant kit (Illumina), then sequenced on the Illumina NextSeq 500 platform. The raw high-throughput sequencing (HTS) reads were analyzed as previously described (Alabi et al. 2015), generating ∼43.5 million Illumina reads (76 nucleotides [nt] in length), of which 31,486 de novo assemble

VIRUSES IN WEEDS IN Dioscorea YAM FIELDS IN NIGERIA

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

Survey for incidence of "Okra mosaic virus" in northern Nigeria and evidence for its transmission by beetles: short communication

En 2003 y 2004 se llevó a cabo una prospección de síntomas del virus del mosaico del kimbombó (OkMV, género Tymovirus) en plantas de kimbombó (Abelmoschus esculentus) en tres localidades del norte de Nigeria. La incidencia de OkMV más alta se detectó en Samaru (16,50 y 17,10% en 2003 y 2004, respectivamente), seguido de Shika (13,02 y 14,82%) y Bomo (12,31 y 8,10%). En las tres localidades la severidad de la enfermedad siguió la misma tendencia. Escarabajos de Podagrica spp. naturalmente infectados fueron vectores eficientes en la transmisión de OkMV.A two year survey was conducted in 2003 and 2004 in okra (Abelmoschus esculentus) plants for Okra mosaic virus (OkMV; genus Tymovirus) symptoms at three locations in northern Nigeria. It showed that the highest incidence of OkMV occurred at Samaru (16.50 and 17.10% in 2003 and 2004, respectively), followed by Shika (13.02 and 14.82%) and Bomo (12.31 and 8.10%). Disease severity followed the same trend. Beetles of Podagrica spp. naturally infected were efficient vectors in the transmission of OkMV

Comparison of transmission abilities of four Cicadulina species vectors of maize streak virus from Nigeria

Four Cicadulina species [Cicadulina arachidis China, Cicadulina dabrowskii Webb, Cicadulina mbila (Naude), and Cicadulina storeyi China (Homoptera: Cicadellidae)] found during field surveys in 1997–1999 across five ecological zones in Nigeria were reared in screenhouses and females were used in a study to compare their abilities to transmit Maize streak virus (Geminiviridae: genus Mastrevirus) from maize to maize using the susceptible variety Pool 16. The results showed that for both acquisition access feeding periods (AAP) and inoculation access feeding periods (IAP), transmission efficiencies decreased in the following order: C. storeyi > C. mbila > C. arachidis > C. dabrowskii. The transmission efficiencies of these vectors increased with longer feeding periods, as the means of susceptible test plants that showed Mastrevirus symptoms for both acquisition and IAPs were higher for 24 and 48 h than for 1 and 2 h for all four species studied. The epidemiological implications of these differences in transmission abilities are discussed

Short communication: cotton cultivars with moderate resistance to African cotton mosaic virus

A 3 year screening of 25 long staple cotton cultivars for resistance to African cotton mosaic virus (ACMoV) conducted in northern Nigeria during the 1999-2001 wet seasons indicated that no cultivar was immune or resistant. Two cultivars, Pima S1 and Pima S4 were moderately resistant (16% infection), four cultivars Pima S2, Pima S3, Giza 45 and Giza 69 were moderately susceptible (31% infection), while the remaining 19 cultivars were highly susceptible. The moderately resistant cultivars are high yielding, have high quality lint characteristics such as crin percentage, bundle strength, and micronaire fineness. They can be used to reduce the menace caused by ACMoV on cotton in Nigeria

Viruses in weeds in Dioscorea yam fields in Nigeria

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.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.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.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.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.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

Identification and molecular characterization of a novel sugarcane streak mastrevirus and an isolate of the A-strain of maize streak virus from sugarcane in Nigeria

Published online: 04 Nov 2016Sugarcane and maize plants showing symptoms typical of those described for the so-called “African streak viruses” (AfSVs) were encountered during field surveys conducted from February to July 2015 to document viruses infecting both crops across the northern Guinea savannah region of Nigeria. As part of this study, two categories of complete mastrevirus-like genome sequences were obtained from nine samples (maize = 2; sugarcane = 7). In pairwise comparisons, the full-length genomes of the first sequence category (2,687 nt each; maize = 2; sugarcane = 2) shared 96 to 99% identity with global isolates of the A-strain of maize streak virus (MSV-A), indicating that sugarcane may also serve as a reservoir host to MSV-A. Analysis of the complete genomes belonging to the second sequence category (2,757 nt each; sugarcane = 5) showed that they shared 42 to 67% identity with their closest AfSV relatives, thus indicating that they represent sequences of a novel mastrevirus. Both sequence categories shared 61-62% sequence identity with each other. Further analysis revealed that the novel sugarcane-infecting virus, tentatively named as sugarcane chlorotic streak virus (SCSV), arose from a putative interspecific recombination event involving two grass-infecting mastreviruses, eragrostis streak virus and urochloa streak virus, as putative parental sequences. The results of this study add to the repertoire of diverse AfSVs present in cereal and sugarcane mixed cropping landscapes in the northern Guinea savannah region of Nigeria, with implications for disease epidemiology