Insect Transmission of Sweet Potato Disease Agents in Nigeria

Schaefers, G. A.; Terry, Elein

doi:10.1094/phyto-66-642

Cited by 87 publications

(61 citation statements)

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“…There was consistent change in the mean disease index between months and years across the monocrop and the intercrop fields, forming various cycles during the growth and maturity of the crop. Similar observations have been reported in Uganda and in other tropical regions (Alicia 1999;Byamukama et al 2004;Gibson et al 2004;Schaefers and Terry 1976;Wosula et al 2012). Correlations with antecedent climate factors provided opportunity to forecast pest population density (whiteflies, aphids) and therefore sweetpotato virus infection (Sseruwu et al 2015).…”

Section: Linkage Between Climatic Factors and Virus Infection Pressuresupporting

confidence: 56%

Interaction of the fluctuation of the population density of sweet potato pests with changes in farming practices, climate and physical environments: A 11-year preliminary observation from South-Kivu Province, Eastern DRCongo

Munyuli¹,

Kalimba²,

Mulangane³

et al. 2017

Open Agriculture

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Open Agriculture. 2017; 2: 495-530 determined which climatic factors may be used as best predictors of the different status of pest populations (declines, outbreaks). Farmer based data was obtained using a semi structured questionnaire administered to several of farmers. Population dynamics of sweetpotato pests were monitored year-round from 2005 to 2015 in South Kivu province, eastern DRCongo. Field monitoring (visual counts) observations (population dynamic of different soil-dwelling and surface dwelling arthropods visiting sweetpotato fields) combined with a survey of farmers' knowledge on sweetpotato pests and their practices in the management of these pests in SouthKivu Province were conducted for 11 years. Monitoring (with field observations and counts) was carried out in fields under different farming practices (monocropping and inter-cropping) in sites located at different altitudes. Similarly, data for climatic factors, for the same period, were collected from Lwiro Research center. Regression models were applied to understand the linkages between environmental factors (rainfall and temperature) and pest population dynamics. The results indicated that different varieties (local and improved ones) of sweetpotato are grown three times (3 seasons) per annum under various cropping systems (sole crop, mixed crops) in various agroecological zones at different altitudes. Various arthropod species visit the crop at its different stages of development including classically known pests (Acraea acerata, Cylas spp.) or as vectors of diseases (Bemisi tabaci, Aphis spp.). The results indicated a high fluctuation in the population density of different pests. The change in the population dynamics were characterized by gradual increase in the populations during rainy seasons followed by decline during dry seasons (hot months of the year). Significant (P<0.05) https://doi.org/10.1515/opag-2017-0054 received January 2, 2016; accepted March 19, 2017 Abstract: Sweetpotato is a major food security crop grown in eastern Democratic Republic of Congo. Its production is however limited due to high prevalence of pests and diseases among other abiotic and biotic factors. A study was designed to aid understanding the knowledge of farmers about pests and their perception about climate variability impacts, as well as documenting the phenology of sweetpotato pests (pest population dynamics) in relationship with weather factors. The paper aimed at differences were observed in the population dynamics between sole sweetpotato and mixed sweetpotato intercropping. There was a synchronization of multiple pest generations (biannual, multiannual cycles of reproduction) built up with early rains. The results indicate that rainfall and maximum temperature were critical to the survival and population built up of the pest population. High rainfall in the previous months caused increases in the population density in the subsequent months within a year. The population dynamic (seasonal occurrence) over months and years was likely to coincide ...

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Section: Linkage Between Climatic Factors and Virus Infection Pressuresupporting

confidence: 56%

Interaction of the fluctuation of the population density of sweet potato pests with changes in farming practices, climate and physical environments: A 11-year preliminary observation from South-Kivu Province, Eastern DRCongo

Munyuli¹,

Kalimba²,

Mulangane³

et al. 2017

Open Agriculture

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“…Cultivars Tanzania and New Kawogo are ranked among the popular and widely grown cultivars (Mwanga et al, 1995). Cultivar Busia was selected because it displayed recovery from sweetpotato severe mosaic disease (SPSMD), caused by co-infection of SPCSV and SPMMV (Mukasa et al, 2006 (Schaefers and Terry, 1976). The grafted I. setosa plants were observed for symptoms five weeks post-grafting.…”

Section: Methodsmentioning

confidence: 99%

Detection and elimination of sweetpotato viruses

Rukarwa

Mashingaidze²,

Kyamanywa³

et al. 2011

African Crop Science Journal

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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 RÉSUMÉEn 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 SPCSV dont le niveau d'infection était le même (8.3%). Basé sur la survie des pousses et l'efficacité de l'élimination de virus, les meilleurs résultats étaient obtenus en exposant les plantules à un regime de température de 32 o C pendant 8 heures sous obscurité et 36 o C pendant 16 heures sous lumière durant quatre semaines. La culture du bout du méristème combinée à la thermothérapie a perimis l'élimination de SPFMV et SPMMV dans 77 % des plants qui étaient au départ infectés avec des virus respectifs. Par ailleurs, l'élimination de SPCSV avait échoué.

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“…Recently, a few SPCSV isolates serologically related to the EA strain were found in Peru (Gutiérrez et al, 2003). However, SPCSV isolates from Nigeria, Israel and the USA have been found to be related to each other (Hoyer et al, 1996b;Pio-Ribeiro et al, 1996;Vetten et al, 1996) and assigned to the strain WA, named according to the original description of SPCSV as a 'chlorotic stunt'-causing agent in sweetpotatoes in Nigeria, West Africa (Schaefers & Terry, 1976). Closterovirus-like particles were later detected in sweetpotatoes showing chlorotic stunt symptoms in Nigeria (Winter et al, 1992), Israel (Cohen et al, 1992) and Kenya (Hoyer et al, 1996a, b).…”

Section: Introductionmentioning

confidence: 99%

Analysis of gene content in sweet potato chlorotic stunt virus RNA1 reveals the presence of the p22 RNA silencing suppressor in only a few isolates: implications for viral evolution and synergism

Cuellar

Tairo

Kreuze

et al. 2008

Journal of General Virology

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Sweet potato chlorotic stunt virus (genus Crinivirus) belongs to the family Closteroviridae, members of which have a conserved overall genomic organization but are variable in gene content. In the bipartite criniviruses, heterogeneity is pronounced in the 39-proximal region of RNA1, which in sweet potato chlorotic stuat virus (SPCSV) encodes two novel proteins, RNase3 (RNase III endonuclease) and p22 (RNA silencing suppressor). This study showed that two Ugandan SPCSV isolates contained the p22 gene, in contrast to three isolates of the East African strain from Tanzania and Peru and an isolate of the West African strain from Israel, which were missing a 767 nt fragment of RNA1 that included the p22 gene. Regardless of the presence of p22, all tested SPCSV isolates acted synergistically with potyvirus sweet potato feathery mottle virus (SPFMV; genus Potyvirus, family Potyviridae) in co-infected sweetpotato plants (Ipomoea batatas), which greatly enhanced SPFMV titres and caused severe sweetpotato virus disease (SPVD). Therefore, the results indicate that any efforts to engineer pathogen-derived RNA silencing-based resistance to SPCSV and SPVD in sweetpotato should not rely on p22 as the transgene. The data from this study demonstrate that isolates of this virus species can vary in the genes encoding RNA silencing suppressor proteins. This study also provides the first example of intraspecific variability in gene content of the family Closteroviridae and may be a new example of the recombination-mediated gene gain that is characteristic of virus evolution in this virus family. INTRODUCTIONViruses belonging to the family Closteroviridae have singlestranded, positive-sense RNA genomes that are the largest among plant viruses . These viruses share a conserved set of 'core' genes, but they also show a high level of variability in gene content at the 39 end of the monopartite genomes in the genera Closterovirus and Ampelovirus and at the 39 end of RNA1 in viruses of the genus Crinivirus, which have bipartite genomes . Gene content and organization of the variable 39-proximal genomic region have evolutionary implications (Karasev et al., 1996;Dolja et al., 2006), which are interesting not least because some of the genes in the 39 region encode RNA silencing suppression (RSS) proteins (Reed et al., 2003;Lu et al., 2004;Kreuze et al., 2005;Chiba et al., 2006). RSS proteins combat the fundamental antiviral resistance that is based on RNA silencing in plants (Lindbo & Dougherty, 2005). The functional similarities of the RSS proteins contrast with their very low or non-significant sequence homology with other viral and host proteins Mérai et al., 2006). It has been suggested that these characteristics might indicate a relatively recent acquisition of the genes for RSS proteins in viral genomes to counteract evolving eukaryotic host defence responses to viral pathogens (Voinnet, 2005).Sweet potato chlorotic stunt virus (SPCSV; genus Crinivirus, family Closteroviridae) is a phloem-limited, whitefly-transmitted, bipartite viru...

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Insect Transmission of Sweet Potato Disease Agents in Nigeria

Cited by 87 publications

References 0 publications

Interaction of the fluctuation of the population density of sweet potato pests with changes in farming practices, climate and physical environments: A 11-year preliminary observation from South-Kivu Province, Eastern DRCongo

Interaction of the fluctuation of the population density of sweet potato pests with changes in farming practices, climate and physical environments: A 11-year preliminary observation from South-Kivu Province, Eastern DRCongo

Detection and elimination of sweetpotato viruses

Analysis of gene content in sweet potato chlorotic stunt virus RNA1 reveals the presence of the p22 RNA silencing suppressor in only a few isolates: implications for viral evolution and synergism

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