scholarly journals Resistance of Four Inbred Maize Lines to Inoculation with 20 Isolates of Maize streak virus from Zimbabwe

Plant Disease ◽  
2006 ◽  
Vol 90 (12) ◽  
pp. 1485-1489 ◽  
Author(s):  
S. Mawere ◽  
V. Vincent ◽  
J. De Meyer ◽  
K. V. Pixley
Keyword(s):  
Symptom Severity ◽  
Germ Plasm ◽  
Inbred Lines ◽  
Maize Streak Virus ◽  
Sub Saharan Africa ◽  
Streak Virus ◽  
Symptom Scores ◽  
Sub Saharan ◽  
The Stability ◽  
Important Disease

Maize streak is the most widespread and important disease of maize in sub-Saharan Africa. Maize streak virus (MSV)-resistant maize germ plasm is available in several countries, but little is known about the stability of its resistance to MSV strains that may differ from one region to another. We used four maize inbred lines (CML312, CML206, CML216, and MSR) known to differ widely for their resistance to MSV in Harare, and evaluated their resistance to 20 MSV isolates collected from the wild during 2 years at locations across Zimbabwe. Maize streak development and symptom severity were evaluated in replicated greenhouse experiments using artificial inoculation via viruliferous leafhoppers. All 20 MSV isolates induced maize streak symptoms on moderately and highly susceptible genotypes by about 1 week after inoculation (WAI). Differences among isolates for severity of early maize streak symptoms were ephemeral, and resistance was accurately differentiated by all isolates by 3 to 4 WAI. Differences in final maize streak symptom scores induced by the isolates were statistically significant, but differed only by a maximum of 7% in 1999 and 19% in 2000. Although genotype, isolate, and genotype by isolate effects for maize streak symptom scores were significant (P < 0.01), relative MSV resistance of the genotypes was consistently ranked by all 20 MSV isolates.

scholarly journals Genetic analysis of maize streak virus isolates from Uganda reveals widespread distribution of a recombinant variant

2007 ◽  
Vol 88 (11) ◽  
pp. 3154-3165 ◽  
Author(s):  
Betty E. Owor ◽  
Darren P. Martin ◽  
Dionne N. Shepherd ◽  
Richard Edema ◽  
Adérito L. Monjane ◽  
...  
Keyword(s):  
Maize Streak Virus ◽  
Sub Saharan Africa ◽  
Streak Virus ◽  
Diverse Range ◽  
Genetic Characteristics ◽  
Effective Strategies ◽  
Maize Yields ◽  
Sub Saharan ◽  
Large Survey ◽  
Virus Isolates

Maize streak virus (MSV) contributes significantly to the problem of extremely low African maize yields. Whilst a diverse range of MSV and MSV-like viruses are endemic in sub-Saharan Africa and neighbouring islands, only a single group of maize-adapted variants – MSV subtypes A1–A6 – causes severe enough disease in maize to influence yields substantially. In order to assist in designing effective strategies to control MSV in maize, a large survey covering 155 locations was conducted to assess the diversity, distribution and genetic characteristics of the Ugandan MSV-A population. PCR–restriction fragment-length polymorphism analyses of 391 virus isolates identified 49 genetic variants. Sixty-two full-genome sequences were determined, 52 of which were detectably recombinant. All but two recombinants contained predominantly MSV-A1-like sequences. Of the ten distinct recombination events observed, seven involved inter-MSV-A subtype recombination and three involved intra-MSV-A1 recombination. One of the intra-MSV-A1 recombinants, designated MSV-A1UgIII, accounted for >60 % of all MSV infections sampled throughout Uganda. Although recombination may be an important factor in the emergence of novel geminivirus variants, it is demonstrated that its characteristics in MSV are quite different from those observed in related African cassava-infecting geminivirus species.

Asthma symptom severity and diagnosis in adolescents in sub-Saharan Africa

2021 ◽  
Author(s):  
Victoria Oyenuga ◽  
Gioia Mosler ◽  
Emmanuel Addo-Yobo ◽  
Olayinka Olufunke Adeyeye ◽  
Refiloe Masekela ◽  
...  
Keyword(s):  
Symptom Severity ◽  
Asthma Symptom ◽  
Sub Saharan Africa ◽  
Sub Saharan

Economic freedom, competition and bank stability in Sub-Saharan Africa

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Emmanuel Sarpong-Kumankoma ◽  
Joshua Yindenaba Abor ◽  
Anthony Q. Q. Aboagye ◽  
Mohammed Amidu
Keyword(s):  
Economic Freedom ◽  
Banking Sector ◽  
Generalized Method Of Moments ◽  
Sub Saharan Africa ◽  
Bank Stability ◽  
Content Type ◽  
Show Evidence ◽  
Negative Effect ◽  
Sub Saharan ◽  
The Stability

PurposeThis study aims to analyze the potential implications of economic freedom and competition for bank stability.Design/methodology/approachUsing system generalized method of moments and data from 139 banks across 11 Sub-Saharan African (SSA) countries during the period 2006–2012, this study considers whether the degree of economic freedom affects the relationship between competition and bank stability.FindingsThe results show evidence of the competition-fragility hypothesis in SSA banking, but suggests that beyond a setting threshold, increases in market power may also be damaging to bank stability. Financial freedom has a negative effect on bank stability, suggesting that banks operating in environments with greater financial freedom generally tend to be less stable or more risky. The authors also find evidence of a conditional effect of economic freedom on the competition–stability relationship, implying that bank failure is more likely to occur in countries with greater economic freedom, but with low competition in the banking sector.Practical implicationsThe results suggests to policy makers that a moderate level of competition and economic freedom may be the appropriate policy to ensure the stability of banks.Originality/valueThe study provides insight on the competition–bank stability relationship, by providing new empirical evidence on the effect of economic freedom, which has not been previously considered.

scholarly journals Studies on Maize streak virus and Maize mottle/chlorotic stunt virus in Lagos, Nigeria

Plant Disease ◽  
2006 ◽  
Vol 90 (2) ◽  
pp. 199-202 ◽  
Author(s):  
M. A. Taiwo ◽  
J. d'A. Hughes ◽  
K. E. Oke
Keyword(s):  
Local Government ◽  
Germ Plasm ◽  
Maize Streak Virus ◽  
Dry Season ◽  
Enzyme Linked Immunosorbent Assay ◽  
Streak Virus ◽  
Wet Season ◽  
Visual Examination ◽  
Effective Utilization ◽  
Coated Plate

Despite the development and deployment of maize streak-resistant (SR) germ plasm, virus-induced symptoms are still commonly observed on maize in Lagos, Nigeria. Therefore, surveys were conducted between April 2001 and February 2002 to determine the identity, prevalence, and incidence of maize viruses in 18 local government areas (LGAs) in and around Lagos by visual examination and serodiagnostic screening of symptomatic plants. All 112 fields surveyed during the dry season (September to December) and 18 fields surveyed during the late dry season (December to February) had plants infected by Maize streak virus (MSV), whereas 97.1% of the 170 fields surveyed during the wet season (April to August) had plants infected by MSV. Maize mottle/chlorotic stunt virus (MMCSV) was prevalent in 99.1, 88.9, and 67.4% of the fields surveyed during the dry, late dry, and wet seasons, respectively. The incidence of MSV was higher in 16 of the LGAs. The highest incidence of MSV was 18.9%, whereas that of MMCSV was 7.4%. Serodiagnostic screening of leaf samples showing virus-induced symptoms, using antigen-coated plate enzyme-linked immunosorbent assay, indicated that 1,192/1,475 (80.8%) and 949/1,210 (78.4%) of the samples were positive for MSV and MMCSV, respectively. Vector transmission and host range studies confirmed the identity of the viruses. The results confirm the presence of MSV and MMCSV in Lagos and suggest that the use of MSV-susceptible cultivars is still widespread. Methods of ensuring effective utilization of existing SR germ plasm and controlling maize viruses in general are discussed.

scholarly journals A rep-based hairpin inhibits replication of diverse maize streak virus isolates in a transient assay

2011 ◽  
Vol 92 (10) ◽  
pp. 2458-2465 ◽  
Author(s):  
Betty E. Owor ◽  
Darren P. Martin ◽  
Edward P. Rybicki ◽  
Jennifer A. Thomson ◽  
Marion E. Bezuidenhout ◽  
...  
Keyword(s):  
Virus Replication ◽  
Inverted Repeat ◽  
Virus Genome ◽  
Sub Saharan Africa ◽  
Transcriptional Gene Silencing ◽  
Streak Virus ◽  
Transient Expression Assay ◽  
Specific Pcr ◽  
Post Transcriptional Gene Silencing ◽  
Sub Saharan

Maize streak disease, caused by the A strain of the African endemic geminivirus, maize streak mastrevirus (MSV-A), threatens the food security and livelihoods of subsistence farmers throughout sub-Saharan Africa. Using a well-established transient expression assay, this study investigated the potential of a spliceable-intron hairpin RNA (hpRNA) approach to interfere with MSV replication. Two strategies were explored: (i) an inverted repeat of a 662 bp region of the MSV replication-associated protein gene (rep), which is essential for virus replication and is therefore a good target for post-transcriptional gene silencing; and (ii) an inverted repeat of the viral long intergenic region (LIR), considered for its potential to trigger transcriptional silencing of the viral promoter region. After co-bombardment of cultured maize cells with each construct and an infectious partial dimer of the cognate virus genome (MSV-Kom), followed by viral replicative-form-specific PCR, it was clear that, whilst the hairpin rep construct (pHPrepΔI662) completely inhibited MSV replication, the LIR hairpin construct was ineffective in this regard. In addition, pHPrepΔI662 inhibited or reduced replication of six MSV-A genotypes representing the entire breadth of known MSV-A diversity. Further investigation by real-time PCR revealed that the pHPrepΔI662 inverted repeat was 22-fold more effective at reducing virus replication than a construct containing the sense copy, whilst the antisense copy had no effect on replication when compared with the wild type. This is the first indication that an hpRNA strategy targeting MSV rep has the potential to protect transgenic maize against diverse MSV-A genotypes found throughout sub-Saharan Africa.

scholarly journals The interplay of competition, regulation and stability: the case of Sub-Saharan African commercial banks

2019 ◽  
Vol 14 (1) ◽  
pp. 65-80
Author(s):  
Joseph Olorunfemi Akande ◽  
Farai Kwenda ◽  
Dev Tewari
Keyword(s):  
Regional Integration ◽  
Commercial Banks ◽  
Structural Equation ◽  
Empirical Studies ◽  
Sustainable Growth ◽  
Sub Saharan Africa ◽  
Equation Modelling ◽  
Sub Saharan ◽  
The Stability ◽  
Bank System

Stimulating competition in the bank system without compromising the stability constitutes a major puzzle that bank regulators and practitioners face. Hitherto, empirical studies focusing on Sub-Saharan Africa in addressing these issues for the anticipated regional integration and sustainable growth are rare. This study applied structural equation modelling to simultaneously analyze competition, regulation and stability in a panel of 440 Sub-Saharan African commercial banks over the period from 2006 to 2015. The results provided evidence that competition affects stability via efficiency and that regulation affects stability via competition and efficiency. This study produced critical theoretical and methodological insights with substantial implications for the conduct of bank regulatory policy.

scholarly journals The determinants of Party System Change in Sub-Saharan Africa

2018 ◽  
Vol 8 (2) ◽  
pp. 124-129
Author(s):  
Riccardo Pelizzo
Keyword(s):  
Social Transformation ◽  
Party System ◽  
System Change ◽  
Party Systems ◽  
Party Competition ◽  
Sub Saharan Africa ◽  
Democratic Regimes ◽  
Primary Driver ◽  
Sub Saharan ◽  
The Stability

This article examines what socio-economic factors are conducive to changes in the patterns of inter-party competition in Sub-Saharan Africa (SSA). The literature has in recent years paid considerable attention to measuring party system change, to identifying the consequences of party system instability for the proper functioning of democratic regimes, and to understanding what factors are responsible for the instability of party systems. In contrast to previous studies that view political change in general and party system change more specifically as the result of social transformation, development, modernization and change in the cleavage structure, this paper shows instead that poverty is the primary driver of party system change in the SSA region. In countries with high levels of poverty, political elites do enjoy little to no performance-based legitimacy. The lack of performance-based legitimacy is the reason why voters in such countries are willing to alter their voting habits and parties are unable to preserve their electoral fortunes over time—which is precisely why party systems do change. The literature showed that stable party systems are good for democracy. This paper shows that to enhance the stability of party system in SSA, poverty has to be reduced and possibly eradicated.

scholarly journals Screening of Provitamin-A Maize Inbred Lines for Drought Tolerance Using β-carotene Content: Morphophysiological and Biochemical Traits

Agronomy ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 692 ◽  
Author(s):  
Aleck Kondwakwenda ◽  
Julia Sibiya ◽  
Rebecca Zengeni ◽  
Cousin Musvosvi ◽  
Samson Tesfay
Keyword(s):  
Drought Tolerance ◽  
Vitamin A Deficiency ◽  
Inbred Lines ◽  
Sub Saharan Africa ◽  
Provitamin A ◽  
Biochemical Traits ◽  
Carotene Content ◽  
Maize Productivity ◽  
Sub Saharan ◽  
Β Carotene

Provitamin A maize (Zea mays L.) biofortification is an ideal complementary means of combating vitamin A deficiency (VAD) in sub-Saharan Africa where maize consumption is high coupled by high VAD incidences. However, drought remains a major abiotic constraint to maize productivity in this region. Comprehensive drought screening of initial breeding materials before advancing them is important to achieve genetic gain. In this study, 46 provitamin-A inbred lines were screened for drought tolerance in the greenhouse and field under drought and optimum conditions using β-carotene content (BCC), grain yield (GY), and selected morphophysiological and biochemical traits. The results revealed that BCC, morphophysiological and biochemical traits were effective in discriminating among genotypes. Number of ears per plant (EPP), stomatal conductance (Gs), delayed leaf senescence (SEN), leaf rolling (RL), chlorophyll content (CC) and free proline content (PC) proved to be ideal traits to use when indirectly selecting for GY by virtue of having relative efficiency of indirect selection values that are greater than unity and considerable genetic variances under either or both conditions. The findings of this study form the basis of initial germplasm selection when improving provitamin A maize for drought tolerance.

scholarly journals Stability of the effect of silencing genes involved in the midgut homeostasis on Anopheles arabiensis mosquito reared under different breeding site conditions

2020 ◽  
Author(s):  
Serkadis Debalke ◽  
Tibebu Habtewold ◽  
George K. Christophides ◽  
Luc Duchateau
Keyword(s):  
Gene Silencing ◽  
Anopheles Arabiensis ◽  
Breeding Site ◽  
Larval Habitat ◽  
Sub Saharan Africa ◽  
Female Adult ◽  
Breeding Sites ◽  
First Instar ◽  
Sub Saharan ◽  
The Stability

Abstract Background: Malaria vector mosquitoes acquire midgut microbiota primarily from their habitat. The homeostasis of these microbial communities plays an essential role in the mosquito longevity, the most essential factor in the mosquito vectorial capacity. Our recent study revealed that silencing genes involved in regulation of the midgut homeostasis including FN3D1, FN3D3, and GPRGr9 reduced the survival of female adult Anopheles arabiensis mosquito. In the present study, we investigate the stability of the gene silencing efficiency of mosquitoes reared in three different breeding conditions representing distinct larval habitat types: town brick pits in Jimma, flood pools in the rural land of Asendabo and roadside pools in Wolkite. Methods: First instar larvae of An. arabiensis mosquitoes were reared separately using water collected from the three breeding sites. The resulting adult females were micro-injected with dsRNA targeting the FN3D1 gene (AARA003032) and their survival was monitored. Control mosquitoes were injected with dsRNA Lacz. In addition, the load of midgut microbiota of these mosquitoes was determined using flow cytometry.Result: Survival of naïve adult female mosquitoes differed between the three sites. Mosquitoes reared using water collected from brick pits and flood pools survived longer than mosquitoes reared using water collected from roadside. However, the FN3D1 gene silencing effect on survival did not differ between the three sites. Conclusion: The present study revealed that the efficacy of FN3D1 gene silencing is not affected by variation in the larval habitat. Thus, silencing this gene using genetic engineering approaches can have a large potential for application throughout sub-Saharan Africa.

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