scholarly journals Maize Lethal Necrosis (MLN), an Emerging Threat to Maize-Based Food Security in Sub-Saharan Africa

2015 ◽  
Vol 105 (7) ◽  
pp. 956-965 ◽  
Author(s):  
George Mahuku ◽  
Benham E. Lockhart ◽  
Bramwel Wanjala ◽  
Mark W. Jones ◽  
Janet Njeri Kimunye ◽  
...  
Keyword(s):  
Food Security ◽  
Democratic Republic Of Congo ◽  
Management Strategies ◽  
Sub Saharan Africa ◽  
Eastern Africa ◽  
Smallholder Farming ◽  
Chlorotic Mottle Virus ◽  
Maize Chlorotic Mottle Virus ◽  
Chlorotic Mottle ◽  
Sub Saharan

In sub-Saharan Africa, maize is a staple food and key determinant of food security for smallholder farming communities. Pest and disease outbreaks are key constraints to maize productivity. In September 2011, a serious disease outbreak, later diagnosed as maize lethal necrosis (MLN), was reported on maize in Kenya. The disease has since been confirmed in Rwanda and the Democratic Republic of Congo, and similar symptoms have been reported in Tanzania, Uganda, South Sudan, and Ethiopia. In 2012, yield losses of up to 90% resulted in an estimated grain loss of 126,000 metric tons valued at $52 million in Kenya alone. In eastern Africa, MLN was found to result from coinfection of maize with Maize chlorotic mottle virus (MCMV) and Sugarcane mosaic virus (SCMV), although MCMV alone appears to cause significant crop losses. We summarize here the results of collaborative research undertaken to understand the biology and epidemiology of MLN in East Africa and to develop disease management strategies, including identification of MLN-tolerant maize germplasm. We discuss recent progress, identify major issues requiring further research, and discuss the possible next steps for effective management of MLN.

scholarly journals Response of Assorted Maize Germplasm to the Maize Lethal Necrosis Disease in Kenya

2017 ◽  
Vol 6 (2) ◽  
pp. 65
Author(s):  
Sitta J. ◽  
Nzuve F. M. ◽  
Olubayo F. M. ◽  
Mutinda C. ◽  
Muiru W. M. ◽  
...  
Keyword(s):  
Inbred Lines ◽  
Sub Saharan Africa ◽  
Eastern Africa ◽  
Small Scale ◽  
Maize Productivity ◽  
Maize Genotypes ◽  
Severity Scores ◽  
Chlorotic Mottle Virus ◽  
Maize Chlorotic Mottle Virus ◽  
Chlorotic Mottle

Maize (Zea mays L.) is the most widely grown staple food crop in Sub Saharan Africa (SSA) and occupies more than 33 million hectares each year. The recent outbreak and rapid spread of the Maize Lethal Necrosis (MLN) disease has emerged as a great challenge to maize production, threatening food security for the majority of households in the Eastern Africa region with yield loss estimated to be 50-90%. The disease is a result of synergistic interaction between two viruses, Sugarcane mosaic virus (SCMV) and Maize chlorotic mottle virus (MCMV). The objective of this study was to identify maize genotypes with resistance to MLN. In season one, 73 maize genotypes comprising 25 inbred lines from research institutes, 30 lines from the International Maize and Wheat Improvement Centre (CIMMYT) and 18 farmer varieties were screened for resistance to MLN. In season 2, only 48 genotypes were screened after some of the inbred lines showed complete susceptibility to MLN. These genotypes were grown in three replications in a completely randomized design in polythene bags in the greenhouse at the University of Nairobi. The plants were artificially inoculated using a mixture of SCMV and MCMV. .Weekly MLN disease severity scores using a scale of 1 to 5 (1 = highly resistant and 5 = highly susceptible) and % MLN incidence were recorded and eventually converted into Area under Disease Progress Curve (AUDPC) to give an indication of the disease intensity over time. The plants were allowed to grow to flowering stage to observe the effect of the MLN on the maize productivity. Analysis of Variance revealed wide genetic variation among the genotypes ranging from resistant to highly susceptible. In season 1, three farmer varieties namely MLR2, MLR11 and MLR13 showed resistance to MLN with a mean severity score of 2. In season 2, MLN12, MLN17, MLN18, MLN19, and MLR4 showed low MLN severity ranging from 2-3. The genotypes MLR6, MLR9, MLR16 and MLR18 showed MLN severity of 3 and early maturity traits. This study also validated the presence of MLN resistance among some CIMMYT lines depicted to show resistance in previous studies. These resistant genotypes could serve as donors in the introgression of the resistance into the adapted Kenyan maize backgrounds. This will go a long way in ensuring sustainable maize productivity while improving the livelihoods of the small-scale farmers who form the bulk of the major maize producers in Kenya.

scholarly journals Impact of Fungal Endophyte Colonization of Maize (Zea mays L.) on Induced Resistance to Thrips- and Aphid-Transmitted Viruses

Plants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 416 ◽  
Author(s):  
Simon Kiarie ◽  
Johnson O. Nyasani ◽  
Linnet S. Gohole ◽  
Nguya K. Maniania ◽  
Sevgan Subramanian
Keyword(s):  
Integrated Management ◽  
Management Strategies ◽  
Fungal Endophyte ◽  
Eastern Africa ◽  
Maize Seeds ◽  
Fungal Isolates ◽  
Chlorotic Mottle Virus ◽  
Maize Chlorotic Mottle Virus ◽  
Chlorotic Mottle ◽  
Maize Plants

In eastern Africa, Maize lethal necrosis (MLN) is caused by the co-infection of maize plants with Maize chlorotic mottle virus (MCMV) (Tombusviridae: Machlomovirus) and Sugarcane mosaic virus (SCMV) (Potyviridae: Potyvirus). With the disease being new to Africa, minimal effective management strategies exist against it. This study examined the potential of 10 fungal isolates to colonize maize plants and induce resistance against MCMV and SCMV. Maize seeds were soaked in fungal inoculum, sown and evaluated for endophytic colonization. Fungus-treated plants were challenge-inoculated with SCMV and/or MCMV to assess the effects of fungal isolates on the viruses in terms of incidence, severity and virus titers over time. Isolates of Trichoderma harzianum, Trichoderma atroviride and Hypocrea lixii colonized different plant sections. All plants singly or dually-inoculated with SCMV and MCMV tested positive for the viruses by reverse transcription-polymerase chain reaction (RT-PCR). Maize plants inoculated by T. harzianum and Metarhizium. anisopliae resulted in up to 1.4 and 2.7-fold reduced SCMV severity and titer levels, respectively, over the controls but had no significant effect on MCMV. The results show that both T. harzianum and M. anisopliae are potential candidates for inducing resistance against SCMV and can be used for the integrated management of MLN.

scholarly journals Selecting for Coupling-Phase Recombination Between Potyvirus Resistance and White Endosperm Colour in Maize Preferred by Farmers in Sub-Saharan Africa (SSA)

Afrika Focus ◽  
2019 ◽  
Vol 32 (2) ◽  
pp. 39-48
Author(s):  
Victoria B. Bulegeya ◽  
Mark W. Jones ◽  
Tryphone G. Muhamba ◽  
Biswanath Das ◽  
Peter R. Thomison ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Sub Saharan Africa ◽  
Maize Dwarf Mosaic Virus ◽  
Coupling Phase ◽  
Resistance Selection ◽  
Chlorotic Mottle Virus ◽  
Maize Chlorotic Mottle Virus ◽  
Chlorotic Mottle ◽  
Sub Saharan ◽  
Combined Infection

Maize lethal necrosis (MLN) disease caused by a combined infection of Maize chlorotic mottle virus (MCMV) and any cereal infecting potyvirus is a threat to food security in Sub-Saharan Africa (SSA). Resistance to potyvirus has been extensively studied and Mdm1 gene for potyvirus resistance on chromosome 6 of maize is linked to Y1 gene for maize endosperm colour. This study is aimed at selecting for coupling-phase recombination of potyvirus resistance and white endosperm colour. White susceptible maize lines CML333 and CML277 were crossed with a yellow resistant line, Pa405, to produce F1 and F2 progenies. Progenies were screened using molecular markers to recover 22 white endosperm recombinants. 22 selections were advanced to F3 recombinant families, and 10 were assayed for their responses to Maize dwarf mosaic virus (MDMV) and Sugarcane mosaic virus (SCMV). Four families segregated for SCMV resistance, selection of homozygous recombinants within these families will provide lines appropriate for improving lines with resistance to SCMV and MLN resistance in SSA.

scholarly journals A first global phylogeny ofMaize chlorotic mottle virus

2017 ◽  
Author(s):  
Luke A Braidwood ◽  
Diego F Quito-Avila ◽  
Darlene Cabanas ◽  
Alberto Bressan ◽  
Anne Wangai ◽  
...  
Keyword(s):  
East Africa ◽  
Total Yield ◽  
Sub Saharan Africa ◽  
Mottle Virus ◽  
Adjusted Rand Index ◽  
Maize Production ◽  
Chlorotic Mottle Virus ◽  
Maize Chlorotic Mottle Virus ◽  
Chlorotic Mottle ◽  
Sub Saharan

ABSTRACTMaize chlorotic mottle virushas been rapidly spreading around the globe over the past decade. The interactions ofMaize chlorotic mottle viruswith potyviridae viruses causes an aggressive synergistic viral condition - maize lethal necrosis, which can cause total yield loss. Maize production in sub-Saharan Africa, where it is the most important cereal, is threatened by the arrival of maize lethal necrosis. We obtainedMaize chlorotic mottle virusgenome sequences from across East Africa and for the first time from Ecuador and Hawaii, and constructed a phylogeny which highlights the similarity of Chinese to African isolates, and Ecuadorian to Hawaiian isolates. We used a measure of clustering, the adjusted Rand index, to extract region-specific SNPs and coding variation that can be used for diagnostics. The population genetics analysis we performed shows that the majority of sequence diversity is partitioned between populations, with diversity extremely low within China and East Africa.

scholarly journals Modeling Virus Coinfection to Inform Management of Maize Lethal Necrosis in Kenya

2017 ◽  
Vol 107 (10) ◽  
pp. 1095-1108 ◽  
Author(s):  
Frank M. Hilker ◽  
Linda J. S. Allen ◽  
Vrushali A. Bokil ◽  
Cheryl J. Briggs ◽  
Zhilan Feng ◽  
...  
Keyword(s):  
Cropping Systems ◽  
Good Control ◽  
Sub Saharan Africa ◽  
Modeling Framework ◽  
Growing Seasons ◽  
Chlorotic Mottle Virus ◽  
Maize Chlorotic Mottle Virus ◽  
Chlorotic Mottle ◽  
Sources Of Infection ◽  
Sub Saharan

Maize lethal necrosis (MLN) has emerged as a serious threat to food security in sub-Saharan Africa. MLN is caused by coinfection with two viruses, Maize chlorotic mottle virus and a potyvirus, often Sugarcane mosaic virus. To better understand the dynamics of MLN and to provide insight into disease management, we modeled the spread of the viruses causing MLN within and between growing seasons. The model allows for transmission via vectors, soil, and seed, as well as exogenous sources of infection. Following model parameterization, we predict how management affects disease prevalence and crop performance over multiple seasons. Resource-rich farmers with large holdings can achieve good control by combining clean seed and insect control. However, crop rotation is often required to effect full control. Resource-poor farmers with smaller holdings must rely on rotation and roguing, and achieve more limited control. For both types of farmer, unless management is synchronized over large areas, exogenous sources of infection can thwart control. As well as providing practical guidance, our modeling framework is potentially informative for other cropping systems in which coinfection has devastating effects. Our work also emphasizes how mathematical modeling can inform management of an emerging disease even when epidemiological information remains scanty.[Formula: see text] Copyright © 2017 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

scholarly journals Selecting for Coupling Phase Recombination between Potyvirus Resitance and White Endosperm Colour in Maize Preferred by Farmers in Sub-Saharan Africa (SSA)

Afrika Focus ◽  
2019 ◽  
Vol 32 (2) ◽  
Author(s):  
Victoria B. Bulegeya ◽  
Mark W. Jones ◽  
Tryphone G. Muhamba ◽  
Biswanath Das ◽  
Peter R. Thomison ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Genetic Recombination ◽  
Sub Saharan Africa ◽  
Maize Dwarf Mosaic Virus ◽  
Coupling Phase ◽  
Chlorotic Mottle Virus ◽  
Maize Chlorotic Mottle Virus ◽  
Chlorotic Mottle ◽  
Sub Saharan ◽  
Combined Infection

Maize lethal necrosis (MLN) disease caused by a combined infection of Maize chlorotic mottle virus (MCMV) and any cereal infecting potyvirus is a threat to food security in Sub-Saharan Africa (SSA). Resistance to potyvirus has been extensively studied and Mdm1 gene for potyvirus resistance on chromosome 6 of maize is linked to Y1 gene for maize endosperm colour. This study is aimed at se- lecting for coupling-phase recombination of potyvirus resistance and white endosperm colour. White susceptible maize lines CML333 and CML277 were crossed with a yellow resistant line, Pa405, to produce F1 and F2 progenies. Progenies were screened using molecular markers to recover 22 white endosperm recombinants. 22 selections were advanced to F3 recombinant families, and 10 were as- sayed for their responses to Maize dwarf mosaic virus (MDMV) and Sugarcane mosaic virus (SCMV). Four families segregated for SCMV resistance, selection of homozygous recombinants within these families will provide lines appropriate for improving lines with resistance to SCMV and MLN resistance in SSA. KEY WORDS: MAIZE LETHAL NECROSIS (MLN), WHITE MAIZE, POTYVIRUS RESISTANCE, GENETIC RECOMBINATION, SUB-SAHARAN AFRICA.

scholarly journals Characterising maize viruses associated with maize lethal necrosis symptoms in sub Saharan Africa

2017 ◽  
Author(s):  
I.P. Adams ◽  
L.A. Braidwood ◽  
F. Stomeo ◽  
N. Phiri ◽  
B. Uwumukiza ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Sub Saharan Africa ◽  
Yellow Mosaic Virus ◽  
Field Variation ◽  
Emerging Viruses ◽  
Negative Results ◽  
Chlorotic Mottle Virus ◽  
Maize Chlorotic Mottle Virus ◽  
Chlorotic Mottle ◽  
Sub Saharan

AbstractMaize lethal necrosis disease (MLN) is an emerging disease in East Africa caused by the introduction of Maize chlorotic mottle virus (MCMV). Recent activity seeking to limit spread of the disease is reliant on effective diagnostics. Traditional diagnostics applied on samples with typical field symptoms of MLN have often given negative results using ELISA or PCR for MCMV and Sugarcane mosaic virus (SCMV). Samples collected in the field with typical MLN symptoms were examined using next generation sequencing (NGS). SCMV was found to be more prevalent than suggested by targeted diagnostics. Additionally, the panel of samples were found to be infected with a range of other viruses, seven of which are described here for the first time. Although not previously identified in the region, Maize yellow mosaic virus (MYMV) was the most prevalent virus after MCMV. The development of targeted diagnostics for emerging viruses is complicated when the extent of field variation is unknown, something that can be negated by using NGS methods. As a result we explored MinION technology which may be more readily deployable in resource poor settings. The results show that this sequencer can diagnose known viruses and future iterations have the potential to identify novel viruses.

scholarly journals Precision Agriculture for Resource Use Efficiency in Smallholder Farming Systems in Sub-Saharan Africa: A Systematic Review

2021 ◽  
Vol 13 (3) ◽  
pp. 1158
Author(s):  
Cecilia M. Onyango ◽  
Justine M. Nyaga ◽  
Johanna Wetterlind ◽  
Mats Söderström ◽  
Kristin Piikki
Keyword(s):  
Resource Use ◽  
Precision Agriculture ◽  
Large Scale ◽  
English Language ◽  
Management Practices ◽  
Smallholder Farmers ◽  
Management Strategies ◽  
Sub Saharan Africa ◽  
Smallholder Farming ◽  
Sub Saharan

Opportunities exist for adoption of precision agriculture technologies in all parts of the world. The form of precision agriculture may vary from region to region depending on technologies available, knowledge levels and mindsets. The current review examined research articles in the English language on precision agriculture practices for increased productivity among smallholder farmers in Sub-Saharan Africa. A total of 7715 articles were retrieved and after screening 128 were reviewed. The results indicate that a number of precision agriculture technologies have been tested under SSA conditions and show promising results. The most promising precision agriculture technologies identified were the use of soil and plant sensors for nutrient and water management, as well as use of satellite imagery, GIS and crop-soil simulation models for site-specific management. These technologies have been shown to be crucial in attainment of appropriate management strategies in terms of efficiency and effectiveness of resource use in SSA. These technologies are important in supporting sustainable agricultural development. Most of these technologies are, however, at the experimental stage, with only South Africa having applied them mainly in large-scale commercial farms. It is concluded that increased precision in input and management practices among SSA smallholder farmers can significantly improve productivity even without extra use of inputs.

scholarly journals Modelling potential range expansion of an underutilised food security crop in Sub-Saharan Africa

2021 ◽  
Author(s):  
Olef Koch ◽  
Wendawek Abebe Mengesha ◽  
Samuel Pironon ◽  
Pagella Tim ◽  
Ian Ondo ◽  
...  
Keyword(s):  
Food Security ◽  
Range Expansion ◽  
Lake Victoria ◽  
Sub Saharan Africa ◽  
Eastern Africa ◽  
Small Scale ◽  
Potential Range ◽  
Niche Modelling ◽  
Ethical Implications ◽  
Sub Saharan

Abstract Despite substantial growth in global agricultural production, food and nutritional insecurity is rising in Sub-Saharan Africa. Identification of underutilised indigenous crops with useful food security traits may provide part of the solution. Enset (Ensete ventricosum) is a perennial banana relative with cultivation restricted to southwestern Ethiopia, where high productivity and harvest flexibility enables it to provide a starch staple for ~20 million people. An extensive wild distribution suggests that a much larger region may be climatically suitable for cultivation. Here we use ensemble ecological niche modelling to predict the potential range for enset cultivation within southern and eastern Africa. We find contemporary bioclimatic suitability for a 12-fold range expansion, equating to 21.9% of crop land and 28.4% of the population in the region. Integration of crop wild relative diversity, which has broader climate tolerance, could enable a 19-fold expansion, particularly to dryer and warmer regions. Whilst climate change may cause a 37% – 52% reduction in potential range by 2070, large centres of suitability remain in the Ethiopian Highlands, Lake Victoria region and the Drakensberg Range. We combine our bioclimatic assessment with socioeconomic data to identify priority areas with high population density, seasonal food deficits and predominantly small-scale subsistence agriculture, where integrating enset may be particularly feasible and deliver climate resilience. When incorporating the genetic potential of wild populations, enset cultivation might prove feasible for an additional 87.2 - 111.5 million people, 27.7 – 33 million of which are in Ethiopia outside of enset’s current cultivation range. Finally, we consider explanations why enset cultivation has not expanded historically, and ethical implications of expanding previously underutilised species.

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