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

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.

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

Phytopathology ◽

10.1094/phyto-12-14-0367-fi ◽

2015 ◽

Vol 105 (7) ◽

pp. 956-965 ◽

Cited By ~ 100

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.

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Response of Selected Maize Inbred Germplasm to Maize Lethal Necrosis Disease and Its Causative Viruses (Sugarcane Mosaic Virus and Maize Chlorotic Mottle Virus) in Kenya

The Open Agriculture Journal ◽

10.2174/1874331501812010215 ◽

2018 ◽

Vol 12 (1) ◽

pp. 215-226 ◽

Cited By ~ 4

Author(s):

James Karanja ◽

John Derera ◽

Augustine Gubba ◽

Stephen Mugo ◽

Ann Wangai

Keyword(s):

Food Security ◽

Mosaic Virus ◽

Smallholder Farmers ◽

Inbred Lines ◽

Sugarcane Mosaic Virus ◽

Mottle Virus ◽

Maize Productivity ◽

Chlorotic Mottle Virus ◽

Maize Chlorotic Mottle Virus ◽

Chlorotic Mottle

Background: Maize lethal necrosis (MLN) disease continues to reduce the productivity of maize drastically threatening food security in the affected regions. It continues to cause yield loss of 30–100 percent in farmers’ fields, depending on the time of infestation which is valued at $198 million in Kenya. This has not only threatened regional trade, but also seed industry. It has been reported in the major maize belts of Uasin Gishu, Trans-Nzoia, Bomet, Narok and Nandi Counties. MLN is caused by the synergistic interaction between Sugarcane Mosaic Virus (SCMV) and Maize Chlorotic Mottle Virus (MCMV). The disease has then spread to other Eastern and Central African countries with devastating food security and economic consequences. Objectives: This study highlights result after screening selected maize inbred lines for resistance to MLN, SCMV and MCMV in identifying promising lines for integration into the breeding program for MLN resistance. Methods: Sixty-five (65) maize genotypes were artificially inoculated using virus strains collected from Bomet County in Kenya at 3-4 leaf stage. Data on disease severity and incidence, AUDPC and flowering were recorded. Results: From the result, the inbred lines had significant differences for SCMV, MCMV and MLN reactions. Based on Area Under Disease Progress Curve (AUDPC) score and ELISA analysis, genotypes MLN001 and MLN006 have the lowest score of 270, whereas OH28 had a maximum at 1259 under MCMV. Genotypes MLN042 and MLN041 were identified as the most promising sources of resistant against SCMV. However, no genotype was identified to have acceptable levels of tolerance to MLN, but MLN001 and MLN013 were identified as the best performers under MLN. This study also validated the presence of MLN tolerance in MLN013 (CKDHL120312) and MLN001 (CKDHL120918) as earlier reported by CIMMYT. These tolerant genotypes are now serving as donors in the introgression of the tolerance into the Kenyan adapted maize backgrounds and development of improved MLN tolerant varieties. This will go a long way in restoring and ensuring sustainable maize productivity in improving the livelihoods of the smallholder farmers who form 75% of the major maize producers in Kenya. Conclusion: The identified inbred lines would be recommended for use in varietal development, MLN management and to enhance maize productivity, in the MLN endemic regions and further research in understanding the mode of gene action for MLN tolerance.

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

Plants ◽

10.3390/plants9040416 ◽

2020 ◽

Vol 9 (4) ◽

pp. 416 ◽

Cited By ~ 1

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.

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A Recently Discovered Maize Polerovirus Causes Leaf Reddening Symptoms in Several Maize Genotypes and is Transmitted by Both the Corn Leaf Aphid (Rhopalosiphum maidis) and the Bird Cherry-Oat Aphid (Rhopalosiphum padi)

Plant Disease ◽

10.1094/pdis-09-19-2054-sc ◽

2020 ◽

Vol 104 (6) ◽

pp. 1589-1592

Author(s):

Lucy R. Stewart ◽

Jane Todd ◽

Kristen Willie ◽

Deogracious Massawe ◽

Nitika Khatri

Keyword(s):

Infectious Clone ◽

Rhopalosiphum Padi ◽

Yellow Mosaic Virus ◽

Insect Vector ◽

Rhopalosiphum Maidis ◽

Maize Genotypes ◽

Chlorotic Mottle Virus ◽

Maize Chlorotic Mottle Virus ◽

Chlorotic Mottle ◽

Yellow Dwarf Virus

A maize-infecting polerovirus variously named maize yellow dwarf virus RMV2 (MYDV-RMV2) and maize yellow mosaic virus (MaYMV) has been discovered and previously described in East Africa, Asia, and South America. It was identified in virus surveys in these locations instigated by outbreaks of maize lethal necrosis (MLN), known to be caused by coinfections of unrelated maize chlorotic mottle virus (MCMV) and any of several maize-infecting potyviruses, and was often found in coinfections with MLN viruses. Although sequenced in many locations globally and named for symptoms of related or coinfecting viruses, and with an infectious clone reported that experimentally infects Nicotiana benthamiana, rudimentary biological characterization of MaYMV in maize, including insect vector(s) and symptoms in single infections, has not been reported until now. We report isolation from other viruses and leaf tip reddening symptoms in several maize genotypes, along with transmission by two aphids, Rhopalosiphum padi and Rhopalosiphum maidis. This is important information distinguishing this virus and demonstrating that in single infections it causes symptoms distinct from those of potyviruses or MCMV in maize, and identification of vectors provides an important framework for determination of potential disease impact and management.

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

Afrika Focus ◽

10.1163/2031356x-03202004 ◽

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.

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Diverse Chromosomal Locations of Quantitative Trait Loci for Tolerance to Maize chlorotic mottle virus in Five Maize Populations

Phytopathology ◽

10.1094/phyto-09-17-0321-r ◽

2018 ◽

Vol 108 (6) ◽

pp. 748-758 ◽

Cited By ~ 11

Author(s):

Mark W. Jones ◽

Bryan W. Penning ◽

Tiffany M. Jamann ◽

Jeff C. Glaubitz ◽

Cinta Romay ◽

...

Keyword(s):

Quantitative Trait Loci ◽

Quantitative Trait ◽

Leaf Tissue ◽

Inbred Lines ◽

Mottle Virus ◽

Maize Populations ◽

Chlorotic Mottle Virus ◽

Maize Chlorotic Mottle Virus ◽

Chlorotic Mottle ◽

Trait Loci

The recent rapid emergence of maize lethal necrosis (MLN), caused by coinfection of maize with Maize chlorotic mottle virus (MCMV) and a second virus usually from the family Potyviridae, is causing extensive losses for farmers in East Africa, Southeast Asia, and South America. Although the genetic basis of resistance to potyviruses is well understood in maize, little was known about resistance to MCMV. The responses of five maize inbred lines (KS23-5, KS23-6, N211, DR, and Oh1VI) to inoculation with MCMV, Sugarcane mosaic virus, and MLN were characterized. All five lines developed fewer symptoms than susceptible controls after inoculation with MCMV; however, the virus was detected in systemic leaf tissue from each of the lines similarly to susceptible controls, indicating that the lines were tolerant of MCMV rather than resistant to it. Except for KS23-5, the inbred lines also developed fewer symptoms after inoculation with MLN than susceptible controls. To identify genetic loci associated with MCMV tolerance, large F2 or recombinant inbred populations were evaluated for their phenotypic responses to MCMV, and the most resistant and susceptible plants were genotyped by sequencing. One to four quantitative trait loci (QTL) were identified in each tolerant population using recombination frequency and positional mapping strategies. In contrast to previous studies of virus resistance in maize, the chromosomal positions and genetic character of the QTL were unique to each population. The results suggest that different, genotype-specific mechanisms are associated with MCMV tolerance in maize. These results will allow for the development of markers for marker-assisted selection of MCMV- and MLN-tolerant maize hybrids for disease control.

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A first global phylogeny ofMaize chlorotic mottle virus

10.1101/209940 ◽

2017 ◽

Cited By ~ 1

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.

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Genetic diversity of maize accessions for maizelethal necrosis disease resistance

Indian Journal of Agricultural Research ◽

10.18805/ijare.v51i1.7056 ◽

2016 ◽

Vol 51 (1) ◽

Author(s):

Patrick Ndakidemi ◽

Mujuni Kabululu Sospeter ◽

Joseph Ndunguru ◽

Tileye Feyissa

Keyword(s):

Genetic Diversity ◽

Disease Resistance ◽

Eastern Africa ◽

Maize Production ◽

Chlorotic Mottle Virus ◽

Maize Chlorotic Mottle Virus ◽

Chlorotic Mottle ◽

Maize Varieties ◽

The World ◽

Plant Characteristics

Maize is among the most preferred crop in Tanzania and other parts of the world. However, its production has been facing a number of challenges. Maize Lethal Necrosis Disease (MLND) is a new challenge in Eastern Africa. The control of MLND is said to be complicated as it is caused by a combination of more than one virus viz. Maize Chlorotic Mottle Virus (MCMV) and Sugarcane Mosaic Virus (SCMV). Stakeholders agree that the priority is to identify MLND resistant maize varieties. Genetic diversity provides the source of traits required against maize production challenges such as MLND. The study of genetic diversity in maize accessions often involves characterizing morphological plant characteristics as well as molecular marker techniques to study variation at DNA level. This review explores different literatures that address the importance of genetic diversity and the possibility of generating information towards obtaining potential materials against maize challenges and MLND in particular.

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

Phytopathology ◽

10.1094/phyto-03-17-0080-fi ◽

2017 ◽

Vol 107 (10) ◽

pp. 1095-1108 ◽

Cited By ~ 19

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 .

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

Afrika Focus ◽

10.21825/af.v32i2.15759 ◽

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.

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