Modelling and manipulation of plant-aphid interactions: A new avenue for sustainable disease management of an important crop in Africa
Lead Research Organisation:
University of Cambridge
Department Name: Plant Sciences
Abstract
In Eastern and Central Africa beans are a vital crop because they enrich the soil with fixed nitrogen (an indispensable natural fertilizer), which in turn supports the cultivation of other important crops such as corn (maize) and cassava. Beans are an essential part of the regional diet because they are rich in protein and crucially important micronutrients like iron and zinc. Since beans are predominantly grown and traded by women, this crop provides additional direct economic benefits to women and their children. Unfortunately, a number of viruses attack bean plants, causing severe crop losses from disease. Although there are a few bean varieties with resistance to one of these viruses (called bean common mosaic virus), a closely related virus that occurs widely in, and is indigenous to, Africa (bean common necrotic mosaic virus) causes plants of these 'resistant' lines to die. Thus, it is important to develop new strategies to defend this vital crop.
Our approach is to attack the insects (aphids) that transmit these viruses from plant to plant. We have found that aphid-plant interactions are controlled in large part by the plant's 'small RNA pathways'. Small RNA pathways are a recently discovered regulatory system used by plants and many other organisms to control the expression of their own genes as well as to fight off disease. The discovery of small RNA pathways has revolutionized biology and medicine. In plants, small RNA pathways control, among other things, the production of natural signal chemicals that attract or repel insect pests, including aphids. Intriguingly, viruses produce factors called 'silencing suppressors' that modify small RNA pathways. We have found that silencing suppressors affect the interactions of virus-infected plants with aphids in a way that is likely to enhance the rate at which these insects acquire viruses and transport them to other plants. We have assembled a team of scientists based in Uganda, Kenya and at two centres in the UK to translate these findings from the laboratory to the field and exploit them for protection of beans. However, aphids and the viruses they transmit are problems for all major crops and the work will yield vital data for the wider field of crop protection.
Our multinational team will collaborate to:
A. Identify potential factors involved in mediating plant-aphid communication in plants: small RNAs, the genes they control, and the chemical signals whose production they regulate.
B. Use the modelling methods provided by the discipline of mathematical epidemiology to help us design experiments (under lab and later field conditions) to predict how altering the attractiveness of plants (whether engendered by changes in the plant or deployment of signal chemicals as traps or decoys) could be used to help minimize or prevent the transmission of viruses.
C. Utilize the work from 1 and 2 to design experiments to test the effects on virus transmission of modifying plant responses to aphids or utilization of purified signal chemicals to trap or deter aphids under controlled and simulated field conditions.
D. To achieve impact by disseminating information gained from our work to African crop scientists, growers and consumers through the Pan-Africa Bean Research Alliance, a network of the national bean research programmes of 28 African nations.
Our approach is to attack the insects (aphids) that transmit these viruses from plant to plant. We have found that aphid-plant interactions are controlled in large part by the plant's 'small RNA pathways'. Small RNA pathways are a recently discovered regulatory system used by plants and many other organisms to control the expression of their own genes as well as to fight off disease. The discovery of small RNA pathways has revolutionized biology and medicine. In plants, small RNA pathways control, among other things, the production of natural signal chemicals that attract or repel insect pests, including aphids. Intriguingly, viruses produce factors called 'silencing suppressors' that modify small RNA pathways. We have found that silencing suppressors affect the interactions of virus-infected plants with aphids in a way that is likely to enhance the rate at which these insects acquire viruses and transport them to other plants. We have assembled a team of scientists based in Uganda, Kenya and at two centres in the UK to translate these findings from the laboratory to the field and exploit them for protection of beans. However, aphids and the viruses they transmit are problems for all major crops and the work will yield vital data for the wider field of crop protection.
Our multinational team will collaborate to:
A. Identify potential factors involved in mediating plant-aphid communication in plants: small RNAs, the genes they control, and the chemical signals whose production they regulate.
B. Use the modelling methods provided by the discipline of mathematical epidemiology to help us design experiments (under lab and later field conditions) to predict how altering the attractiveness of plants (whether engendered by changes in the plant or deployment of signal chemicals as traps or decoys) could be used to help minimize or prevent the transmission of viruses.
C. Utilize the work from 1 and 2 to design experiments to test the effects on virus transmission of modifying plant responses to aphids or utilization of purified signal chemicals to trap or deter aphids under controlled and simulated field conditions.
D. To achieve impact by disseminating information gained from our work to African crop scientists, growers and consumers through the Pan-Africa Bean Research Alliance, a network of the national bean research programmes of 28 African nations.
Technical Summary
Our overall objective is to assess potential risks/benefits for disease management (using epidemiological modelling with experimental validation) from identifying and adapting the knowledge/tools (including gene sequences/semiochemicals/epidemiological models) from studying viral suppressor of RNA silencing-mediated effects on aphid-plant relations to develop 'push-pull'-type systems to protect bean. However, aphids are important pests and disease vectors affecting all major crops, meaning our results will have wide applicability. Our collaboration will translate work from model systems (Arabidopsis and tobacco) to a vital crop (bean) with uniquely African viral disease problems (with emphasis the combined effects of bean common mosaic virus and bean common necrotic mosaic). Key objectives/activities are listed with lead researcher(s) and time-scales indicated in parentheses.
1. Epidemiological modelling (Yrs 1-4, CAG, Cam)
2. Validation and exploration of modelling predictions in controlled conditions (Yrs 1-4, Cam)
3. Field surveys and data collection in Uganda (Yr. 1) and experiments utilizing data from 1 and 2, and field samples (Yrs. 2-4)(MA, CIAT)
4. Analyzing the effects of silencing suppressors on bean mRNA and small RNA profiles (Yrs 2-4) (JH, AD, BecA; DB, Cam)
5. Metabolite analyses to identify semiochemicals produced by bean that influence plant-aphid interactions (Yrs 2-4, Rothamsted)
6. Initiating pathways to impact activities via the Pan-Africa Bean Research Alliance, a network of the national bean research programmes of 28 African nations (Yr3/4; Lead: MA, CIAT).
1. Epidemiological modelling (Yrs 1-4, CAG, Cam)
2. Validation and exploration of modelling predictions in controlled conditions (Yrs 1-4, Cam)
3. Field surveys and data collection in Uganda (Yr. 1) and experiments utilizing data from 1 and 2, and field samples (Yrs. 2-4)(MA, CIAT)
4. Analyzing the effects of silencing suppressors on bean mRNA and small RNA profiles (Yrs 2-4) (JH, AD, BecA; DB, Cam)
5. Metabolite analyses to identify semiochemicals produced by bean that influence plant-aphid interactions (Yrs 2-4, Rothamsted)
6. Initiating pathways to impact activities via the Pan-Africa Bean Research Alliance, a network of the national bean research programmes of 28 African nations (Yr3/4; Lead: MA, CIAT).
Planned Impact
The project focuses on development of solutions to problems caused by viruses and the aphids that transmit them in bean. Bean (Phaseolus vulgaris) is an important crop because: it is a primary source of protein and trace elements in the East and Central African diet; it is a vital intercrop required for high yields and biotic and abiotic stress resistance in other crops including maize and cassava, and because it is of particular economic as well as nutritive value to women and children in the region. But the project will generate outputs (epidemiological models, genes, and gene sequences, and semiochemicals) that will be useful for addressing aphid and virus problems in any crop in any region, especially in the face of the treat to food security posed by spread of insecticide resistance, and the emergence of novel aphid-vectored diseases. Impact will be achieved through four interrelated activities.
1. Impact through Capacity Building The project enables BecA and ECABREN to expand research beyond their respective ILRI and CIAT core-funded activities but in line with priorities developed in consultation with African national partners both in the public and private sectors (see Letters of Support from NARO, Uganda and FICA Seeds Ltd., Uganda). Impact will be achieved through training of personnel at all levels especially the training of a PhD student and the Kenya and Uganda-based PDRAs in state-of-the-art methodologies. The project will also enhance the ability of UK partners to contribute to future North-South collaborative projects.
2. Impact through Publication and Dissemination of Scientific Results including novel epidemiological models, transcriptomic and metabolomic datasets and semiochemicals, peer-reviewed papers and conference presentations.
3. Achieving Impact with Growers, National Research Organizations (NAROs), and Industry in the African arena utilizing the Pan Africa Bean Research Alliance's excellent network to feed information/tools to end-users (primarily small-holder growers including a high proportion of women). PABRA has a strong track record for participatory monitoring and evaluation in assessment of impact using results-based indicators to track project achievements and progress towards positive economic and social goals. We will closely with Dr Robin Buruchara, PABRA co-ordinator (based at CIAT Kampala) on this phase.
4. Achieving Impact: Public communication and engagement in the UK by engagement with the public through existing arrangements at Cambridge and Rothamsted Research.
1. Impact through Capacity Building The project enables BecA and ECABREN to expand research beyond their respective ILRI and CIAT core-funded activities but in line with priorities developed in consultation with African national partners both in the public and private sectors (see Letters of Support from NARO, Uganda and FICA Seeds Ltd., Uganda). Impact will be achieved through training of personnel at all levels especially the training of a PhD student and the Kenya and Uganda-based PDRAs in state-of-the-art methodologies. The project will also enhance the ability of UK partners to contribute to future North-South collaborative projects.
2. Impact through Publication and Dissemination of Scientific Results including novel epidemiological models, transcriptomic and metabolomic datasets and semiochemicals, peer-reviewed papers and conference presentations.
3. Achieving Impact with Growers, National Research Organizations (NAROs), and Industry in the African arena utilizing the Pan Africa Bean Research Alliance's excellent network to feed information/tools to end-users (primarily small-holder growers including a high proportion of women). PABRA has a strong track record for participatory monitoring and evaluation in assessment of impact using results-based indicators to track project achievements and progress towards positive economic and social goals. We will closely with Dr Robin Buruchara, PABRA co-ordinator (based at CIAT Kampala) on this phase.
4. Achieving Impact: Public communication and engagement in the UK by engagement with the public through existing arrangements at Cambridge and Rothamsted Research.
Publications
Palukaitis P
(2013)
The Rumsfeld paradox: some of the things we know that we don't know about plant virus infection.
in Current opinion in plant biology
Xu A
(2013)
Self-interaction of the cucumber mosaic virus 2b protein plays a vital role in the suppression of RNA silencing and the induction of viral symptoms.
in Molecular plant pathology
Ling R
(2013)
An essential fifth coding ORF in the sobemoviruses.
in Virology
Hunter L
(2013)
Regulation of RNA-Dependent RNA Polymerase 1 and Isochorismate Synthase Gene Expression in Arabidopsis
in PLoS ONE
Westwood JH
(2013)
A viral RNA silencing suppressor interferes with abscisic acid-mediated signalling and induces drought tolerance in Arabidopsis thaliana.
in Molecular plant pathology
Westwood JH
(2013)
A trio of viral proteins tunes aphid-plant interactions in Arabidopsis thaliana.
in PloS one
Zhou T
(2014)
Domains of the cucumber mosaic virus 2b silencing suppressor protein affecting inhibition of salicylic acid-induced resistance and priming of salicylic acid accumulation during infection.
in The Journal of general virology
Westwood JH
(2014)
Interference with jasmonic acid-regulated gene expression is a general property of viral suppressors of RNA silencing but only partly explains virus-induced changes in plant-aphid interactions.
in The Journal of general virology
McDowell JM
(2014)
Focus on translational research.
in Molecular plant-microbe interactions : MPMI
Du Z
(2014)
Using a viral vector to reveal the role of microRNA159 in disease symptom induction by a severe strain of Cucumber mosaic virus.
in Plant physiology
Olspert A
(2015)
Transcriptional slippage in the positive-sense RNA virus family Potyviridae.
in EMBO reports
Liao Q
(2015)
An improved cucumber mosaic virus-based vector for efficient decoying of plant microRNAs.
in Scientific reports
Worrall EA
(2015)
Bean Common Mosaic Virus and Bean Common Mosaic Necrosis Virus: Relationships, Biology, and Prospects for Control.
in Advances in virus research
Olspert A
(2016)
Mutational analysis of the Potyviridae transcriptional slippage site utilized for expression of the P3N-PIPO and P1N-PISPO proteins.
in Nucleic acids research
Hunter LJ
(2016)
RNA-dependent RNA polymerase 1 in potato (Solanum tuberosum) and its relationship to other plant RNA-dependent RNA polymerases.
in Scientific reports
Groen SC
(2016)
Virus Infection of Plants Alters Pollinator Preference: A Payback for Susceptible Hosts?
in PLoS pathogens
Groen SC
(2017)
Engineering resistance to virus transmission.
in Current opinion in virology
Macaulay KM
(2017)
The biochemical properties of the two Arabidopsis thaliana isochorismate synthases.
in The Biochemical journal
Tungadi T
(2017)
Cucumber mosaic virus and its 2b protein alter emission of host volatile organic compounds but not aphid vector settling in tobacco.
in Virology journal
Palukaitis P
(2017)
Manipulation of induced resistance to viruses.
in Current opinion in virology
Carr JP
(2018)
Viral Manipulation of Plant Stress Responses and Host Interactions With Insects.
in Advances in virus research
Mutuku JM
(2018)
Metagenomic Analysis of Plant Virus Occurrence in Common Bean (Phaseolus vulgaris) in Central Kenya.
in Frontiers in microbiology
Carr JP
(2019)
Plant defense signals: Players and pawns in plant-virus-vector interactions.
in Plant science : an international journal of experimental plant biology
Wamonje FO
(2019)
Different Plant Viruses Induce Changes in Feeding Behavior of Specialist and Generalist Aphids on Common Bean That Are Likely to Enhance Virus Transmission.
in Frontiers in plant science
Worrall EA
(2019)
Exogenous Application of RNAi-Inducing Double-Stranded RNA Inhibits Aphid-Mediated Transmission of a Plant Virus.
in Frontiers in plant science
Rhee SJ
(2020)
Effects of the cucumber mosaic virus 2a protein on aphid-plant interactions in Arabidopsis thaliana.
in Molecular plant pathology
Wamonje FO
(2020)
Three Aphid-Transmitted Viruses Encourage Vector Migration From Infected Common Bean (Phaseolus vulgaris) Plants Through a Combination of Volatile and Surface Cues.
in Frontiers in plant science
Carr JP
(2020)
Modelling and manipulation of aphid-mediated spread of non-persistently transmitted viruses.
in Virus research
Fening KO
(2020)
First Report and Distribution of the Indian Mustard Aphid, Lipaphis erysimi pseudobrassicae (Hemiptera: Aphididae) on Cabbage (Brassica oleracea var capitata) in Ghana.
in Journal of economic entomology
Murphy AM
(2020)
An update on salicylic acid biosynthesis, its induction and potential exploitation by plant viruses.
in Current opinion in virology
Tungadi T
(2020)
Cucumber mosaic virus 2b proteins inhibit virus-induced aphid resistance in tobacco.
in Molecular plant pathology
Mhlanga N
(2021)
An Innate Preference of Bumblebees for Volatile Organic Compounds Emitted by Phaseolus vulgaris Plants Infected With Three Different Viruses
in Frontiers in Ecology and Evolution
Tungadi T
(2021)
Infection of Arabidopsis by cucumber mosaic virus triggers jasmonate-dependent resistance to aphids that relies partly on the pattern-triggered immunity factor BAK1.
in Molecular plant pathology
Adenka K
(2021)
Susceptibility of five cabbage varieties to attack by aphids (Hemiptera: Aphididae) in the Accra plains of Ghana
in Phytoparasitica
Brine T
(2023)
Investigating the interactions of endornaviruses with each other and with other viruses in common bean, Phaseolus vulgaris
in Virology Journal
Arinaitwe W
(2023)
Induction of aphid resistance in tobacco by the cucumber mosaic virus CMV?2b mutant is jasmonate-dependent.
in Molecular plant pathology
| Description | The initial field trials - and follow up work in progress (see Section 3 above) - suggest that mixtures of differentially aphid attractive/repellent grower-preferred common bean cultivars (potentially utilising existing available resistant cultivars present at a minimal frequency) could provide a viable, low tech approach to inhibiting the spread of aphids, and potentially of viruses, within mixed cropping systems, which are prevalent in east and central Africa. |
| Exploitation Route | As work on this progresses, information on these approaches will be pipelined to stakeholders by via the Pan-African Bean Research network though collaborators at CIAT. |
| Sectors | Agriculture, Food and Drink |
| Description | 2014 Gerardine Mukeshimana, the Postdoctoral Scientist working on this project at the BecA-ILRI Hub, was appointed Minister for Agriculture and Animal Resources in Rwanda in July 2014. At BecA, besides the bean project research activities, Dr. Mukeshimana was also involved in efforts in building the capacity of institutions and individuals in the African national research systems in biosciences-related crop research through knowledge transfer and resource mobilization. Before her ministerial appointment, she presented a poster on this project at the MPMI conference held between 6th -10th July 2014 in Greece. 2016-onwards. http://hub.africabiosciences.org/media-center/news/402-beca-ilri-hub-scientist-gerardinemukeshimana-appointed-minister-for-agriculture-and-animal-resources-in-rwanda Since then, the BecA-ILRI Hub team has worked with Dr Mukeshimana in her role as Minister to outline and begin implementing a more comprehensive capacity building and research program for Rwanda. In experiments under controlled conditions in which CMV-infected, aphid-infested plants were placed in proximity to mixtures of non-infected plants of Arabidopsis accessions with differing intrinsic levels of attractiveness to M. persicae, we showed that aphid migration and aphid-mediated CMV transmission can be manipulated to either enhance or inhibit spread of the insects themselves and of the virus that they carry (Bravo, Donnelly, Pate et al. unpublished). This is shown by simple experiments with Arabidopsis using Col-0, an accession that is less attractive to M. persicae than accession Ei-2. If CMV-infected plants at the start of the line (position '0') are infested with M. persicae & placed next to lines of uninfected plants, aphids migrate furthest and transmit the virus to the most plants if 'Plant 0' is of a less attractive line and adjacent plants are attractive (Ei-2, for example). This work moved on to more complex '2-dimensional' plant arrangements, which backed up the results of the 'line' experiments, showing that aphids spread and virus transmission could be inhibited or promoted, depending up the plant mixture and spatial arrangements used. Inclusion of resistant plants (using transgenic plants that are resistant to CMV) showed that it is not necessary to have 100% resistant plant populations to 'sanitize' (i.e. allow the vector to lose any inoculum) aphids so that they cease to transmit virus. This opens the way to devising seed mixtures that can inhibit virus infection whilst avoiding placing selective pressures on viruses to overcome resistance, while the method also avoids applying any selective pressure on the vectors. We believe this could be the basis of new sustainable crop protection practices that would be compatible both with smallholder, mixed cropping cultivation or with larger scale commercial farming. This data was used as proliminary finding in seeking further funding under GCRF. 2016/2017. Dr. Wamonje completed the bioinformatic analysis of our aphid viral metagenomics and molecular identification of aphids present in aphids present in smallholder farmers' fields in Kenya (from his field surveys with JPC in 2014). He used a PCR-based technique to identify aphids prevalent in smallholder bean farms and next generation sequencing shotgun metagenomics to examine the diversity of viruses present in aphids and in maize leaf samples. Samples were collected from farms in Kenya in a range of agro-ecological zones. Molecular species identification using PCR and Cytochrome oxidase 1 (CO1) gene sequencing showed that Aphis fabae was the sole aphid species present in bean plots in the farms visited. Sequencing of total RNA from aphids using the Illumina platform detected three dicistroviruses. Maize leaf RNA was also analysed. Identification of aphid lethal paralysis virus (ALPV), Rhopalosiphum padi virus (RhPV) and a novel Big Sioux River virus-like dicistrovirus in aphid and maize samples was confirmed by RT-PCR. Phylogenetic, nucleotide and protein sequence analyses of eight ALPV genomes revealed evidence of intra-species recombination with the data suggesting there may be two ALPV lineages. Analysis of BSRV-like virus genomic RNA sequences revealed features that are consistent with other dicistroviruses and that it is phylogenetically closely related to dicistroviruses of the genus Cripavirus. The discovery of ALPV and RhPV in aphids and in plants (which these viruses use as a reservoir for infection of feeding aphids) further demonstrates the broad host range of these dicistroviruses. This is the first report of these viruses being isolated from either host. Our BSRV-like sequences are potentially a novel dicistrovirus infecting A. fabae. The work has potential for the future development of biocontrol of aphids and has been drafted for journal submission (see Wamonje et al. 'Metagenomics of aphids present in bean and maize plots on mixed-use farms in Kenya reveals low aphid diversity and existence of three Dicistroviruses including a novel Big Sioux River virus-like dicistrovirus' Virology Journal 2017) and constitutes part of Dr Wamonje's PhD thesis. An additional capacity building benefit of the research was that we were able to offer the filed technician of our CIT-Uganda partners, Mr Warren Arinaitwaye, a Cambridge in Africa PhD studentship. He began his studies on aphid-plant-virus interactions in October 2017. |
| First Year Of Impact | 2014 |
| Sector | Agriculture, Food and Drink,Education |
| Impact Types | Societal,Policy & public services |
| Description | Cambridge-Africa Alborada Research Fund |
| Amount | £6,260 (GBP) |
| Organisation | University of Cambridge |
| Department | Alborada Research Fund |
| Sector | Academic/University |
| Country | United Kingdom |
| Start | 10/2015 |
| End | 09/2016 |
| Description | Isaac Newton Trust |
| Amount | £19,202 (GBP) |
| Funding ID | Newton Trust Grant reference no. 12.07(1) |
| Organisation | University of Cambridge |
| Sector | Academic/University |
| Country | United Kingdom |
| Start | 10/2012 |
| End | 12/2012 |
| Description | Biosciences east and central Africa Hub at ILRI Nairobi Kenya |
| Organisation | CGIAR |
| Department | International Center for Tropical Agriculture |
| Country | Colombia |
| Sector | Charity/Non Profit |
| PI Contribution | This lab and partners work on a SCPRID-funded programme to apply outputs of previous BBSRC-funded projects on virus and virus-plant-aphid interactions (respectively BB/D008204/1A viral counter defence protein as a probe for cross-talk or functional overlap between host defence pathways and BB/F014376/1 Subversion of insect resistance: A novel role for a plant viral silencing suppressor ) to investigate how the transmission of viruses by aphids might be disrupted in an African context. The programme is explained in layperson terms at http://www.bbsrc.ac.uk/web/FILES/Publications/1210-scprid.pdf |
| Collaborator Contribution | The cambridge group provides experimental (Carr, Baulcombe) and Modelling (Gilligan) expertise. Rothamsted (Bruce, Pickett) provides expertise in semiochemicals. BecA-ILRI provide expertise in application of biotech in an African context and CIAT expertise in bean as a crop and fieldwork. |
| Impact | The grant is still in progress- two annual reports have been provided to BBSRC via Amanda Read (BBSRC, SO) A number of publications/meeting abstracts have been generated - submitted elsewhere in this (complicated) system. |
| Start Year | 2013 |
| Description | Biosciences east and central Africa Hub at ILRI Nairobi Kenya |
| Organisation | Rothamsted Research |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | This lab and partners work on a SCPRID-funded programme to apply outputs of previous BBSRC-funded projects on virus and virus-plant-aphid interactions (respectively BB/D008204/1A viral counter defence protein as a probe for cross-talk or functional overlap between host defence pathways and BB/F014376/1 Subversion of insect resistance: A novel role for a plant viral silencing suppressor ) to investigate how the transmission of viruses by aphids might be disrupted in an African context. The programme is explained in layperson terms at http://www.bbsrc.ac.uk/web/FILES/Publications/1210-scprid.pdf |
| Collaborator Contribution | The cambridge group provides experimental (Carr, Baulcombe) and Modelling (Gilligan) expertise. Rothamsted (Bruce, Pickett) provides expertise in semiochemicals. BecA-ILRI provide expertise in application of biotech in an African context and CIAT expertise in bean as a crop and fieldwork. |
| Impact | The grant is still in progress- two annual reports have been provided to BBSRC via Amanda Read (BBSRC, SO) A number of publications/meeting abstracts have been generated - submitted elsewhere in this (complicated) system. |
| Start Year | 2013 |
| Description | Role of aphids in the transmission of a suspected viral disease and the disease's impact on the growth and yield of cabbage in Ghana |
| Organisation | University of Ghana |
| Country | Ghana |
| Sector | Academic/University |
| PI Contribution | A new disease in Ghana affecting the cabbage cash crop has been noted. Likely viral aetiology and associated with unusual build up of aphids on diseased plants. The team aims were as follows: 1. Identify the pathogen causing a novel disease of cabbage in Ghana 2. Elucidate the role of aphids in transmitting this disease 3. Assess the impact of this disease on the growth and yield of cabbage in Ghana |
| Collaborator Contribution | Helped with field surveys, site locations and transport. |
| Impact | Work in progress. |
| Start Year | 2015 |
| Description | Role of poleroviruses in maize lethal necrosis epidemics in Africa, a case study of Kenya |
| Organisation | Kenya Agriculture & Livestock Research Organization (KALRO) |
| Country | Kenya |
| Sector | Private |
| PI Contribution | Experience gained on insect vector identification while working on 'Targeting virus transmission in a vital crop for African food security' and the previous SCPRID grant by the Cambridge UK (PI, Carr) group has enabled us to form a new collaboration with Drs Jane Waimatha and Paul Kuria to investigate the possible involvement of an aphid-transmitted polerovirus in the elicitation of a novel disease of maize in Kenya. The work is funded by the GCRF-CONNECTED Network (https://www.connectedvirus.net/). Details of the project are in the next text box. |
| Collaborator Contribution | Maize, the most important cereal crop and dietary carbohydrate source in Kenya, is seriously threatened by maize lethal necrosis (MLN) disease, which causes crop losses of up to 100%. MLN results from double infection by Maize chlorotic mottle virus (MCMV) and (most typically) the potyvirus Sugar cane mosaic virus (SCMV). These viruses 'synergize' i.e. cause worse symptoms than either virus alone. The Co-Is discovered that MLN and a novel disease (atypical MLN: AMLN) may also be caused by synergy between MCMV and other viruses, including a polerovirus, Maize yellow dwarf virus-RMV (MYDV-RMV). MCMV is beetle-vectored but SCMV & MYDV-RMV are aphid-transmitted, but which insect species are the most important vectors is unknown. This presents a serious barrier to understanding MLN/AMLN epidemiology and improving disease control. The Co-Is also found that Kenyan SCMV strains are highly diverse, explaining the inadequacy of current diagnostics. Our three packages will create a platform for future work to identify, combat and eradicate MLN/AMLN. Work Package 1. We will determine definitively if MYDV-RMV synergizes with MCMV using next-generation sequencing to identify viruses in plants with MLN/AMLN, and by recreating mixed infections under controlled conditions. Work Package 2. We will identify vector species transmitting MLN/AMLN-associated viruses by DNA barcoding and use next-generation sequencing to identify viruses carried by potential vectors present in MLN/AMLN-affected fields in Kenya. Work Package 3. We will utilize the Co-I's single nucleotide polymorphism and polyprotein sequence analyses to improve diagnostics for the three distinct groups of SCMV in Kenya. This is vitally important throughout sub-Saharan Africa for tracking MLN and to aid breeders in development of MLN/SCMV-resistant maize lines. Achieving Impact. Using KALRO's plant health outreach network and media contacts, key information on MLN diagnosis and control will be disseminated to Kenyan farmers, consumers and policymakers. |
| Impact | The work is currently in progress. So far there has been a visit by Carr (UK PI) to KALRO and field sites to provide training in capture/sampling of insect viral vectors and preparation of material for sequencing and viral metagenomics. |
| Start Year | 2018 |