MLN Workshop: Overview on maize lethal necrosis -- A Wangai
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Maize Lethal Necrosis Disease (MLND) is caused by a combination of Maize chlorotic mottle virus (MCMV) and Sugarcane mosaic virus (SCMV) or other potyviruses. The document provides an overview of MLND, including its symptoms such as chlorotic leaf mottling, stunting, and premature death. It discusses the global history and spread of MLND since the 1930s. While MLND causes major losses to food security and economies, further research is still needed to understand aspects like alternative hosts, the role of other pathogens and stresses, and transmission mechanisms. Several partner institutions in Kenya and internationally are collaborating on MLND research activities.
MLN Workshop: Overview on maize lethal necrosis -- A Wangai
- 1. Maize Lethal Necrosis Disease (MLND) An Overview of the disease affecting maize TRAINING WORKSHOP ON MLN DIAGNOSIS AND MANAGEMENT 17th -19th MARCH 2015 Dr Anne Wangai
- 2. Contents •Causal agents •Global history •Symptoms •Disease occurrence & effects
- 3. MLND Causal agents Maize chlorotic mottle virus (MCMV) Sugarcane mosaic virus (SCMV) or other Potyviruses What is causing the maize disease?
- 4. Sugarcane mosaic virus Family: Potyviridae Genus: Potyvirus Species: Sugarcane mosaic virus Acronym: SCMV
- 5. Maize chlorotic mottle virus-(MCMV) Family: Tombusviridae Genus: Machlomovirus Species: Maize chlorotic mottle virus Acronym: MCMV
- 6. MLN disease development Environmental conditions: Favouring vectors and pathogen Virus: Either single or compound Germplasm: Susceptible/Resist ant Vectors/seed / other transmission RATE OF DISEASE DEVELOPMENT
- 7. Disease Outbreak •SCMV described in Eastern Africa in 1930’s •MCMV first detected in Kenya in 2012.
- 8. Country Year Reference Peru 1973 Castillo and Hebertt (1974) USA 1976 Niblett and Cafflin (1976) Argentina 1982 Teyssandier et al. (1982) Mexico 1987 Delgadillo and Gaytan (1987) Brazil 1983 Cited in Uyemoto (1983) Thailand 1983 Cited in Uyemoto (1983) China 2011 Xie et al. (2011) Kenya 2012 Wangai et al. (2012 Tanzania 2012 CIMMYT TF Rept to Ministry of Agriculture, Tanzania Uganda 2012 G. Asea, Workshop (Nairobi; Feb 12-13, 2013) Rwanda 2013 C. Ngabiyasonga, MLN Training Workshop (Nairobi; 2013) DRC 2014 Kumar , FAO Regional Meeting, Nairobi, 2014 Ethiopia 2014 CIMMYT T-Force Rept to Ministry of Agriculture, Ethiopia ?????? ? Introduction: Trend of global occurrence of MLND (CLND)
- 9. •Mild mosaic, •Systemic chlorotic leaf mottling •Severe stunting, •Leaf necrosis, •Premature plant death, •Shortened male inflorescences with few spikes, •Shortened, malformed, partially filled ears •Mixtures of MCMV with any of several potyviruses also causes necrosis, stunting and death. Typical symptoms of MCMV
- 10. FIELD CROP INFECTED BY MLND
- 11. Maize leaves: MLND VS HEALTHY
- 12. Severe chlorotic mottle on the leaves
- 13. Chlorotic mottle on leaves –parallel to the mid vein
- 14. Chlorotic stripes and mottle on leaves
- 15. Bleaching of leaf margins and mottle
- 16. Broad chlorotic banding on leaves
- 19. Poor or no grain filling
- 20. Husks dry prematurely, no grain
- 21. Losses along Value chain Food and economic security threatened Losses for seed producers (for both growers and seed companies) Millers (both in quality and quantity) Transporters (reduced volume of business) Storage facilities (dormant capacity) Middlemen (loss of business volumes)
- 22. Host range
- 23. WAY FORWARD- What We Do not Know • MLND-Where to Next? • MCMV resistance in maize germplasm • MCMV variability • Extent seed transmission contribute to the introduction/ spread/ sustaining disease in the region • Alternative hosts (reservoirs) for MCMV/SCMV. • Role of Maize streak virus and other pathogens/stresses factors in MLN epidemic. • Full range of other viruses present in the maize-growing systems • MLND contribution to elevated Mycotoxins in maize grainRole of maize thrips, beetles, other insects/nematodes in MLN outbreak. • The extent of MCMV transmission through Soil/water/plant debris/plant to plant transmission?
- 24. PARTNER INSTITUTIONS COLLABORATORS MoAL &F KARI KEPHIS PCPB UoN CIMMYT icipe BecA STAK CGA OARDC- Ohio State University, USA University of Minnesota, USA CABI Food and Environment Research Agency (FERA), UK Cambridge University, UK Institutions in MLND research activities Government Organizations International Research Organizations Private Organizations
- 25. Acknowledgement •Director KALRO •KAPAP •MLND Technical Team •MoA&L •CIMMYT