A significant threat to food security in sub-Saharan Africa, maize streak disease (MSD), continues to impact maize production, particularly in the Democratic Republic of Congo. The disease, caused by the maize streak virus (MSV), has been a persistent challenge for decades, with outbreaks causing substantial yield losses.
MSV, classified within the Geminiviridae family and the Mastrevirus genus, primarily affects maize but can also infect over 80 other wild and domesticated grasses. The virus is transmitted by leafhoppers, specifically Cicadulina mbila and other Cicadulina species like C. Storeyi, C. Arachidis, and C. Dabrowski. The A-strain of MSV (MSV-A) is responsible for sporadic epidemics across the African continent.
First documented in 1901 by South African entomologist Claude Fuller, who termed it “mealie variegation,” MSD prompted efforts to develop resistant maize varieties beginning in the 1950s in countries including Kenya, Nigeria, and South Africa. Breeding for resistance has proven complex due to the multiple genes involved. While conventionally resistant varieties have seen some success, the emergence of novel viral strains and vector populations continues to pose a challenge.
Research published in 2011 reconstructed the history of MSV-A dispersal, tracing its origins to Southern Africa. The study, conducted by researchers at the University of Cape Town and other institutions, aimed to identify diversification hotspots and understand the spread of the virus across the continent. Understanding the virus’s history is crucial for developing effective control strategies.
Efforts to develop genetically modified (GM) maize varieties resistant to MSV in South Africa were discontinued before field trials could be completed. Despite this setback, maize streak resistance remains a key trait for breeders. Forward genetics is increasingly being utilized in the search for improved resistance genes.
The impact of MSD extends beyond immediate crop losses, contributing significantly to food security challenges throughout Africa. The virus’s endemic presence in sub-Saharan Africa and neighboring Indian Ocean territories, including Madagascar, Mauritius, and La Reunion, underscores the need for ongoing surveillance and research to mitigate its effects.
