Maize streak virus

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Maize streak virus (MSV) is a plant pathogen that affects maize (corn) and other members of the family Poaceae. It is a member of the genus Mastrevirus, within the family Geminiviridae. MSV is responsible for causing Maize streak disease, a significant agricultural problem in Sub-Saharan Africa, where maize is a staple food crop. The virus is transmitted by leafhoppers, specifically the Cicadulina species, in a persistent circulative non-propagative manner.

Symptoms and Effects

Infected maize plants exhibit a range of symptoms including chlorotic streaks on the leaves, which can lead to severe stunting of the plant and, in extreme cases, death. The severity of the symptoms and the impact on crop yield depend on the age of the plant at the time of infection, with younger plants being more severely affected. The disease can lead to significant losses in maize production, affecting food security and the economy in affected regions.

Transmission and Spread

The primary vector for MSV is the Cicadulina mbila leafhopper, which acquires the virus by feeding on infected plants and can transmit it to healthy plants. The virus is spread as these leafhoppers move from plant to plant, feeding. The spread of MSV is influenced by factors such as the population density of the vector, the presence of alternative host plants, and climatic conditions, particularly temperature and humidity, which can affect the lifecycle of the vector and the virus.

Management and Control

Management of Maize streak virus involves an integrated approach combining cultural, biological, and chemical methods. Cultural practices include the removal and destruction of infected plants and the use of resistant maize varieties. Biological control methods focus on managing the population of the vector, while chemical control involves the use of insecticides to reduce vector populations. However, the reliance on chemical control is less favored due to concerns about environmental impact and insecticide resistance.

Research and Development

Research into MSV has focused on understanding the virus's genetics, the mechanism of transmission by its vector, and the development of resistant maize varieties. Genetic engineering and conventional breeding have both been explored as methods to develop maize varieties that are resistant to MSV. Advances in biotechnology, such as CRISPR/Cas9 gene editing, offer promising avenues for creating resistant maize varieties, although these technologies are subject to regulatory, ethical, and acceptance issues in different regions.

Economic and Social Impact

The economic and social impact of Maize streak virus in Sub-Saharan Africa is significant, as maize is a major food crop in the region. Outbreaks of the disease can lead to substantial losses in maize production, affecting food security, farmer income, and the overall economy. Efforts to control the virus and develop resistant maize varieties are crucial for improving food security and livelihoods in affected areas.