Viruses Infecting Cassava in Kenya

Area of Science:

• Plant Virology
• Agricultural Entomology
• Molecular Biology

Background:

• Cassava viruses pose a significant threat to food security in Africa.
• Begomoviruses, such as African cassava mosaic virus (ACMV), are well-known cassava pathogens.
• The presence and impact of other cassava viruses in Kenya remain underexplored.

Purpose of the Study:

• To survey and identify viruses affecting cassava in key Kenyan growing regions.
• To characterize the diversity and prevalence of cassava viruses, including begomoviruses and filamentous viruses.
• To assess the pathogenicity of identified viruses in experimental hosts.

Main Methods:

• Collection and analysis of 185 leaf and 62 stem cutting samples from symptomatic cassava plants.
• Utilized biological assays, electron microscopy, enzyme-linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR).
• Inoculation of identified viruses into Nicotiana benthamiana and back-inoculation onto cassava.

Main Results:

• Cassava begomoviruses (ACMV, East African cassava mosaic virus [EACMV], EACMV-UG) were prevalent in western Kenya.
• EACMV was the sole begomovirus detected in the Coast region.
• Fifteen samples showed mixed infections of EACMV and three novel filamentous viruses (200-750 nm).
• Filamentous viruses, potentially from the Potyviridae family, induced severe symptoms and high mortality in N. benthamiana.

Conclusions:

• This research confirms the presence of both begomoviruses and significant filamentous viruses in Kenyan cassava.
• Filamentous viruses, previously unidentified, are pathogenic and could pose a serious threat to cassava production.
• Findings underscore the importance of comprehensive viral diagnostics and integrated management strategies for cassava in Africa.