Relationship between symptoms expression and virus detection in cassava brown virus streak-infected plants
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Date
2012
Journal Title
Journal ISSN
Volume Title
Publisher
Canadian Center of Science and Education
Abstract
Diagnosis of Cassava brown streak disease (CBSD) has for long been based on foliar and root symptoms
expression on infected plants. Variability in patterns of symptoms expression between varieties and seasons
however, has meant that symptom-based diagnostics are unreliable. The current study established the relationship
between symptom expression on cassava plants and the infection with Cassava brown streak virus (CBSV) using
RT-PCR diagnostic tool. It was established that manifestation of CBSD-like symptoms (particularly the foliar
chloroses and necrotic blotches) may not be an absolute indication of CBSV-infection. Only 67% of tested samples
were both foliarly symptomatic and infected by the virus. About 22% of samples were free from CBSV despite
being foliarly symptomatic and 7% were CBSV-infected but foliarly symptom less. Some CBSV-infected plants
did not exhibit any foliar symptoms although had root necroses. A few CBSV-free plants were regenerated from
infected cuttings in one of the four tested cultivars, Albert. Five out of fifteen (33%) plants cv. Albert were
symptom less and two out of the five (40%) were CBSV-free. The findings from this study suggest that
symptoms-based diagnosing for CBSV infections is unreliable. As some of CBSV-infected plants tend to be
considered CBSV-free due to lack of the disease symptoms, the scenario might have contributed to unlimited
spread of CBSD through latently-infected planting materials.
Description
Journal Article
Keywords
Cassava brown streak disease, Cassava brown streak virus, RT-PCR, symptomatology, virus distribution in plant parts