Document Type Doctoral Thesis Author Pakela, Yolisa Patronella URN etd-09022005-102127 Document Title Interaction between Colletotrichum dematium and cowpea Degree PhD (Botany) Department Botany Supervisor
Advisor Name Title Prof T A S Aveling Committee Chair Prof T A Coutinho Committee Co-Chair Keywords
- fungal diseases of plants
- cowpea diseases and pests
Date 2003-04-12 Availability unrestricted AbstractAnthracnose of cowpea (Vigna unguiculata (L.) Walp) caused by Colletotrichum dematium (Pers. ex Fr) Grove has serious socio-economic implications. Subsistence farmers rely heavily on cowpea for protein and fodder; therefore, C. dematium poses a threat to production of this crop. The purpose of this study was to investigate the interaction between cowpea and C. dematium. Investigations involved characterising C. dematium field isolates using morphological and molecular techniques, infection studies, biochemical and histochemical analysis and determining factors that influence the severity of the fungus on the host. Random amplified microsatellite profiles of C. dematium grouped the isolates into eleven groups linked to morphological characteristics, pathogenicity and geographic origin. Infection studies indicated that C. dematium is a subcuticular intramural coloniser, that switches to destructive necrotrophy. Pulvinate acervuli were produced at 72 hours post inoculation over water-soaked lesions and complete necrosis of the host tissue occurred at 120 hours. The infection process was favoured by prolonged periods of high humidity and high temperatures, especially in cowpea plants between the ages six to nine-weeks-old. Investigations on the location and patterns of polyphenols in the cowpea seed coats indicated that brown coloured cowpea cultivars contained more soluble phenolic compounds than cream coloured cultivars and they were more resistant to C. dematium.
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Please cite as follows:
Pakela, YP 2003, Interaction between Colletotrichum dematium and cowpea, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-/ >
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