Genetic variation in the wattle wilt pathogen Ceratocystis albofundus

Abstract

Ceratocystis albofundus is an important wilt pathogen on exotic Acacia mearnsii trees in South Africa. It is known only from this country and has also been reported from native Protea spp., but it is not clear if the pathogen is native or introduced to South Africa. This study was conducted to determine the nuclear and mitochondrial gone diversity in a population of C. albofundus and to compare this diversity with that of other Ceratocystis species. Isolates were collected from a number of geographic regions in South Africa. Total genomic DNA was extracted from each isolate, digested with Psti and probed with the radioactively labelled oligonucleotide marker (CAT)s to determine nuclear DNA diversity. For the determination of mitochondrial DNA diversity, the RFLPs of Haelll digests were scored directly without probing. Nei's gone diversity (H) was determined and a distance matrix was developed for each set of markers and analyzed using UPGMA. The C. albofundus population was found to have a high level of both nuclear and mitochondrial gone diversity when compared with published data of populations of other Ceratocystis spp. This further supports the hypothesis that C. albofundus is native to South Africa.