Molecular characterization of species associated with Teratosphaeria canker of Eucalyptus hybrid clones in Matugga, Wakiso district

Abstract

The dwindling natural forest cover and the corresponding wood shortage in Uganda have necessitated investment in plantation forestry in which Eucalyptus hybrid clones are an important component. Successful establishment of these clonal hybrids however may be threatened by the widely spread Teratosphaeria canker disease. Teratosphaeria canker was first reported from South Africa and since then, the disease has subsequently been found on various species and hybrid clones of Eucalyptus in other African countries as well as in South American and South-East Asian countries. Symptoms similar to those of Teratosphaeria stem canker were observed on Eucalyptus hybrid clones in Matugga, Wakiso district thus the aim of the study was to characterize species associated with the canker disease in Matugga. Symptomatic twigs from Eucalyptus hybrids infected with Teratosphaeria canker were collected from Matugga in Wakiso, central Uganda. Fungi were isolated into pure cultures. Colony appearances on MEA plates were observed and noted. DNA was extracted from pure cultures and the ITS gene region amplified. PCR amplicons were sanger sequenced and sequence data were analyzed. The analysis of sequence data revealed three species causing Teratosphaeria canker to Eucalyptus hybrids in Matugga, Wakiso district as Teratosphaeria gauchensis, Teratosphaeria zuluensis and a Cercospora species represented by nine isolates. T. zuluensis and T. gauchensis had been earlier reported causing Teratosphaeria canker in various parts of the world where Eucalyptus species and hybrids are cultivated. The Cercospora species reported by the study has never been reported causing Teratosphaeria canker on Eucalyptus species and clones thus further studies should be conducted to characterize the isolate to species level as well as understand its pathogenicity on Eucalyptus species. Further studies should as well be conducted to understand the pathogenicity of Teratosphaeria gauchensis and Teratosphaeria zuluensis on Eucalyptus clones grown in Uganda to identify tolerant material for growing in high disease pressure areas.