[1] Univ Pretoria, Dept Genet, ZA-0002 Pretoria, South Africa
[2] Univ Pretoria, Tree Pathol Cooperat Programme, ZA-0002 Pretoria, South Africa
[3] Univ Pretoria, Forestry & Agr Biotechnol Inst, ZA-0002 Pretoria, South Africa
[4] Univ Orange Free State, Dept Microbiol & Biochem, ZA-9300 Bloemfontein, South Africa