Characterisation of Zimbabwean Armillaria using IGS-1 sequences and AFLP analysis

Abstract

Armillaria root and butt rot disease is a common problem in peach orchards, tea and pine plantations in the Eastern Highlands of Zimbabwe. The species of Armillaria causing this disease have not been fully identified but it is believed that at least three species are involved. These included A. fuscipes (previously referred to as RFLP Group I) and two unnamed species known as RFLP Group II and RFLP Group III. The aim of the study was to use PCR-RFLP, sequences of the IGS-1 region of the rDNA operon and AFLP fingerprinting to characterize 27 Zimbabwean Armillaria isolates. PCR-RFLP tests showed that the isolates resided in five groups. Analysis of sequence data elucidated four groups, which were also supported by AFLP data. Thirteen isolates belonged to RFLP Group I, which is considered to represent A. fuscipes, four isolates were most similar to those previously referred to as Zimbabwean RFLP Group II and two isolates clustered most closely with RFLP Group III. The remaining isolates appear to represent Armillaria taxa not previously found in Zimbabwe.