Abstract

Variation within the intergenic spacer (IGS) of the ribosomal DNA gene for twenty-two strains of F. oxysporum and its formae speciales was examined by PCR, coupled with RFLP analysis. The length of the amplified IGS region was about 2.6 kb in all strains except F. oxysporum f. sp. cucumerinum from Korea and F. oxysporum f. sp. niveum. Those two strains were 2.5 kb long. Restriction digestion of IGS-RFLP regions by EcoRI, NruI, HincII, SalI, SmaI, BglII, HindIII, XhoI, and KpnI gave rise to nine IGS haplotypes among all strains. Cluster analysis based on the presence or absence of comigrating restriction fragments show the two groups based on 44% genetic similarity. These results demonstrated that analysis of IGS showed some difference within and between F. oxysporum formae speciales.

• Keywords: Fusarium oxysporum; formae speciales; Intergenic spacer (IGS); PCR-RFLP