Genetic variation in Fusarium oxysporum f.sp. cubense isolates based on random amplified polymorphic DNA and intergenic spacer

Abstract

Fusarium oxysporum f.sp. cubense (Foc) isolates were obtained from research centers and from the hot spot of fusarium wilt ‘Nanjangud’. The morphological features like colony appearance, growth rate, pathogenicity, optimum growth temperature and vegetative compatibility grouping (VCG) were determined. Molecular characteristics of these isolates were determined using random amplified polymorphism DNA (RAPD) analysis, and polymerase chain reaction – restriction fragment length polymorphism (PCR-RFLP) analysis of nuclear intergenic spacer rDNA (IGS). All the F. oxysporum f.sp. cubense isolates were pathogenic to banana cultivar ‘Nanjangud Rasabale’ but they did not induce any disease symptoms on cultivar ‘Cavendish’. The F. oxysporum isolate did not induce wilt symptoms on either ‘Nanjangud’ or ‘Cavendish’ cultivar. Based on RAPD data, 140 scoreable markers were obtained from 36 random decamer primers. Cluster analysis with Unweighted Pair-Group Method with Arithmetic mean (UPGMA) using genetic distance showed that the isolates belonged to three main groups. In general, isolate 1, 2, 4, 5 and 7 were in one group and isolate 3 and 6 were in another group. The grouping based on IGS data correlated with the grouping of isolates based on RAPD.