Banana fruit crop is one of the most valued commodities in the agriculture export industry. Fusarium wilt disease also well known as the Panama disease has been plaguing this industry since 1919. Its causal agent, Fusarium oxysporum f. sp. cubense (Foc) is a highly destructive and a variable pathogen for which no effective control measure exists. The durability of a sustainable management strategy depends on the pathogen population structure. In this study 55 Foc isolates from nine different banana farms of district Thatta of Pakistan were investigated for morphological and genetic diversity. The Foc isolates under study produced septate to unseptate microconidia, monophialides, sickle shaped 3-5 septate macroconidia with basal foot, and globose chlamydospores present singly, in pairs or in chains. Pigmentation in colonies varied from white, purple, salmon pink to peach. The optimum temperature for colony growth and sporulation was 25°C. The growth rate among the Foc isolates ranged from 6 to 8 days. Foc isolates mostly exhibited good to medium sporulation rate. No statistical correlation was observed between growth rate and sporulation potential. Out of six, only five ISSR primers amplified and generated 42 scorable bands ranging from 350bp to 2.5Kb in sizes and 40 were polymorphic (83.4% to 100%). Structure software revealed a genetic admixture population structure with low level of variation among the isolates. UPGMA dendrogram clustered Foc population into two major clades. The present study reports low levels of diversity in Pakistani Foc isolates at both morphological and genetic level.
