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Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), is recognized as one of the most devastating diseases affecting banana cultivation worldwide. In India, Foc extensively affects Malbhog banana (AAB genomic group) production. In this study, we isolated 25 Foc isolates from wilt-affected Malbhog plantations inIndia. A pathogenicity test confirmed the identity of these isolates as Foc, the primary causative agent of wilt in bananas. The morpho-cultural characterization of Foc isolates showed large variations in colony morphological features, intensity, and pattern of pigmentation, chlamydospores, and conidial size. The molecular identification of these isolates using Race1- and Race4-specific primers established their identity as Race1 of Foc, with the absence of Tropical Race 4 of Foc. For a more comprehensive understanding of the genetic diversity of Foc isolates, we employed ISSR molecular typing, which revealed five major clusters. About 96% of the diversity within the Foc population indicated the presence of polymorphic loci in individuals of a given population evident from the results of Nei’s genetic diversity, Shannon’s information index, and the polymorphism information content values, apart from the analysis of molecular variance (AMOVA). The current findings provide significant insights toward the detection of Foc variants and, consequently, the deployment of effective management practices to keep the possible epidemic development of disease under control along the Malbhog banana growing belts of northeast India. Full article

Fusarium wilt of banana (FWB), caused by Fusarium oxysporum f. sp. cubense (Foc), is the most important constraint of the banana industry globally. In Nepal, epidemics resembling FWB have been increasingly observed on the Malbhog cultivar in the past several years. However, the disease has not been officially reported yet, and consequently, little is known about the pathogen present across the country. In this study, we characterized 13 fungal strains isolated from banana plants of the Malbhog cultivar (Silk, AAB) showing symptoms similar to FWB in banana plantations in Nepal. All of the strains were typed as belonging to the F. oxysporum and caused FWB symptoms when inoculated in the Malbhog and Cachaco (Bluggoe, ABB) cultivars. No symptoms were observed in the Williams cultivar (Cavendish, AAA). Vegetative compatibility group (VCG) analysis classified the strains as VCG 0124 or VCG 0125. PCR analyses conducted with primers specific for Foc race 1 (Foc R1) or Foc tropical race 4 (TR4) revealed that all the strains reacted positively for Foc R1 and none for TR4. Altogether, our results demonstrated that the pathogen populations causing FWB of the Malbhog cultivar in Nepal were Foc R1. This work reported, for the first time, the occurrence of FWB in Nepal. Further studies with larger Foc populations are needed to better understand disease epidemiology to design sustainable disease management strategies. Full article