Molecular Identification and Pathogenicity of Fusarium Species Associated with Tuber Rot Disease of White Yam (Dioscorea rotundata Poir) in Nigeria

Abstract

This study investigated Fusarium species associated with postharvest soft rot disease of white yam (Dioscorea rotundata Poir) and their pathogenic status in Nigeria. Isolates were obtained from tubers showing rot symptoms in nine States in 2023 and 2024. Initial identification was carried out using morphological characteristics, while 29 representative isolates were selected for molecular analyses based on prevalence and pathogenicity. Phylogenetic analysis using partial sequences of the translation elongation factor (TEF1α) gene region was conducted using specific primer pair EF1(5՜-ATGGGTAAGGAGGACAAGAC-3՜) and EF2 (5՜-GGAAGTACCAGTGATCATGTT-3՜). The sequence analysis identified 22 of the isolates as F. oxysporum, while the remaining seven isolates belonged to four other species, F. proliferatum, F. equiseti, F. avenaceum and F. solani. Phylogenetic tree analysis showed interrelatedness among Fusarium oxysporum isolates across geographical origin with close similarity with F. oxysporum strain KY224029.1, while genetic dissimilarity was recorded among seven other Fusarium species. These findings provide a molecular basis for breeding and disease management. This study confirmed pathogenicity of F. oxysporum isolates and also provides first report on F. equiseti as yam rot pathogen in Nigeria.