Molecular phylogeny and pathogenicity of Fusarium oxysporum f. Sp. elaeidis isolates from oil palm plantations in Cameroon

In Cameroon one of the crops of economic importance is oil palm (Elaeis guineensis Jacq.). However, it is affected by vascular wilt presumed to be caused by Fusarium oxysporum f. sp. elaeidis (FOE). Accurate species identification requires molecular-based comparisons. We hypothesize that FOE is the cause of oil palm wilt in Cameroon. We have tested this hypothesis by molecularly identifying Fusarium species associated with diseased oil palms and by determining the pathogenicity of selected isolates. Fungal samples of diseased palms were collected from the canopies and the soil in five oil palm estates of the Cameroon Development Corporation and characterized by sequencing and comparing the translation elongation factor 1a gene. The result revealed the presence of FOE from approximately 80% of the isolations. Cameroonian isolate within FOE clade 1 exhibited the greatest variability grouping with isolates from Suriname, Brazil and Democratic Republic of Congo. Other isolates found in FOE clade 2 formed a unique group comprised solely of isolates originating from Cameroon. Twenty-two isolates were chosen for pathogenicity tests. Within a short duration, fourteen isolates were demonstrated to be pathogenic to oil palm seedlings. These pathogenic isolates were distributed in both clade 1 and 2. This study reveals the pathogenicity of FOE isolates from Cameroon and has demonstrated that FOE in Africa is more diverse than previously reported including a lineage not previously observed outside of Cameroon. Comparisons among all isolates will ultimately aid to devise appropriate control mechanisms and better pathogen detection methods