| Summary: | Coffee corky-root disease causes serious damages to coffee crop and is linked to combined infection of <i>Fusarium</i> spp. and root-knot nematodes <i>Meloidogyne</i> spp. In this study, 70 <i>Fusarium</i> isolates were collected from both roots of healthy coffee plants and with corky-root disease symptoms. A phylogenetic analysis, and the detection of pathogenicity <i>SIX</i> genes and toxigenicity <i>Fum</i> genes was performed for 59 <i>F. oxysporum</i> and 11 <i>F. solani</i> isolates. Based on the molecular characterization, seven <i>F. oxysporum</i> and three <i>F. solani</i> isolates were assessed for their pathogenicity on coffee seedlings under optimal watering and water stress miming root-knot nematode effect on plants. Our results revealed that a drastic increment of plant colonization capacity and pathogenicity on coffee plants of some <i>Fusarium</i> isolates was caused by water stress. The pathogenicity on coffee of <i>F. solani</i> linked to coffee corky-root disease and the presence of <i>SIX</i> genes in this species were demonstrated for the first time. Our study provides evidence for understanding the pathogenic basis of <i>F. oxysporum</i> and <i>F. solani</i> isolates on coffee and revealed the presence of <i>SIX</i> and <i>Fum</i> genes as one of their pathogenicity-related mechanisms. We also highlight the relevance of chlorophyll, a fluorescence as an early and high-throughput phenotyping tool in <i>Fusarium</i> pathogenicity studies on coffee.
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