Wilt Disease on Passion Fruit in Brazil Is Caused by Members of the Fusarium oxysporum Species Complex and Fusarium udum

ABSTRACT Brazil is the largest producer and consumer of passion fruit. Among the diseases affecting this crop, Fusarium wilt is one of the most destructive. The disease is attributed to Fusarium oxysporum f. sp. passiflorae , which infects the root system and then colonizes the xylem vessels causing wilt and death of the plant. The aim of this study was to evaluate the diversity of phylogenetic lineages within the Fusarium oxysporum species complex (FOSC) that may represent causal agents of the disease. Forty‐nine strains with morphological traits of F. oxysporum obtained from diseased plants were characterized using morphological markers, molecular phylogenetic analyses of tef1 , rpb2 and cmdA gene region sequences, and pathogenicity tests. Our field strains were identified as F. triseptatum ( n = 21), F. kalimantanense ( n = 2), and members of the F. inflexum Clade ( n = 19), as well as Fusarium udum ( n = 7), a member of the F. fujikuroi species complex (FFSC). The identification of F. udum was confirmed by crossing experiments using tester strains. Representative strains included in the pathogenicity assays induced wilt symptoms when inoculated in passion fruit plants. F. udum , which shares morphological traits with members of the FOSC, is recorded for the first time as an aetiological agent of passion fruit wilt. The findings demonstrate that F. oxysporum f. sp. passiflorae represents at least four distinct fungal species in Brazilian agroecosystems. This identification supports accurate diagnosis of the Fusarium wilt pathogens and facilitates monitoring of their incidence, geographical distribution and host range.