摘要：

In order to characterize biologically and molecularly the etiological agent of mango floral and vegetative malformation in Brazil AFLPs, sexual compatibility, sequence analysis, morphological and pathogenicity assays were used. The AFLP patterns of the majority of isolates collected in Brazil were different from Fusarium mangiferae and Fusarium sterilihyphosum, two previously described Fusarium species associated with mango malformation. The cluster analysis of AFLP data using Dice coefficient produced a network where Fusarium sp. from Brazil were in one group apart from two other groups represented by isolates of F. sterilihyphosum from Brazil and South Africa, and by isolates of F. mangiferae from Egypt, India, South Africa and USA, respectively. Fusarium sp. from Brazil was compared with 24 species of the Gibberella fujikuroi complex (GFC) using AFLP data and showed to be a distinctive species. The UPGMA network generated from the AFLP data showed a similar topology to the gene genealogies of the GFC with three phylogeographic clades, the american, african and asian. Isolates of Fusarium sp. from Brazil were sexually compatible with each other but not with F. sterilihyphosum, and neither F. mangiferae. The crosses produced by isolates of Fusarium sp. formed perithecia with oozing ascospores typical of Gibberella. Sequence analyses of portions of amp;#946;-tubulin and EF-1amp;#945; were used to elucidate the phylogenetic relationships between Fusarium sp. from Brazil and the species of the GFC. Maximum parsimony analyses grouped this Fusarium sp. in the American clade, but within a distinct subgroup wich indicates a different species close related to F. sterilihyphosum. In the morphological comparisons some isolates of Fusarium sp. from Brazil produced the coiled sterile hyphae and the same occurred with F. sterilihyphosum. These species are not easily separated when only morphological characters are used, but can be distinguished through AFLP patterns, fertility and sequence analyses. None of the studied isolates from Brazil were identified as F. mangiferae. Isolates of Fusarium sp. from Brazil and F. sterilihyphosum induced typical malformation symptoms in inoculated mango plantlets. A new species of Gibberella, associated with mango malformation in Brazil, will be described.

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