Caracterização morfológica, molecular e patogênica do agente etiológico da fusariose do abacaxizeiro no Brasil

Abstract

Fusarium guttiforme, a member of Gibberella fujikuroi Complex (GFC), is considered the causal agent of fusariosis in pineapple and fruit rot. The objective of this work was to characterize isolates of F. guttiforme obtained from plants of pineapple with symptoms of fusariosis collected in different pineapple producing regions using morphological markers, phylogenetics and pathogenicity tests. The phylogenetic analysis was done with partial sequences of the beta tubulin gene (tub2) and elongation factor 1α (tef1), including sequences of the type and reference material from different species of GFC. The pathogenicity test was realized in slips of pineapple under controlled condition of temperature and humidity. Forty nine isolates were evaluated morphologically and identified as F. guttiforme. It was not possible to identify phenotypic variants among isolates of this study. All of the isolates identified as F. guttiforme grouped with representative isolates of Fusarium obtained from pineapple. In the combined analysis of maximum parsimony and Bayesian inference, reference sequences of F. ananatum were added, a species described recently in South Africa as etiological agent of fruit rot. In addition, a group of isolates, paraphyletic "para-ananatum", was observed. The rest of the isolates of this study was observed in polytomy, therefore it was not possible to infer the phylogenetic relationships. Most of the isolates studied induced necrosis in slips of pineapple. Based on the results of this study, there is evidence of the existence of three phylogenetically distinct lines of Fusarium associated to pineapple in Brazil. However, the genomic regions evaluated did not have sufficient resolution to confirm this hypothesis.