Identification of pathogenic fungal isolates of the Fusarium oxysporum and the Fusarium fujikuroi species complex, causing fusariosis in ornamental pineapple, and antifungal activity of elicitors

Pineapples are herbaceous tropical perennial plants of the genus Ananas (Bromeliaceae). Besides the worldwide distributed edible pineapple ( A. comosus var. comosus ), some other botanical varieties of Ananas have been grown as ornamentals due to their conspicuous colorful inflorescences and fruits. However, knowledge about the pathogens that are associated with ornamental pineapples under field conditions is still scarce. The aim of this work was to isolate and characterize fungal pathogens infecting ornamental pineapples in Northeastern Brazil. The isolates were subjected to morphological characterization, molecular identification by DNA sequencing of the ITS/5.8S locus and pathogenicity trials. The effects of commercial elicitors on mycelial growth and conidia germination were also evaluated. Five isolates were obtained, exhibiting morphological features typical of Fusarium . Based on DNA sequences of the ITS/5.8S region, the isolates were classified as belonging to F . oxysporum (isolates MVA28, MVA85, MVE52 and MVE85) and the F . fujikuroi species complex (isolate MVE89). All isolates were able to infect ornamental pineapple leaves of hybrid D ( A. comosus var. bracteatus × A. comosus var. erectifolius ) and Lucidus ( A. comosus var. erectifolius ), producing typical fusariosis lesions. Some commercial elicitors showed in vitro antifungal activity against the Fusarium isolates, inhibiting their mycelial growth and conidia germination.