ABSTRACT
One of the major fungal diseases affecting the pineapple crop is fusariosis, caused by the fungus Fusarium guttiforme. The use of Trichoderma spp., which are soil fungi naturally occurring as endophytic forms in Bromeliaceae, has not been studied for the biocontrol of fusariosis in pineapple plants. The present study aimed to identify Trichoderma species endophytic to Bromeliaceae in “Restinga” and to evaluate the in vitro and in vivo antagonism against F. gutifforme, the etiological agent of pineapple fusariosis. Five Trichoderma isolates were evaluated, which were stored in the Phytosanitary Clinics of the State University of North Fluminense Darcy Ribeiro (CF/UENF440, CF/UENF441, CF/UENF442, CF/UENF443 CF/UENF444). A F. guttiforme isolate, pathogenic to pineapple, was also used. For specific identification of Trichoderma spp., DNA extraction and sequencing and of ITS genes were carried out. Phylogenetic analysis was conducted and the endophytic isolates from Bromeliaceae were grouped in the Longibrachiatum section, showing low homology among the known species, which may indicate a new species that will be confirmed with the obtaining of additional sequences of specific genes. In vitro antibiosis tests were then carried out to select antagonistic isolates (antagonism in matched culture, inhibitory effect of volatile, non-volatile and non-volatile thermostable compounds) and the biological treatment of wounded pineapple fruits was evaluated with the aim of assessing the biocontrol of fusariosis in the post-harvest. The isolate CF/UENF440 was shown to be a potential in vitro biocontrol agent of F. guttiforme since it demonstrated strong antibiosis in co-cultivation culture medium, for both non-volatile and non-volatile thermostable compounds, significantly differing from the remaining tested isolates and control. Considering the evaluation of in vivo biocontrol in wounded pineapple fruits, the tested Trichoderma isolates had no significant protectant effect in the biocontrol of fusariosis in post-harvest fruits.
Keywords
Antibiosis; biological control