Trichoderma, biodiversidade e aplicação no controle da fusariose do abacaxizeiro: caracterização molecular de agentes de biocontrole (Trichoderma spp.) de Fusarium guttiforme

Abstract

Pineapple (Ananas comosus) is one of the few agricultural alternatives for the Brazilian Northeast. Pineapple fusariosis caused by Fusarium guttiforme (Fgt) causes severe losses and is the main limiting factor for pineapple production. Trichoderma spp. have been successfully applied in the control of various plant pathogens and for this reason is considered to be an alternative to chemical. However, research aiming at the biocontrol of Fgt is scarce. In this research, Trichoderma spp. were isolated from plant species of the Caatinga and tested against Fgt. Isolates with potential for biological control were selected by in vitro and greenhouse tests (Chapter 1). In the field, isolates TC77 (953.30 g), TC26 (951.05 g) and TC36 (927.23) provided higher rates of disease control as expressed in average fruit weight (Chapter 2). BOX-PCR analysis of Trichoderma spp. originated 14 genetic groups (Grg), which were tested for biocontrol of Fgt in vitro. Grg 3 (TC09), Grg 9 (TC10) and Grg 5 (TC14) showed higher capacity to reduce pathogen colonization. Fragment of ITS region of rDNA and translation and elongation factor 1 alpha of the RNA of each isolate were used in a preliminary phylogenetic analyzes. The TC26 and TC36 (Grg10) isolates were identified as T. koningiopsis and isolated TC77 (Grg09) as T. atroviride. Trichoderma longibrachiatum and other 6 undescribed species were found among the isolates studied. New species were represented by isolates TC06, TC23, TC26 and TC93. In the near future formulations of these isolates may be used commercially, which justifies new studies aimed at the identification and description of the new species.