Antagonistic activity of fungi from anthracnose lesions on Paullinia cupana against Colletotrichum sp.

Anthracnose is a cosmopolitan disease caused by Colletotrichum spp. that affects many crops worldwide. Observations have shown that anthracnose leaf lesions may be colonized by several non-pathogenic microorganisms. The relationship of these microorganisms with the pathogen as well as their potential as biocontrol agents is not well known. Guarana (Paullinia cupana Mart. var. sorbilis) is a typical native Amazon crop with unknown microbial diversity. Guarana productivity has been reduced by a fungal disease caused by Colletotrichum sp. In this study, we isolated 15 fungi from guarana anthracnose leaf lesions that belong to five genera: Fusarium, Phomopsis, Leptosphaeria, Microdochium and Pestalotiopsis. Four isolates from the Fusarium sp. (C6 and C10), Pestalotiopsis sp. (C3), and Microdochium sp. (P7) consistently inhibited anthracnose fungal growth in vitro. Except for the Microdochium sp. (P7), these isolates were also able to inhibit the growth of the pathogen in in vivo assays using detached guarana leaves. Some mechanisms related to the growth inhibition of this pathogen were studied. Fusarium sp. (C6) produced chitinases; Fusarium sp. (C6, C10) and Pestalotiopsis sp. (C3) produced antagonistic volatile organic compounds. These three isolates also inhibited the growth of Fusarium spp., a pathogen of several plant species, suggesting their potential broad range of growth inhibition of other phytopathogens