Newly isolated strain of Trichoderma asperellum from disease suppressive soil is a potential bio-control agent to suppress Fusarium soil borne fungal phytopathogens

Abstract

Trichoderma sp. was isolated from the rhizosphere soil of a healthy banana plant grown in a Panama disease-contaminated field (suppressive soil). The selected strain, identified as Trichoderma asperellum, exhibited antifungal activity against four species of phytopathogenic fungi from the Fusarium genus (F. oxysporum, F. fujikuroi, F. tricinctum, F. cantenulatum). Antagonism related mechanisms associated with the T. asperellum isolate against four fungal phytopathogens were studied in vitro both indirectly by the observation of growth competition and directly by antibiosis and mycoparasitism. It was shown that T. asperellum could suppress growth of phytopathogens in the range of 65–74%, as well as inhibits spore germination by 30- 75%. Moreover, T. asperellum was demonstrated to secrete mycolytic enzymes (chitinase and β-1,3, glucanase), which are potentially able to degrade cell walls of the phytopathogens. The observed accumulation of respective transcripts and enzymatic activities of both chitinase and β-1,3, glucanase were remarkably higher in pathogen-induced cultures. The reduction of disease severity by 70% was observed in pot cultures of banana plantlets infected previously with F. oxysporum after 9 weeks of treatment with T. asperellum. Our findings demonstrate that T. asperellum as originated from banana wilt-contaminated plantations express anti-pathogenic effects based on various modes of action, including competitiveness, antibiosis, and mycoparasitism and might be potentially used as a biological control agent to cope with diseases caused by a broad spectrum of pathogenic fungi of Fusarium genus.