Abstract
Abstract Antibiosis is the mechanism by which certain microorganisms respond to the presence of others, secreting compounds or metabolites capable of inhibiting or impeding their development. The crude extract of Trichoderma contains a mixture of secondary compounds, which may show antibiotic effect, and has been used for the prospect of this fungus for biological control and other industrial purposes. Faced with the increasing demand of agriculture for ecologically compatible alternatives for the management of diseases, this work aimed to investigate the spectrum of action of Non-Volatile Metabolites (NVMs) of Trichoderma isolates against different plant pathogenic fungi. The antagonistic potential of NVMs was evaluated through the incorporation method of the filtered liquid extract in PDA medium. The assays showed that all the NVMs produced inhibited the fungus Sclerotinia sclerotiorum similarly. On the other hand, strains CEN1245 and CEN1274, both belonging to the species Trichoderma brevicompactum, showed broad spectrum against Sclerotium rolfsii, Colletotrichum gloesporioides, Verticillium dahliae, Fusarium oxysporum and Cylindrocladium sp. The present study describes isolates producing non-volatile metabolites with broad spectrum of antifungal action, as well as pathogen-specific. The Trichoderma spp. NVMs obtained from different soil samples cultivated with vegetables, cassava and maize were efficient in inhibiting plant pathogenic fungi belonging to other patossystems, such as forest or fruit, which could increase their potential application in biological control of plant diseases. In addition, these antagonistic fungi should be studied in greater depth for the identification of bioactive molecules of industrial interest or in commercial formulations of products for biological control of plant pathogens.
Highlights
Trichoderma Persoon is a hyperparasite fungus that uses different mechanisms of biological control, which include: parasitism, antibiosis, competition, induction of resistance and growth promotion (Kumar 2013)
Since all isolates produced active Non-Volatile Metabolites (NVMs) against S. sclerotiorum, the results were compared with those obtained in previously performed dual culture tests (Marques et al 2016), and a greater inhibition was observed with the use of the culture filtrates than in the direct comparison between pathogen and antagonist
It was observed that the three different species, T. harzianum, T. spirale and T. brevicompactum were effective against the fungus that causes white mold (Figure 1)
Summary
Trichoderma Persoon is a hyperparasite fungus that uses different mechanisms of biological control, which include: parasitism, antibiosis, competition, induction of resistance and growth promotion (Kumar 2013). According to Dennis & Webster (1971a, b), antibiotic compounds may be Volatile Metabolites (VMs) and Non-Volatile Metabolites (NVMs). These molecules are not essential, in some cases they are important for the selective survival of organisms under certain conditions (Donidio & Monciardini 2002), eliminating microbial competition and, leading to greater availability of scarce food sources in the soil (Benítez et al 2004). Secondary metabolites (SMs) are produced during the stationary phase and in lesser quantities than the primary ones, encompassing a diversified class of low molecular weight substances and produced by specific groups of organisms (Hanson 2003), which include antibiotics
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