Growth Inhibition of Phytopathogenic Fungi and Oomycetes by Basidiomycete Irpex lacteus and Identification of its Antimicrobial Extracellular Metabolites

Abstract

In dual culture confrontation assays, basidiomycete Irpex lacteus efficiently antagonized Fusarium spp., Colletotrichum spp., and Phytophthora spp. phytopathogenic strains, with growth inhibition percentages between 16.7-46.3%. Antibiosis assays evaluating the inhibitory effect of soluble extracellular metabolites indicated I. lacteus strain inhibited phytopathogens growth between 32.0-86.7%. Metabolites in the extracellular broth filtrate, identified by UPLC-QTOF mass spectrometer, included nine terpenes, two aldehydes, and derivatives of a polyketide, a quinazoline, and a xanthone, several of which had antifungal activity. I. lacteus strain and its extracellular metabolites might be valuable tools for phytopathogenic fungi and oomycete biocontrol of agricultural relevance.

Keywords: antagonism; antifungal; extracellular metabolites; mycelium; terpenes.

Fig 1.

Phytopathogens growth inhibition in dual culture antagonism and antibiosis assays by I. lacteus (CMU-8413). In dual culture antagonism assays, I. lacteus was inoculated at the left. Tested phytopathogens were Fusarium pseudocircinatum, Fusarium mexicanum, Colletotrichum coccodes, Colletotrichum gloeosporioides, Phytophthora capsici, and Phytophthora cinnamomi. Assays were conducted in potato dextrose agar (PDA) medium at 28°C. Growth inhibition percentages are the mean of three independent assays and standard deviation (S.D.) is shown in parenthesis. Statistically significant (p < 0.01) growth inhibition values when compared with their respective control are indicated with an asterisk. Significance was determined by Student’s t-tests, independent by groups, and they were carried out using STATISTICA data analysis software system (StatSoft, Inc. 2007, version 7. http://www.statsoft.com).