Antifungal Activity of Shirazi Thyme (Zataria multiflora Boiss.) Essential Oil against Hypomyces perniciosus, a causal agent of wet bubble disease of Agaricus bisporus

Abstract

Wet bubble disease (WBD) caused by Hypomyces perniciosus is a major constraint of button mushroom (Agaricus bisporus) cultivated worldwide. A few synthetic chemical fungicides are used to control WBD. In our study, the potential of essential oil (EO) from Zataria multiflora in inhibition of H. perniciosus was evaluated as an alternative to chemical fungicides. An isolate of H. perniciosus was isolated from wet bubble diseased A. bisporus and pathogenicity of the mycoparasite was determined under artificially inoculated conditions. The mycoparasitic fungus was identified using sequences of the internal transcribed spacer (ITS) region of ribosomal DNA. The EO was extracted from the aerial parts of Z. multiflora by microwave extraction method and evaluated in vitro for its antifungal activity against H. perniciosus. The EO of Z. multiflora (ZEO) at the tested concentrations (50% and 100%) inhibited the growth of H. perniciosus in the agar diffusion test. The minimum inhibitory concentration (MIC) of ZEO was 0.04% as assessed by the poisoned food technique. The chemical composition of ZEO was determined by gas chromatography-mass spectrometry analysis. A total of 23 compounds were identified. Among them, the most abundant compounds were Linalool (20.3%) and Bornyl acetate (15.5%). Linalool at the tested concentrations of 0.25% and 0.125% completely inhibited the mycelial growth of H. perniciosus in an in vitro assay. These results suggest that ZEO can be exploited for control of WBD.