Antifungal properties of volatile organic compounds produced by Daldinia eschscholtzii MFLUCC 19-0493 isolated from Barleria prionitis leaves against Colletotrichum acutatum and its postharvest infections on strawberry fruits

• Type of Material: Article
• Authors: Sarunpron Khruengsai, Mae Fah Luang University; Patcharee Pripdeevech, Mae Fah Luang University; Chutima Tanapichatsakul, Mae Fah Luang University; Chanin Srisuwannapa, Mae Fah Luang University; Priya E D’Souza, Rollins School of Public Health; Parinya Panuwet, Emory University
• Language: English
• Date: 2021-04-16
• Publisher: PeerJ, Inc.
• Publication Version: Final Published Version
• Copyright Statement: ©2021 Khruengsai et al.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.7717/peerj.11242
• Title of Journal or Parent Work: PeerJ
• Volume: 9
• Grant/Funding Information: This work was financially supported by the Mae Fah Luang University grant and the Royal Golden Jubilee Ph.D. Programme through the grant no. PHD/0193/2560. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
• Keywords: Colletotrichum acutatum; Fungal endophyte; Strawberry; Anthracnose; Biocontrol; Barleria prionitis
• Research Categories: Health Sciences, Public Health; Environmental Sciences

Abstract

Fungal endophytes are microorganisms living symbiotically with a host plant. They can produce volatile organic compounds (VOCs) that have antimicrobial activity. This study aimed to isolate endophytic fungi from Barleria prionitis plants grown in Thailand and to investigate the antifungal properties of their VOCs against Colletotrichum acutatum, a causal agent of anthracnose disease on post-harvest strawberry fruits. A total of 34 endophytic fungi were isolated from leaves of B. prionitis. The VOCs produced from each individual isolate were screened for their antifungal activity against C. acutatum using a dual-culture plate method. From this in vitro screening experiment, the VOCs produced by the endophytic isolate BP11 were found to have the highest inhibition percentage (80.3%) against the mycelial growth of C. acutatum. The endophytic isolate BP11 was molecularly identified as Daldinia eschscholtzii MFLUCC 19-0493. This strain was then selected for an in vivo experiment. Results from the in vivo experiment indicated that the VOCs produced by D. eschscholtzii MFLUCC 19-0493 were able to inhibit infections by C. acutatum on organic fresh strawberry fruits with an average inhibition percentage of 72.4%. The quality of the pathogen-inoculated strawberry fruits treated with VOCs produced by D. eschscholtzii MFLUCC 19-0493 was evaluated. Their fruit firmness, total soluble solids, and pH were found to be similar to the untreated strawberry fruits. Solid phase microextraction-gas chromatographic-mass spectrometric analysis of the VOCs produced by D. eschscholtzii MFLUCC 19-0493 led to the detection and identification of 60 compounds. The major compounds were elemicin (23.8%), benzaldehyde dimethyl acetal (8.5%), ethyl sorbate (6.8%), methyl geranate (6.5%), trans-sabinene hydrate (5.4%), and 3,5-dimethyl-4-heptanone (5.1%). Each major compound was tested for its antifungal activity against C. acutatum using the in vitro assay. While all these selected VOCs showed varying degrees of antifungal activity, elemicin was found to possess the strongest antifungal activity. This work suggests that D. eschscholtzii MFLUCC 19-0493 could be a promising natural preservative for controlling C. acutatum associated anthracnose disease in strawberry fruits during the post-harvest period.