Abstract
Aureobasidium strains isolated from diverse unconventional environments belonging to the species A. pullulans, A. melanogenum, and A. subglaciale were evaluated for Volatile Organic Compounds (VOCs) production as a part of their modes of action against Botrytis cinerea of tomato and table grape. By in vitro assay, VOCs generated by the antagonists belonging to the species A. subglaciale showed the highest inhibition percentage of the pathogen mycelial growth (65.4%). In vivo tests were conducted with tomatoes and grapes artificially inoculated with B. cinerea conidial suspension, and exposed to VOCs emitted by the most efficient antagonists of each species (AP1, AM10, AS14) showing that VOCs of AP1 (A. pullulans) reduced the incidence by 67%, partially confirmed by the in vitro results. Conversely, on table grape, VOCs produced by all the strains did not control the fungal incidence but were only reducing the infection severity (< 44.4% by A. pullulans; < 30.5% by A. melanogenum, and A. subglaciale). Solid-phase microextraction (SPME) and subsequent gas chromatography coupled to mass spectrometry identified ethanol, 3-methyl-1-butanol, 2-methyl-1-propanol as the most produced VOCs. However, there were differences in the amounts of produced VOCs as well as in their repertoire. The EC50 values of VOCs for reduction of mycelial growth of B. cinerea uncovered 3-methyl-1-butanol as the most effective compound. The study demonstrated that the production and the efficacy of VOCs by Aureobasidium could be directly related to the specific species and pathosystem and uncovers new possibilities for searching more efficient VOCs producing strains in unconventional habitats other than plants.
Highlights
Aureobasidium pullulans is a highly adaptable polymorphic species characterized by great phenotypic plasticity and ubiquitous ecology
Strains were maintained on nutrient yeast dextrose agar (NYDA: 8 g L−1 of nutrient broth, 5 g L−1 of yeast extract, 10 g L−1 of dextrose and 15 g L−1 of technical agar, Oxoid, Basingstoke, UK) and stored at 4 °C until use
The A. pullulans strain AP1 displayed a higher activity of target Volatile Organic Compounds (VOCs) production with respect to A. melanogenum AM10 and A. subglaciale AS14 strains (Fig. 1) mainly for ethanol and 3-methyl-1-butanol
Summary
Aureobasidium pullulans (de Bary) is a highly adaptable polymorphic species characterized by great phenotypic plasticity and ubiquitous ecology. The species complex comprised four varieties until the large genomic differences and substantial physiological differences prompted the separation into four separate species: A. pullulans, A. melanogenum, A. subglaciale, and A. namibiae. These species display different patterns of melanisation, different temperature growth limits and salt tolerance (Gostinčar et al 2014), various biofilm forming capacity and differences in repertoire of enzymatic activities (Zajc et al 2019; Zajc et al 2020). The species A. pullulans is recognized as one of the most promising biocontrol agents used in plant protection, in particular against postharvest diseases (Di Francesco et al 2018; Di Francesco et al 2020a; Zhang et al 2010), while A. subglaciale is the least studied species in the field of crop defense, without any recognized biocontrol potential
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
