Bioactivity of volatile organic compounds by Aureobasidium species against gray mold of tomato and table grape

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.

Volatile Organic Compounds (VOCs) Produced by Gluconobacter cerinus and Hanseniaspora osmophila Displaying Control Effect against Table Grape-Rot Pathogens

“…For example, our study is supported by past results on Hanseniaspora uvarum, which was shown to be an effective BCA in, e.g., controlling fungal rot in strawberries by biofumigation using VOCs [64]. It reduces the natural development of decay in grapes and strawberries and maintains quality parameters [28,57,65,66]. It also exerts biocontrol against chili fruit rot [67] and green mold of postharvest oranges [68]; and inhibits the growth of B. cinerea with multiple modes of action, including competition for nutrients and space, host defense induction, morphology change and secondary metabolites [57,65,66,69,70].…”

“…Additionally, 2-phenylethanol isolated from K. apiculata showed inhibitory activity against green and blue mold in citrus fruits caused by P. digitatum and P. italicum [19]. It was also shown to play a critical role in the antagonistic activity of A. pullulans against postharvest fruit pathogens both in vitro and in vivo [56,57].…”

“…It reduces the natural development of decay in grapes and strawberries and maintains quality parameters [28,57,65,66]. It also exerts biocontrol against chili fruit rot [67] and green mold of postharvest oranges [68]; and inhibits the growth of B. cinerea with multiple modes of action, including competition for nutrients and space, host defense induction, morphology change and secondary metabolites [57,65,66,69,70]. Indeed, Moreira et al, [71] identified different VOCs produced by Hanseniaspora yeasts during red wine vinifications such as 3-methyl-1-butanol, ethyl acetate, phenylethyl alcohol, butanoic acid, and ethyl ester, similar to results from this study.…”

Culturable Yeasts as Biofertilizers and Biopesticides for a Sustainable Agriculture: A Comprehensive Review

“…They could be considered as ideal antimicrobials since no physical interaction between the biocontrol agent and the food or pathogen is necessary. Antagonistic yeasts of the genus Hanseniaspora [ 112 ] and A. pullulans [ 113 ] showed inhibition efficacy against B. cinerea by producing VOCs. Similarly, killer toxins can also control post-harvest pathogens [ 35 ].…”

Genome, transcriptome and secretome analyses of the antagonistic, yeast-like fungus Aureobasidium pullulans to identify potential biocontrol genes

“…The species A. pullulans is also known as an effective biocontrol agent that is thought to employ a range of mechanisms to suppress the growth of other microorganisms [9]. These mechanisms include direct competition [15][16][17], the secretion of enzymes and secondary metabolites [4-8, 18, 19], the production of volatile compounds [20][21][22][23][24][25], as well as the induction of resistance in crop plants [26,27]. Many Aureobasidium isolates show strong biocontrol activity against destructive plant diseases such as moulds, rots and blights [28][29][30][31][32][33][34][35].…”