Biocontrol activities of gray mold of grapes with the volatile organic compounds generated by yeast HXMG-1 isolated from grapes

The pathogenic bacterias of postharvest crops are reduced by volatile organic compounds (VOCs) generated by yeasts. The yeast HXMG-1, which works well against gray mold of grapes pathogens (Botrytis cinerea), was assessed for its potential to create volatile organic compounds (VOCs) as one of its ways of working. Using a double Petri dish assay, the effect of HXGM-1-produced VOCs on mycelial development and spore development of the target pathogens was evaluated. Compared to the control, the VOCs produced by yeast HXMG-1 significantly restricted the growth of mycelium and spore germination of Botrytis cinerea. Specifically, the mycelium growth of Botrytis cinerea was entirely restricted and the rate of spore germination of Botrytis cinerea only 20.11% at a concentration of 1×10⁹ CFU/mL. It was also found that the VOCs could significantly inhibit mycelium growth with 82.46% inhibition with treatment of concentration of 1×10⁸ CFU/mL. The VOCs caused the mycelium to grow curved, resulting in larger mycelial tips, fewer nuclei, and shorter mycelial septum spacing. In in vivo tests, noninjure or injure grapes were artificially inoculated with pathogen hyphal disk followed by bio-fumigation with VOCs generated by yeast HXMG-1, and the treatments (Wp2 and Wp3) significantly controlled pathogenic infection, confirming the results of in vitro tests. Through the creation of a phylogenetic tree, HXMG-1 was recognized as a member of the Ascomycota, Hemiascomycota, Yeasts, and Hansenula sp. families. In conclusion, the yeast strain HXMG-1 created VOCs that significantly inhibited the development of Botrytis cinerea on grapes and is expected to be further developed and utilized. This study lays the foundation for the using of Hansenula sp. for biological control of postharvest diseases.